2017masthead v12n5

IJSPT

INTERNATIONAL JOURNAL OF SPORTS PHYSICAL THERAPY

VOLUME TWELVE issue FIVE OCTOBER 2017

IJSPT

INTERNATIONAL JOURNAL OF SPORTS PHYSICAL THERAPY

Editor in Chief Michael L. Voight, PT, DHSc, OCS, SCS, ATC, CSCS Belmont University Nashville, Tennessee – USA

Associate Editors: John Dewitt PT, DPT, SCS, ATC The Ohio State University Sports Medicine Columbus, Ohio - USA

Senior Associate Editor Barbara Hoogenboom, PT, EdD, SCS, ATC Grand Valley State University Grand Rapids, Michigan - USA

Terry Grindstaff PhD, PT, ATC Creighton University Omaha, Nebraska - USA

Manuscript Coordinator Ashley Campbell, PT, DPT, SCS, ATC Associate Editor, Thematic Issues: Robert Manske, PT, DPT, Med, SCS, ATC, CSCS Wichita State University Wichita, Kansas – USA

International Associate Editors: Mario Bizzini, PT, MSc Schulthess Clinic Zürich – Switzerland Henning Langberg, PT, PhD, MSc Institute of Sports Medicine Copenhagen – Denmark

Editorial Board: Scott Anderson, PT, Dip Sport PT Northgate Physical Therapy Regina, Saskatchewan – Canada

Mark S. De Carlo, PT, DPT, MHA, SCS, ATC Accelerated Rehabilitation Indianapolis, Indiana – USA

Lindsay Becker, PT, DPT, SCS, CSCS The Ohio State University Sportsmedicine Center Columbus, Ohio – USA

Todd S. Ellenbecker, DPT, SCS, OCS Physiotherapy Associates Scottsdale Sports Clinic Scottsdale, Arizona – USA

Barton Bishop, PT, DPT, SCS, CSCS Sport and Spine Rehab of Rockville Rockville, Maryland – USA

John A. Guido, Jr., PT, MHS, SCS, ATC, CSCS Ochsner Health Systems New Orleans, Louisiana – USA

Turner A. “TAB” Blackburn, Jr., MEd, PT, ATC Clemson Sports Medicine and Rehabilitation Manchester, Georgia – USA

Elizabeth L. Harrison, PT, PhD, Dip Sport PT University of Saskatchewan Saskatoon, Saskatchewan – Canada

Lori A Bolgla, PT, PhD, MAcc, ATC Augusta University Augusta, Georgia – USA

Walter L. Jenkins, PT, DHS, ATC East Carolina University Greenville, North Carolina - USA

Robert J. Butler, PT, DPT, PhD Duke University Durham, NC – USA

Daniel S. Lorenz, PT, DPT, ATC, CSCS Providence Medical Center Kansas City, Kansas - USA

Duane Button, PhD, CSEP-CEP Memorial University St. John’s, Newfoundland and Labrador – Canada

Terry Malone, PT, EdD, ATC, FAPTA University of Kentucky Lexington, Kentucky – USA

Rick Clark, PT, DScPT, CCCE Air Force Academy Colorado Springs, CO – USA

Peter J. McNair, PT, PhD Auckland University of Technology Auckland – New Zealand

George J. Davies, PT, DPT, SCS, ATC, FAPTA Armstrong Atlantic State University Savannah, Georgia – USA

EDITORIAL STAFF & BOARD

Phil Page, PT, PhD, ATC, CSCS The Hygenic Corporation Akron, Ohio – USA

Timothy Uhl, PT, PhD, ATC University of Kentucky Lexington, Kentucky – USA

Mark Paterno, PT, PhD, MBA, SCS, ATC Cincinnati Children’s Hospital Medical Center Cincinnati, Ohio – USA

Mark D. Weber, PT, PhD, SCS, ATC University of Mississippi Medical Center Jackson, Mississippi – USA

Charles E. Rainey, PT, DSc, DPT, MS, OCS, SCS, CSCS, FAAOMPT United States Public Health Service Springfield, Missouri - USA

Kevin Wilk, PT, DPT Champion Sports Medicine Birmingham, Alabama – USA

Michael P. Reiman, PT, DPT, OCS, SCS, ATC, FAAOMPT, CSCS Duke University School of Medicine Durham, North Carolina – USA Mark F. Reinking, PT, PhD, SCS, ATC Saint Louis University St. Louis, Missouri – USA Jill Robertson, PT, MSc (PT), Dip Manip PT Beaverbank Orthopaedic and Sport Physiotherapy Halifax, Nova Scotia – Canada Kevin Robinson, PT, DSc, OCS Belmont University Nashville, Tennessee – USA Barbara Sanders, PT, PhD, SCS, FAPTA Texas State University-San Marcos San Marcos, Texas – USA Teresa L. Schuemann, PT, DPT, SCS, ATC, CSCS Colorado Physical Therapy Specialists Fort Collins, Colorado – USA Brandon Schmitt, PT, DPT, ATC PRO Sports Physical Therapy of Westchester Scarsdale, New York - USA Patrick Sells, DA, ES Belmont University Nashville, Tennessee – USA Laurie Stickler, MSPT, OCS Grand Valley State University Grand Rapids, Michigan – USA Steven R. Tippett, PT, PhD, SCS, ATC Bradley University Peoria, Illinois – USA Timothy F. Tyler, PT, ATC NISMAT Lenox Hill Hospital New York, New York – USA

Erik Witvrouw, PT, PhD Ghent University Ghent – Belgium

international JOURNAL OF

IJSPT

SPORTS PHYSICAL THERAPY

I N T E R N AT I O N A L J O U R N A L OF SPORTS PHYSICAL THERAPY

SPORTS PHYSICAL THERAPY SECTION

Editorial Staff

Executive Committee

Michael L. Voight, PT, DHSc, OCS, SCS, ATC Editor-in-Chief

Walter L. Jenkins, PT, DHS, LATC, ATC President

Barbara Hoogenboom, PT, EdD, SCS, ATC Grand Valley State University Grand Rapids, Michigan - USA Senior Associate Editor

Blaise Williams, PT, PhD Vice President Mitchell Rauh, PT, PhD, MPH, FACSM Secretary

Robert Manske, PT, DPT, Med, SCS, ATC, CSCS Wichita State University Wichita, Kansas – USA Associate Editor, Thematic Issues

Bryan Heiderscheit, PT, PhD Treasurer Stacey J. Pagorek, PT, DPT, SCS, ATC Representative-At-Large

Associate Editors John Dewitt PT, DPT, SCS, ATC The Ohio State University Sports Medicine Columbus, Ohio - USA

Administration Mark S. De Carlo, PT, DPT, MHA, SCS, ATC Executive Director

Terry Grindstaff PhD, PT, ATC Creighton University Omaha, Nebraska - USA

Mary Wilkinson Director of Marketing/Webmaster Managing Editor, Publications

International Associate Editors Mario Bizzini, PT, MSc Schulthess Clinic Zürich – Switzerland

Contact Information P.O. Box 431 Zionsville, Indiana 46077 877.732.5009 Toll Free 317.669.8276 Fax www.spts.org

Henning Langberg, PT, PhD, MSc Institute of Sports Medicine Copenhagen – Denmark Ashley Campbell Manuscript Coordinator Mary Wilkinson Managing Editor

Advertising Sales The International Journal of Sports Physical Therapy accepts advertising. Email Mary Wilkinson, Marketing Director, at mwilkinson@spts.org or contact by phone at 317.501.0805.

IJSPT is a bimonthly publication, with release dates in February, April, June, August, October and December.

I N T E R N AT I O N A L J O U R N A L OF SPORTS PHYSICAL THERAPY is a publication of the Sports Physical Therapy Section of the American Physical Therapy Association. IJSPT is also an official journal of the International Federation of Sports Physical Therapy (IFSPT).

ISSN 2159-2896

T

IFSPT

TABLE OF CONTENTS VOLUME 12, NUMBER 5 NEW to this issue is the addition of a DOI for each manuscript. A DOI is a “Digital Object Identifier” that is a unique alphanumeric code assigned to each paper or publication. Journal publishers assign DOI’s to electronic copies of individual articles to ensure that they easily located by readers around the world. Page Number

Article Title

ORIGINAL RESEARCH 711 The Effect of Heel Lifts on Patellofemoral Joint Stress During Running. Authors: Mestelle Z, Kernozek T, Adkins KS, Miller J, Gheidi N 718

Comparison of Hamstring Muscle Activation During High-Speed Running and Various Hamstring Strengthening Exercises. Authors: van den Tillar R, Solheim JAB, Bencke J

728

The Efficacy of Angle-Matched Isokinetic Knee Flexor and Extensor Strength Parameters in Predicting Agility Test Performance Authors: Greig M, Naylor J

737

Lower Extremity Kinematics of ACL-Repaired and Non-Injured Females when using Knee Savers®. Authors: Stone WJ, Arnett SW, Hoover DL

747

Comparison of Dry Needling vs. Sham on the Performance of Vertical Jump. Authors: Bandy WD, Nelson R, Beamer L

752

Inter-Rater Reliability of the Selective Functional Movement Assessment (SFMA) by SFMA Certified Physical Therapists with Similar Clinical and Rating Experience. Authors: Dolbeer J, Mason J, Morris J, Crowell M, Goss D

764

Hip Range of Motion in Recreational Weight Training Participants: A Descriptive Report. Authors: Cheatham S, Hanney WJ, Kolber MJ

774

Development of a Screening Protocol to Identify Individuals With Dysfunctional Breathing. Authors: Kiesel K, Rhodes T, Mueller J, Waninger A, Butler R

787

Sports Physical Therapy Curricula in Physical Therapist Professional Degree Programs. Authors: Mulligan EP, DeVahl J

798

Shoulder Pain in Competitive Teenage Swimmers and its Prevention: A Retrospective Epidemiological Cross Sectional Study of Prevalence. Authors: Tessaro M, Granzotto G, Poser A, Plebani G, Rossi A

812

Age Differences in Measures of Functional Movement and Performance in Highly Trained Youth Basketball Players. Authors: Gonzalo-Skok O, Serna J, Rhea MR, Marin PJ

822

Injury Patterns in Adolescent Elite Endurance Athletes Participating in Running, Orienteering, and Cross-Country Skiing. Authors: von Rosen P, Flostrom F, Frohm A, Heijne A

833

Injuries in Quidditch: A Descriptive Epidemiological Study. Authors: Pennington R, Cooper A, Edmond E, Faulkner A, Reidy MJ

CASE STUDIES 840

848

Functional Outcomes of Hip Arthroscopy in an Active Duty Military Population Utilizing a Criterion-Based Early Weight Bearing Progression – A Case Series. Authors: Shaw KA, Jacobs JM, Evanson JR, Pniewski J, Mueller T, Bojescul JA Exercise, Manual Therapy and Postural Re-education for Uncontrolled Ear Twitching and Related Impairments after Whiplash Injury: A Case Report. Authors: Flanders K, Feldner H

IJSPT

ORIGINAL RESEARCH

EFFECT OF HEEL LIFTS ON PATELLOFEMORAL JOINT STRESS DURING RUNNING Zachary Mestelle, DPT1 Thomas Kernozek, PhD, FACSM1 Kelly S. Adkins, DPT1 Jessica Miller, DPT1 Naghmeh Gheidi, PhD2

ABSTRACT Background: Patellofemoral pain is a debilitating injury for many recreational runners. Excessive patellofemoral joint stress may be the underlying source of pain and interventions often focus on ways to reduce patellofemoral joint stress. Purpose: Heel lifts have been used as an intervention within Achilles tendon rehabilitation programs and to address leg length discrepancies. The purpose of this study was to examine the effect of running with heel lifts on patellofemoral joint stress, patellofemoral stress impulse, quadriceps force, step length, cadence, and other related kinematic and spatiotemporal variables. Study Design: A repeated-measures research design Methods: Sixteen healthy female runners completed five running trials in a controlled laboratory setting with and without 11mm heel lifts inserted in a standard running shoe. Kinetic and kinematic data were used in combination with a static optimization technique to estimate individual muscle forces. These data were inserted into a patellofemoral joint model which was used to estimate patellofemoral joint stress and other variables during running. Results: When running with heel lifts, peak patellofemoral joint stress and patellofemoral stress impulse were reduced by a 4.2% (p=0.049) and 9.3% (p=0.002). Initial center of pressure was shifted anteriorly 9.1% when running with heel lifts (p<0.001) despite all runners utilizing a heel strike pattern. Dorsiflexion at initial contact was reduced 28% (p=0.016) when heel lifts were donned. No differences in step length and cadence (p>0.05) were shown between conditions. Conclusions: Heel lift use resulted in decreased patellofemoral joint stress and impulse without associated changes in step length or frequency, or other variables shown to influence patellofemoral joint stress. The center of pressure at initial contact was also more anterior using heel lifts. The use of heel lifts may have therapeutic benefits for runners with patellofemoral pain if the primary goal is to reduce patellofemoral joint stress. Level of Evidence: 3b Key words: Heel lifts, knee, patellofemoral joint stress, rehabilitation, running

1

La Crosse Institute for Movement Science, Department of Health Professions – Physical Therapy Program, University of Wisconsin-La Crosse, La Crosse, WI, USA; 2 Department of Exercise and Sport Science, University of Wisconsin-La Crosse, La Crosse, WI, USA

CORRESPONDING AUTHOR Thomas W. Kernozek, PhD, FACSM University of Wisconsin-La Crosse Department of Health Professions Health Science Center 1300 Badger Street La Crosse, WI, USA Tel: (608) 785-8468 Fax: (608) 785-8460 E-mail: tkernozek@uwlax.edu

The International Journal of Sports Physical Therapy | Volume 12, Number 5 | October 2017 | Page 711 DOI: 10.16603/ijspt20170711

INTRODUCTION Running is a common form of aerobic exercise. However, runners are at risk for developing a variety of lower extremity overuse injuries such as patellofemoral pain (PFP). Patellofemoral joint pain is frequently described as anterior knee pain with an insidious onset, usually exacerbated during exercise involving running or deep knee flexion, often becoming persistent if not appropriately addressed.1,2 Patellofemoral pain is frequently seen in outpatient orthopedic clinics, with 17% of kneerelated and 7.3% all orthopedic visits resulting in the diagnosis of patellofemoral pain disorder. 3,4 In addition, female runners are at greater risk, with incidence rates being two to three times higher than males.1 Patellofemoral pain etiology is believed to be multifactorial where poor patellar alignment, patellar maltracking due to muscular imbalance, decreased vastus medialis oblique muscle mass, weak hip musculature, training errors, and a rearfoot strike pattern have been implicated in development of this condition.1,5-7 The underlying effects of such factors may result in aberrant patellofemoral joint stresses (PFJS) which are thought to damage the patella and femoral subchondral tissues.2,8-10 Musculoskeletal modeling studies have investigated PFJS during various movements to characterize this loading.11-14 Patellofemoral (PF) joint stress is determined by dividing the PF joint reaction force by the PF contact area. Knee flexion angle influences PF joint contact area2,15 while the interaction of quadriceps force and knee flexion influence the magnitude of PF joint reaction force.16,17 Conservative intervention strategies of PFP often involve attempts to alter running mechanics.12,13,16 Decreasing step length by 10% results in a 15-20% decrease in patellofemoral joint (PFJ) kinetics,16 while increasing the runner’s cadence by 10% was successful in reducing PFJ forces by 14%.12 Teng and Powers reported that a 7 degree increase in trunk flexion led to significant decreases in knee extensor energy absorption and generation.13 Another strategy utilized to alter PFJS is adopting a forefoot strike (FFS) pattern during running. A forefoot strike pattern occurs when a runner contacts the ground with the anterior third of their shoe compared to a rearfoot striker (RFS) who contacts the ground with the

posterior third.18 Biomechanical variations that occur between the foot strike patterns may account for the differences in PFJS, as FFS runners initially land with a plantarflexed ankle, flexed knee, and lower vertical loading rates.19-21 Overall, mild-moderate repetitive stress injuries (ie patellofemoral pain syndrome [PFPS], medial tibial stress reaction, IT band syndrome) were 2.5 times higher in RFS runners22 and multiple authors have reported that runners who adopt a FFS pattern experience significant reduction (13-27%) in peak PFJS.12,14,19 One recent case series examined the efficacy of converting runners from a RFS to FFS pattern.23 These patients were able to decrease their PFP and maintain changes in foot strike pattern during follow up session.23 However, adopting a FFS running technique may be difficult, requiring extensive time and specialized equipment. The use of heel lifts has traditionally been used in Achilles tendon rehabilitation or to correct leg length discrepancies.24-26 Insertion of heel lifts into a standard running shoe is both convenient and affordable, however their effects at more proximal joints have yet to be analyzed. Of particular interest is the PJF, which has been shown to be influenced by foot position during running.19-21 The purpose of this study was to examine the effect of running with heel lifts on patellofemoral joint stress, patellofemoral stress impulse, quadriceps force, step length, cadence, and other related kinematic and spatiotemporal variables. Secondary analyses aimed to discern if kinematic or spatiotemporal differences occurred between running in heel lift conditions, most notably: peak knee flexion angle, peak dorsiflexion angle, peak plantarflexion angle, dorsiflexion at initial contact, knee angle at initial contact, step length, stride cadence, and initial center of pressure. The working hypothesis was that heel lifts would decrease peak PFJS, quadriceps force, PF stress impulse, and dorsiflexion at initial contact, as well as increase initial knee flexion angle and shift the initial center of pressure anteriorly but would have no effect on peak plantarflexion angle, step length, or stride cadence. METHODS Subjects Sixteen healthy active females (Age: 21.7 ± 1.6 yrs; height: 169.8 ± 5.8 cm; mass: 61.3 ± 9.6kg) were

The International Journal of Sports Physical Therapy | Volume 12, Number 5 | October 2017 | Page 712

recruited from October 2015 to December 2015. Sample size was based off previous repeated measure studies that focused on PF kinetics and kinematics.12-14,19 All participants included were rearfoot strikers, as determined by center of pressure at initial contact occurring in the rear most third of the foot during testing.18 Additional inclusion criteria included five years of recreational running experience, self-reported running routine of >10 miles per week, and a score of at least level five on the Tegner Activity Level Scale (a questionnaire of regular participation with recreational sports which require running). Exclusion criteria consisted of current lower extremity injury or pain, or surgery within the last year. Informed consent to the testing protocol was obtained from all subjects prior to participation; all methods were approved by the University of Wisconsin-La Crosse Institutional Review Board. Protocol Prior to the running trials, participants were fitted with the same model of footwear (Model 625SB, New Balance, Boston, MA), reflective markers, and tightfitting clothing. All participants completed a fiveminute treadmill warm-up walking at a self-selected speed. After several practice trials, participants ran five successful trials down a 20-m runway under two randomized conditions: 1) No heel lift and 2) With 11mm heel lift. A trial was deemed successful when the participant demonstrated a rearfoot strike pattern, proper speed, and was observed to not target the force plate. A predetermined speed of 3.46 m/s ± 2.5% was selected and monitored via two photoelectric timers placed 2.3 m apart. Instrumentation Forty-seven reflective markers were placed at predetermined anatomical landmarks using a modified Helen Hayes type marker set for three-dimensional (3D) data collection.14 A static, neutral standing calibration was collected prior to both conditions. The calcaneal reflective markers were raised 11mm during heel lift conditions, to correspond with the associated raising of the heel within the shoe. Kinematic data were recorded at 180 Hz with 15 motion analysis cameras (Motion Analysis Corporation, Santa Rosa, CA, USA) surrounding the runway. Kinetic data were simultaneously collected using a force

platform flush with the runway, synchronized with the cameras, and sampled at 1800 Hz (Model 4080, Bertec Corporation, Columbus, OH, USA). Data Processing Using the Human Body Model (Motek ForceLink, Amsterdam, the Netherlands), muscle forces were calculated using a musculoskeletal model with 16 rigid segments, 44 degrees of freedom (DOF), and 300 muscle tendon units.27 Estimates of muscle force were based on joint moments by minimizing a static cost function at each time step where the sum of the squared muscle activation was related to the maximum muscle strengths.28,29 Muscle forces of the rectus femoris, vastus medialis, vastus lateralis, and vastus intermedius were summed to determine total quadriceps force. To determine PFJ reaction force, the following equation derived by Brechter and Powers8 was used to calculate the k constant: k(x) = (4.62e-01 + 1.47e-03x – 3.84e-05x2) / (1 – 1.62 e-02x + 1.55 e-04x2 – 6.98 e-02x3) where x is the knee joint angle in the sagittal plane. The constant k signifies the amount of the quadriceps force that is directly imposed on the PF joint from the knee joint angle and quadriceps muscle orientation as described by van Eijden et al.30 Therefore, PF joint reaction force(x) = k(x) × quadriceps force(x) Data from Connolly et al15 were used to determine PF joint contact area as a function of knee angle: PF contact area(x) = 0.0781x2 + 0.6763x + 151.75 PF joint stress was calculated by dividing PF joint reaction force by the contact area: PF joint stress(x) = PF joint reaction force(x) / PF contact area(x) Average of each of the kinematic and kinetic parameters were examined during from five performance trials for each condition during the stance phase of the running cycle. This was determined when using a 10 N threshold from force platform measurements. Statistical Analysis Multivariate analysis of variance (MANOVA) statistics with repeated measures were performed to com-

The International Journal of Sports Physical Therapy | Volume 12, Number 5 | October 2017 | Page 713

pare within subject differences between heel lift and no lift conditions. All statistics were calculated using SPSS Version 23 (IBM, Armonk, NY) with an a-priori significance of p<0.05. Cohen’s d was calculated to determine effect size for each dependent measure. RESULTS All subjects landed with a RFS pattern with an initial center of pressure location of 31.21% ± 11.10% of foot length during heel lift trials and 22.13% ± 8.55% with the no heel lift inserted, which indicated a 9.1% anterior shift when running with heel lifts (p<0.001). During heel lift trials, a 4.2% (p=0.049) and 9.3% (p=0.002) decrease was observed in peak PFJS and PF stress impulse, respectively (Table 1). Figures 1 and 2 depict these reductions in both PFJS and PF stress impulse throughout the stance phase during heel lift trials. Peak quadriceps force decreased 3.8% when heel lifts were inserted, however this was not significant (p=0.053). When donning the heel lift, peak ankle dorsiflexion was reduced 20% (p=0.006), while ankle dorsiflexion at initial contact was reduced 28% (p=0.016). No differences were found for key spatiotemporal data such as step length and cadence and other kinematic variables, such as peak ankle

plantarflexion, peak knee flexion and knee flexion at initial contact (p>0.05). DISCUSSION The primary purpose was to compare the effects of heel lifts on peak PFJS, PF stress impulse, and quadriceps force during running. The study findings partially support the hypotheses that heel lift use would decrease peak PFJS and PF stress impulse, however no difference in peak quadriceps force was found between conditions. Secondary analyses examining kinematics and spatiotemporal variables also partially supported our hypothesis, as indicated by significant differences in dorsiflexion and center of pressure but not knee flexion at initial contact, step length, or stride cadence. This may be the first study examining how the use of heel lifts influence PFJS in running. The justification for raising the heel of RFS runners is to alter the kinematics and kinetics to more closely resemble a FFS runner, a running pattern that has been shown to decrease PFJS.12,14,19 Overall, the results of heel lift insert trials tended to trend towards FFS kinetics and kinematics, as demonstrated by an anterior shift

Table 1. Means and standard deviations (SD) for peak patellofemoral joint stress (PFJS), patellofemoral (PF) joint stress time integral, peak quadriceps force, initial contact ankle dorsiflexion, peak ankle dorsiflexion, initial contact knee angle, peak knee flexion, initial contact center of pressure location, step length and cadence when running with and without a heel lift.

The International Journal of Sports Physical Therapy | Volume 12, Number 5 | October 2017 | Page 714

PFJS.12,14,19 Running with 11 mm heel lift had a 4.2% decrease in peak PFJS (p=0.049) and small effect size (ES=0.24). This study found a 9.3% decrease (p=0.002, ES=0.54) in PF stress impulse, which factors in both the magnitude and duration the joint is under stress during each step. With an average step length of 0.76 m, each of the participants would have taken approximately 1322 steps over one kilometer. When the per step reductions are summed over a one kilometer distance, the cumulative effect is a 2445 Mpa*s reduction in total PF stress impulse. Similarly, peak quadriceps force trended downward (p=0.053) during heel lift insert trials. This may be related to the center of pressure being more anterior on the foot thus bringing the resultant ground reaction force vector closer to the knee. Figure 1. Ensemble average Patellofemoral joint stress (MPa) during running with heel lift (Run+Lift) and running without heel lift (Run No Lift).

Figure 2. Ensemble average center of pressure during running with heel lift (Run+Lift) and running without heel lift (Run No Lift).

in initial center of pressure, and decreased PFJS, PF stress impulse, and dorsiflexion at initial contact. High PF joint stress and strain have been associated with PFPS2,10 therefore strategies to reduce PFJS appear warranted. Previous studies have reported FFS runners experience a 13-27% reduction in peak

Kinematic comparisons of running with heel lift and a FFS pattern revealed some similarities. Similar to FFS runners, participants running with heel lift inserts contacted the ground with a relative increase in plantarflexion.19,20 The relative 1.8 degree increase in initial plantarflexion during lift conditions is considerably less than the 16.1 degree weighted mean increase reported from the meta-analysis of three studies by Almeida et al. which compared FFS to RFS runners.20 This meta-analysis also depicted a 3.1% increase in knee flexion angle at initial contact in FFS runners.20 This contrasts to our study which depicted no differences between the no lift and lift conditions. Despite the center of pressure being more anterior (31.21% ± 11.10% with lift vs. 22.13% ± 8.55% without lift), subjects were still utilizing a RFS. This may explain similarities in knee flexion angle at initial contact to those previously reported of RFS runners.14,20,21 As hypothesized, step length and cadence were similar between lift conditions, which suggests they did not play a significant role in altering PFJS. This is important to note, as previous studies have found altering these variables can reduce PFJS.12,16 This further strengthens the case that the anterior shift in center of pressure is the primary driving force for decreased PFJS and PF stress impulse observed in our study. Running with a FFS pattern may not be without its drawbacks, placing runners at an increased risk for injuries involving the Achilles tendon, metatarsals, or other plantar structures.31,32 Because of this, it is

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widely accepted that when transitioning from one foot strike pattern to another, a gradual transition is indicated.14,22,32 Implementation of heel lifts may help to serve as an intermediate way to decrease PFJS since it appears to move the center of pressure more anteriorly thereby reducing both PFJS and PF stress impulse during stance phase of running. Perhaps even the use of differing amounts of lift may serve to promote such a transition. Both the practical and cost-effective nature of this intervention may be of benefit. One pair of heel lifts are relatively inexpensive, typically less than $10/ pair. This is in stark contrast to studies that have implemented programs aimed at altering foot strike patterns. These studies have required specialized equipment in addition to large amounts of time and effort from both the participants and clinical researchers.23,33 Furthermore, the heel lifts are simple to utilize in a variety of shoe sizes and styles. Lastly, participants in this study were not given specific instructions to run in a certain manner yet still experienced decreased PFJS and PF stress impulse. One may be able to surmise from this investigation that runners using this intervention will not need any certain coaching or feedback upon implementation as none was provided in this study. Future studies may build from these works in several ways. For starters, monitoring trunk flexion and hip extensor force generation with and without heel lifts may help to determine what influence hip musculature may have at altering PFJS when heel lifts are donned. Analyzing the relationship between heel lift size and/or running speed would also be warranted, as only one lift size and running speed were examined in the current study. Lastly, recruiting runners actively suffering from PFPS may be warranted in determining the efficacy of using heel lifts in reducing patient symptoms. Limitations Results of this study must be analyzed within the context of certain limitations. First, the PF joint model was generalized from previous research and failed to take into account each subjects individual anatomical and musculoskeletal differences. This model was two dimensional in nature and did not account for loading due to joint motion or loading from other

planes. While an improved way to estimate muscle forces, static optimization is still an estimation of muscle force production during dynamic activities. This study contained a relatively small number of subjects and therefore may not be generalizable to a larger sample of females, male subjects or clinical population of runners seeking treatment for patellofemoral pain. Finally, force plate targeting was determined via qualitative visual analysis and may have been susceptible to error. However, the use of a repeated measures design does minimize the influence of many of these study limitations. Conclusion These results demonstrate that running with heel lifts reduce peak PFJS and PF stress impulse with a trend for decreased peak quadriceps force. Additionally, runners impacted the ground with the ankle in a less dorsiflexed position with a center of pressure more anterior at initial contact. There was no difference in step length, cadence, knee flexion at initial contact or at peak during stance. The utilization of heel lifts may be beneficial in reducing PFJS variables in running. REFERENCES 1. Dutton RA, Khadavi MJ, Fredericson M. Patellofemoral pain. Phys Med Rehabil Clin N Am. 2016;27:31-52. 2. Farrokhi S, Keyak JH, Powers CM. Individuals with patellofemoral pain exhibit greater patellofemoral joint stress: a finite element analysis study. Osteoarthr Cartilage. 2011;19(3):287-294. 3. Wood L, Muller S, Peat G. The epidemiology of patellofemoral disorders in adulthood: A review of general practice morbidity recording. Prim Health Care Res Dev. 2011;12(2):157-164. 4. Glaviano NR, Kew M, Hart JM, Saliba S. Demographic and epidemiological trends in patellofemoral pain. Int J Sports Phys Ther. 2015;10(3):281-290. 5. Rothermich MA, Glaviano NR, Li J, Hart JM. Patellofemoral pain epidemiology, pathophysiology, and treatment options. Clin Sports Med. 2015;34:313327. 6. Kaya D, Citaker S, Kerimoglu U, et al. Women with patellofemoral pain syndrome have quadriceps femoris volume and strength deficiency. Knee Surg Sport Tr A. 2011;19(2):242-247. 7. Boling MC, Padua DA, Creighton RA. Concentric and eccentric torque of the hip musculature in

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individuals with and without patellofemoral pain. J Athl Training. 2009;44(1):7-13. Brechter JH, Powers CM. Patellofemoral stress during walking in persons with and without patellofemoral pain. Med Sci Sport Exerc. 2002;34(10):1582-1593. Draper CE, Fredericson M, Gold GE, et al. Patients with patellofemoral pain exhibit elevated bone metabolic activity at the patellofemoral joint. J Orthop Res. 2012;30(2):209-213. Ho KY, Keyak JH, Powers CM. Comparison of patella bone strain between females with and without patellofemoral pain: a finite element analysis study. J Biomech. 2014;47:230-236. Kernozek TW, Vannatta CN, van den Bogert AJ. Comparison of two methods of determining patellofemoral joint stress during dynamic activities. Gait Posture. 2015;42(2):218-222.

12. Willson JD, Ratcliff OM, Meardon SA, Willy RW. Influence of step length and landing pattern on patellofemoral joint kinetics during running. Scand J Med Sci Sport. 2015;25(6):736-743. 13. Teng HL, Powers CM. Sagittal plane trunk posture influences patellofemoral joint stress during running. J Ortho Sport Phys. 2014;44(10):785-792. 14. Vannatta CN, Kernozek TW. Patellofemoral joint stress during running with alterations in foot strike pattern. Med Sci Sport Exerc. 2015;47(5):1001-1008. 15. Connolly KD, Ronsky JL, Westover LM, Kupper JC, Frayne R. Differences in patellofemoral contact mechanics associated with patellofemoral pain syndrome. J Biomech. 2009;42:2802-2807. 16. Lenhart RL, Thelen DG, Wille CM, Chumanov ES, Heiderscheit BC. Increasing running step rate reduces patellofemoral joint forces. Med Sci Sport Exerc. 2014;46(3):557-564. 17. Roos PE, Barton N, van Deursen RWM. Patellofemoral joint compression forces in backward and forward running. J Biomech. 2012;45:1656-1660. 18. Cavanagh PR, Lafortune MA. Ground reaction forces in distance running. J Biomech. 1980;13(5):397-406. 19. Kulmala JP, Avela J, Pasanen K, Parkkari J. Forefoot strikers exhibit lower running-induced knee loading than rearfoot strikers. Med Sci Sport Exerc. 2013;45(12):2306-2313. 20. Almeida MO, Davis IS, Lopes AD. Biomechanical differences of foot-strike patterns during running: a systematic review with meta-analysis. J Ortho Sport Phys. 2015;45(10):738-755. 21. Williams DSB III, Green GH, Wurzinger B. Changes in lower extremity movement and power absorption during forefoot striking and barefoot running. Int J Sports Phys Ther. 2012;7(5):525-532.

22. Daoud AI, Geissler GJ, Wang F, Saretsky J, Daoud YA, Lieberman DE. Foot strike and injury rates in endurance runners: a retrospective study. Med Sci Sport Exerc. 2012;44(7):1325-1334. 23. Cheung RT, Davis IS. Landing pattern modification to improve patellofemoral pain in runners: a case series. J Ortho Sport Phys. 2011;41(12):914-919. 24. Weber M, Niemann M, Lanz R, Muller T. Nonoperative treatment of acute rupture of the achilles tendon: results of a new protocol and comparison with operative treatment. Am J Sport Med. 2003;31(5):685-691. 25. Farris DJ, Buckeridge E, Trewartha G, McGuigan MP. The effects of orthotic heel lifts on Achilles tendon force and strain during running. J Appl Biomech. 2012;28(5):511-519. 26. Nakanowatari T, Suzukamo Y, Izumi SI. The effectiveness of specific exercises approach or modifiable heel lift in the treatment of functional leg length discrepancy in early post-surgery inpatients after total hip arthroplasty: a randomized controlled trial with a probe design. Phys Ther Res. 2016;19:3949. 27. van den Bogert, AJ, Geijtenbeek T, Even-Zohar O, Steenbrink F, Hardin EC. A real-time system for biomechanical analysis of human movement and muscle function. Med Biol Eng Comput. 2013;51(10):1069-1077. 28. Delp SL, Loan JP, Hoy MG, Zajac FE, Topp EL, Rosen JM. An interactive graphics-based model of the lower extremity to study orthopaedic surgical procedures. IEEE Trans Biomed Eng. 1990;37(8):757767. 29. Erdemir A, McLean S, Herzog W, van den Bogert AJ. Model-based estimation of muscle forces exerted during movements. Clin Biomech. 2007;22(2):131-154. 30. van Eijden TM, de Boer W, Weijs WA. The orientation of the distal part of the quadriceps femoris muscle as a function of the knee flexion-extension angle. J Biomech. 1985;18(10):803-809. 31. Rooney BD, Derrick TR. Joint contact loading in forefoot and rearfoot strike patterns during running. J Biomech. 2013;46(13):2201-2206. 32. Lyght M, Nockerts M, Kernozek TW, Ragan R. Effects of foot strike and step frequency on Achilles tendon stress during running. J Appl Biomech. 2016;32(4):365-372. 33. Noehren B, Scholz J, Davis I. The effect of real-time gait retraining on hip kinematics, pain and function in subjects with patellofemoral pain syndrome. Br J Sports Med. 2010;45(9):691-696.

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IJSPT

ORIGINAL RESEARCH

COMPARISON OF HAMSTRING MUSCLE ACTIVATION DURING HIGH-SPEED RUNNING AND VARIOUS HAMSTRING STRENGTHENING EXERCISES Roland van den Tillaar1 Jens Asmund Brevik Solheim, MSc1 Jesper Bencke, PhD2

ABSTRACT Purpose/Background: Several studies have examined the effect of hamstring strength exercises upon hamstring strains in team sports that involve many sprints. However, there has been no cross comparison among muscle activation of these hamstring training exercises with actual sprinting. Therefore, the aim of this study was to examine different hamstring exercises and compare the muscle activity in the hamstring muscle group during various exercises with the muscular activity produced during maximal sprints. Methods: Twelve male sports students (age 25 ± 6.2 years, 1.80 ± 7.1 m, body mass 81.1 ± 15.6 kg) participated in this study. Surface EMG electrodes were placed on semimembranosus, semitendinosus and biceps femoris to measure muscle activity during seven hamstrings exercises and sprinting together with 3D motion capture to establish at what hip and knee angles maximal muscle activation (EMG) occurs. Maximal EMG activity during sprints for each muscle was used in order to express each exercise as a percentage of max activation during sprinting. Results: The main findings were that maximal EMG activity of the different hamstring exercises were on average between 40-65% (Semitendinosus), 18-40% (biceps femoris) and 40-75% (Semimembranosus) compared with the max EMG activity in sprints, which were considered as 100%. The laying kick together with the Nordic hamstring exercises and its variations had the highest muscle activations, while the cranes showed the lowest muscle activation (in all muscles) together with the standing kick for the semimembranosus. In addition, angles at which the peak EMG activity of the hamstring muscle occurs were similar for the Nordic hamstring exercises and different for the two crane exercises (hip angle), standing kick (hip angle) and the laying kick (knee angle) compared with the sprint. Conclusions: Nordic hamstring exercises with its variation together with the laying kick activates the hamstrings at high levels and at angles similar to the joint angles at which peak hamstring activation occurs during sprinting, while cranes did not reach high levels of hamstring activation compared with sprinting. Level of Evidence: 1b Key words: Electromyography, muscle activity, hamstring, sprint

1

Department of Sport Sciences and Physical Education, Nord University, Levanger, Norway 2 Human Movement Analysis Laboratory, Dept. of Orthopaedic Surgery, Copenhagen University Hospital, Amager-Hvidovre, Denmark

CORRESPONDING AUTHOR Roland van den Tillaar, PhD Department of Sports Sciences and Physical Education Nord University Odins veg 23, 7603 Levanger Norway Phone: +47-5767 1883 Fax: 0047-7411 2001 E-mail: roland.v.tillaar@nord.no

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INTRODUCTION Hamstring strain injuries are one of the most frequently occurring injuries in sports, representing approximately 12-24% of all athletic injuries.1-3 There is a high prevalence of hamstring strain injuries in many sports, including soccer, 4,5 Australian football, 6 American football7 and sprinting. High-speed running is a common denominator among these activities and is the activity accounting for the majority of hamstring strains.8 The hamstring muscles are mostly active during the late swing phase and the start of the stance phase.9 During sprinting the hamstring muscles contract eccentrically during the late swing and late stance phases to control knee and hip extension, which makes the risk of hamstring injury greatest during those phases.10,11 Yu, et al.10 argued that hamstring strain injuries may be most likely to occur at the muscle tendon junction during the late stance phase, and in the muscle belly during the late swing phase. Different risk factors for these hamstring strains were identified, which can be categorized in two categories: 1) unmodifiable factors like age,12 previous hamstring injury2,12-14 and 2) modifiable factors: hamstring weakness,14,15, muscle fatigue,16 decreased flexibility,17 poor running technique and altered neuromuscular function.18 Since it is not possible to affect the unmodifiable factors, only the modifiable factors are of interest when aiming to avoid a future hamstring strain. Hamstring weakness is one of the most common risk factors associated with hamstring injuries. It has been suggested that hamstrings can produce sufficient force to counter the force produced by the quadriceps during various movements.15 Thereby, a stronger muscle could provide adequate protection from stretching and tearing the muscle fibers.8 Several training studies were conducted to investigate how to decrease weakness and increase neurological control. Guex, et al.8 presented a conceptual framework for strengthening the hamstring and for developing specific exercises. They proposed six key parameters to be considered when developing exercises: contraction type, load, range of motion, angular velocity, uni/bilateral exercises, and the kinetic chain. Guex, et al.8 concluded that the hamstring strength exercises used should be specific to simu-

late the power developed by the hamstring during the late swing phase of sprinting. However, none of the existing training studies directly compared the hamstring activity during the different strength training exercises and the activity during the sprint phase, which makes it difficult to determine whether the muscle training is specific enough for high speed running. Furthermore, it is not known if the angles at which the different exercises are conducted are similar to the position of the limb during late swing phase and thereby the hamstring length at peak tension. At present, information is limited regarding what resistance training maximally activates the hamstring, which exercise is the most specific related to sprint and targets the hamstrings strength in the most vulnerable position that occurs in high speed running: the angles seen in late swing phase, that occur with a fast eccentric contraction. Training the hamstring muscle group is critical for performance and plays an important role in hamstring injury prevention. The Nordic hamstring exercises is commonly used for prevention of hamstring strains. It is an exercise that is suggested to target the hamstrings effectively and has been shown to prevent hamstring strains.19 However, whether the angles at which the exercise is conducted are similar to the late swing phase has not been studied, and it is not known if hamstring muscle activity is high enough during this exercise to elicit a strength training stimulus, which has been suggested to be at least 70% of a maximal voluntary contraction.20-22 There may be more effective strength exercises like some explosive exercises that may better target the hamstring muscles, and at more specific angles and higher movement velocities that resemble the demands of the late swing and early stance phase in high speed running. Therefore, the aim of this study was to examine different hamstring exercises and compare the muscle activity in the hamstring muscle group during various exercises with the muscular activity produced during maximal sprints. The gained information regarding muscle activity during the different hamstring strength exercises could help trainers, physiotherapists, and athletes to develop strength training programs that could target the hamstrings in an effective way to gain hamstring strength and potentially reduce the chance of hamstring strain during high-speed running.

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MATERIALS AND METHODS To compare maximal electromyography (EMG) activity for the hamstring muscle group, during a maximal sprint with several types of hamstring strength exercises, seven popular hamstring exercises were chosen. The exercises were able to be performed without much specific strength equipment. Some of the chosen exercises, such as the Nordic hamstring exercise, were selected from existing research papers.27, 28 In addition, some modifications to the Nordic hamstring exercise that have been suggested to target the hamstrings even more than the standard Nordic hamstring exercise, were included as well as some less well investigated exercises that simulate higher movement velocities seen in high speed running. All the exercises focused on targeting the hamstrings in lengthened conditions, which represents the risk situation the hamstrings undergo during the running cycle. SUBJECTS Twelve male sports students (age 25±6.2 years, 1.80±7.1 m, body mass 81.1±15.6 kg) participated in the study. Participants were excluded from the study if they had a former hamstring strain (the previous year), or if they had muscular pain or illness that could reduce their effort under each exercise. All participants were familiar with resistance training of the lower extremity. The participants were asked to refrain from any heavy strength training targeting the lower body during the 48 hours before testing, in order to ensure that they were free from strains and well trained. Before testing, a written consent was contained from the participants. The study was conducted with approval of the Regional Committee for Medical Research Ethics and conformed to the latest revision of the Declaration of Helsinki. Procedures One to two weeks before testing day each subject had a familiarization session with the different exercises and the sprint on a non-motorized treadmill. On testing day, the subjects were briefed about the exercise order. The sprint was always conducted first (after warm-up) followed by the seven hamstring exercises, which were performed in a randomized order for each subject to avoid the order effect due to fatigue. Before the warm-up, the hamstring area

of the right leg was shaved, making the electrode adherence faster. After shaving the leg, the subjects performed a general warm up: 15 min of running on a non-motorized treadmill. Following the warmup, the subjects were allowed five minutes of rest, where they were allowed to drink water. During this rest, electrodes and 21 retroreflective markers were placed on the hamstring muscles and anatomical landmarks. The test started with a sprint wearing their regular running shoes on the Woodway Curve 2.0 (Woodway Inc., Waukesha, USA). This is a non-motorized treadmill with curved running surface, which makes it possible for the subjects to run upright and at their own controlled pace. Furthermore, it made it possible to easily measure maximal peak velocity together with 3D kinematics and muscle activity. After the sprint the subject had five minutes rest before performing one of the seven hamstring strength exercises. The different exercises were: a) the laying hamstring kick, b) the standing hamstring kick, c) Nordic hamstring, d) Nordic hamstring with return, e) Nordic hamstring + bump, f) Hamstring cranes without return, and the g) Hamstring cranes with return exercise. See Figure 1 for the description and performance of each exercise. Limiting the test to three repetitions per exercise, randomization of the exercise order, and five minutes of recovery1 provided between the exercises were employed to reduce fatigue and an order effect. Measurements Electromyography (EMG) was used to quantify muscle activity during the sprint and the various exercises. Wireless EMG was recorder by using a Musclelab 6000 system and analyzed by MusclelabTM v10.73 software (Ergotest Technology AS, Langesund, Norway). Before placing the gel coated selfadhesive electrodes (Dri-Stick Silver circular sEMG Electrodes AE-131, NeuroDyne Medical, USA), the skin was shaved, abraded and washed with alcohol. The electrodes (11 mm contact diameter and a 2 cm center-to-center distance) were placed along the presumed direction of the underlying muscle fiber according to the recommendations by SENIAM 23. The electrodes were placed on the right leg on the muscle belly of the biceps femoris, semitendinosus and semimembranosus. The raw EMG signals, sam-

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Figure 1. Performance of the different hamstring exercises. (A) Laying kick: lay on back with on shoulders, hips, and right heel on the ground, kick left heel up, in order to lift right foot off the ground and land on it again (B) Standing kick: stand on left foot, lift right knee and then kick out rapidly with the right foot. (C) Nordic hamstrings: with the feet held by a belt, lean forward with straight hips and back, until unable to hold, release and absorb forces with the hands in an eccentric push up motion. (D) Nordic with return: Same set up as (C), lean forwards with straight hips until unable to hold any longer, and return to the upright starting position. (E) Nordic with bump: lean forwards at the limit of your ability to hold, then move the 5kg weight straight forwards and back as fast as possible. (F) Cranes: ex hips to 90 degrees. Then extend knees until unable to hold it anymore, absorb forces with the hands in an eccentric push up motion. (G) Cranes with return: ex hips to 90 degrees. Then extend knees until unable to hold any longer, and return to the starting position. The International Journal of Sports Physical Therapy | Volume 12, Number 5 | October 2017 | Page 721

pled at 1000 Hz were amplified and filtered using a preamplifier located as close to the pickup point as possible directly connected to the electrodes. The signals were bandpass filtered (fourth-order Butterworth filter) with cut-off frequencies of 20 Hz and 500 Hz. The preamplifier had a common mode rejection ratio of 100 dB. The EMG signals were converted to root mean square (RMS) EMG signals using a hardware circuit network (frequency response 20 - 500 kHz, integrating moving average filter with 100 ms width, total error ± 0.5%). In this study, a comparison of muscle activation during the various exercises was investigated in relation to the maximal EMG activity that occurred during a maximal sprint. The peak RMS converted and filtered data was obtained from the hamstring exercises and presented as percentage of the maximum activation. The peak RMS converted and filtered data from the muscles during the sprint was used as reference (100%). A three-dimensional (3D) motion capture system (Qualysis, Gothenburg, Sweden) with eight cameras operating with a frequency of 500 Hz was used to track reflective markers, creating a 3D positional measurement. The markers were placed on spinous processes of the fifth lumbar vertebrae, one on each side of the body on lateral tip of the acromion, the iliac crests, greater trochanters, on the lateral and medial condyles of the knee, on the lateral and medial malleolei, the distal ends of metatarsals I and V. Segments of the feet, lower and upper leg, pelvis and trunk were made in Visual 3D v5 software (C-Motion, Germantown, MD, USA). Joint angles were measured during the sprint and all seven exercises. 3D motion capture data was synchronized with the wireless EMG recordings. The hip and knee joint angles at which maximal muscle activation of the biceps femoris, semitendinosus and semimembranosus occurred were recorded, and were used for further analysis. STATISTICAL ANALYSIS To assess differences in kinematics and EMG activity during the sprint and the seven exercises, a One-way ANOVA with repeated measures for each of three muscles was used. In addition, to compare the kinematics (knee and hip joint angles) at which maximal muscle activity for each muscle occurred in the sprint and the seven exercise a 3 (muscles:

semitendinosus, semimembranosus and biceps) x 8 (exercise) with repeated measures performed. If the sphericity assumption was violated the GreenhouseGeisser adjustments of the p-values were reported in the results. Post hoc test using Holm-Bonferroni probabilities adjustment was used to locate significant differences. The level of significance was set at p≤0.05. For statistical analysis purposes SPSS Statistics v21 (SPSS, Inc., Chicago, IL) was used. All results are presented as means ± standard deviations and effect size was evaluated with (Eta partial squared) where 0.01<η2<0.06 constitutes a small effect, a medium effect when 0.06<η2<0.14 and a large effect when η2>0.14 24. RESULTS The maximal sprint velocity on the non-motorized treadmill was 22.5 ± 2.0 km/t, Significant differences in EMG activity for the Semitendinosus (F = 9.28, p<0.001, η2 = 0.48), Semimembranosus (F =14.1 p < 0.001, η2 = 0,56) and Biceps femoris (F = 47.45, p < 0.001, η2 = 0.81) were found between the sprint and the seven exercises. Post hoc comparison showed that the maximum EMG activity during sprinting was significantly higher compared with all other exercises for the semitendinosus and biceps femoris, while for the semimembranosus the laying kick was not significantly different from the sprint (Figure 2). In addition, the semimembranosus EMG activity was also significantly higher during the laying kick compared with the standing kick, and the two cranes exercises (Figure 2). For the semitendinosus and biceps femoris the maximal EMG activity during the crane and the crane with return were significantly lower than the three different Nordic hamstrings exercises. For the semimembranosus only the EMG activity of the cranes were significantly lower than the three Nordic hamstring exercises (Figure 2). No significant effect between the muscles were found for the hip (F =0.79, p= 0.47, η2=0.14), and knee angle (F =0.46, p= 0.64, η2=0.07) at which the maximal EMG activity occurred. However, the hip (F =9.1, p<0.001, η2=0.65) and knee joint angles (F = 13.0, p< 0.001, η2=0.69) at which the maximal EMG activity occurred was significantly different between the exercises (Figure 3 and Table 1). Post hoc comparison showed that the knee angle

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standing kick compared with the sprints for all three muscles (Table 1). No significant interaction effect was found for the occurrence at which the maximal EMG activity occurred for the hip (F =0.23, p= 0.99, η2=0.04) and knee joint angles (F =.52, p= 0.98, η2=0.08). DISCUSSION The aim of this study was to compare hamstring muscles activity during different hamstring strengthening exercises with the hamstring muscles activation during a maximal sprint. The main findings were that maximal EMG activity of the different hamstring exercises were on average between 40-65% (Semitendinosus), 18-40% (biceps femoris) and 40-75% (Semimembranosus) of the max EMG activity produced by the hamstrings during a sprint. Cranes showed the lowest muscle activation (in all muscles) together with the standing kick for the semimembranosus (Figure 2). In addition, angles at which the peak EMG activity of the hamstring muscles occurred differed between the two crane exercises (hip angle), standing kick (hip angle) and the laying kick (knee angle) when compared with the sprint.

Figure 2. Maximum EMG activity for semitendinosus, semimembranosus, and biceps femoris during the different exercises (%) related to the sprint (100%). *Indicates a significant difference between this EMG activity and to the right of the arrow on a (p<0.05) †Indicates a significant difference in EMG activity between these two exercises (p<0.05)

at which maximal EMG occurred was significantly lower (more knee flexion) in the laying kick for all three muscles compared with the knee joint angle during the sprints. In addition, the knee angle at which maximal EMG of the biceps occurred during the standing kick was significantly greater (less knee flexion) than the angle during the sprints (Table 1). The hip angle of maximal EMG was significantly greater (less hip flexion) for the cranes and cranes with return and lower (more hip flexion) for the

Analyses of hamstring activation reveal that the maximal sprint resulted in the highest muscle activity for the semitendinosus and biceps femoris when compared to all of the hamstring exercises. For the semimembranosus only the laying kick had no significant difference in level of activation with the sprint, while maximal activation during the other exercises was lower than activation during the sprint. It was expected that hamstring activation during the sprints would be the highest since it involves rapid hip and knee joint movements that utilizes the hamstring to a large degree. Previous authors 25-27 have found that hamstring muscles are most active during the late swing phase of the sprint, in order to slow the forward moving limb. During this part of the running gait cycle, the hamstring muscles work mostly eccentrically, therefore the authors’ chose different hamstring strength exercises also suggested to eccentrically stimulate the hamstrings. However, most of the studied exercises reported an EMG activity lower than 70% of maximal EMG activity during sprint.

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Figure 3. The angles (+/-SD) at maximal EMG activity for the hip and knee joints, averaged over all three muscles for each hamstring exercise and sprint. *Indicates a significant difference for hip joint angle for this exercise with the sprints (p<0.05) †Indicates a significant difference for knee joint angle between this exercise and the sprints on a (p<0.05)

Table 1. Hip and knee joint angles at which maximal EMG activity was recorded of the three muscles during sprint and the seven hamstring strength exercises. All values are reported as degrees, +/- standard deviations

Only the semitendinosus during the three Nordic exercises the and the laying kick demonstrated an average activation of respectively around 70% and 80% and was not significantly different from the sprint. It has been suggested that in order to gain strength in a muscle, an activity has to be at least 70% of a maximal voluntary contraction. 20,22 In the present study, no maximal voluntary contractions were measured, rather activity during exercises were related to the maximal contractions demonstrated

during sprints. In support of this methodology, Jönhagen, et al. 25 showed that maximal voluntary contractions in the hamstring were equal to maximal muscle activation during maximal sprints. None of the investigated exercises in the present study reached the level of activation needed for strength gain (70%) for the biceps femoris (Figure 2). Muscle activity during the two crane exercises and the standing kick were also not of a high enough intensity to be a strengthening stimulus for any of the muscles.

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Despite the relatively low levels of muscle activation (≤70%) during the Nordic hamstrings exercises several recent studies have shown that training the Nordic hamstring exercise can increase strength and muscle activation of the hamstrings.28,29 Bourne, et al.28 showed that Nordic hamstring exercise training promoted the elongation of the fascicles of the biceps femoris long head while it did not promote hypertrophy of the biceps femoris long head. They found that it preferentially developed hypertrophy of the semitendinosus. This is in accordance with the present study that shows activation levels in the semitendinosus that reached almost 70% compared with the biceps femoris of only 40% when compared to values during sprinting. Delahunt, et al.29 found similar average percentage EMG levels for the semitendinosus (65% of eccentric MVC) in the Nordic hamstring exercise, as in the present study. However, after six weeks of Nordic hamstring exercise training the subjects increased this percentage to 80% of eccentric MVC. In the present study some subjects had much training experience with the chosen hamstring exercises, while others did not have as much experience. This may have influenced the variation in EMG activity percentage between subjects during these exercises as shown by the large standard deviations (Figure 2). It was expected that the hamstring activity would be higher in the modifications of the Nordic hamstring exercise (Nordic with return and Nordic with bump) than the traditional Nordic hamstring exercise, especially the Nordic with bump. By leaning forwards as far as possible the subject could hold their body with the hamstring muscles and then add the movement of pushing and pulling a 5 kg weight (Figure 1), which was projected to increase the activity of the hamstring muscles even more. However, this was not the case. An explanation for these findings may be that the subjects did not lean as far forward during the modified Nordic hamstrings exercises as shown in the lower knee angles achieved during the exercise (Table 1 and Figure 3). This causes lower initial work for hamstrings, but the extra weight that has to be pushed, or the return movement compensates for this decrease in leaning. The same was found between the cranes and the cranes with return i.e. less shifting forward in the cranes with return (lower knee angle) so that the subjects could be sure that they had the

strength to return to starting position. This resulted in the same maximal EMG activation during these two crane exercises. It seems that the level of maximal activation determines the degree of forward lean during these variations of Nordic Hamstring exercise, as the joint angles are similar, and thus these modified Nordic hamstring exercises may be used as variations of the traditional Nordic hamstring during training. The lower activity in the cranes exercises were probably caused by the different hip angles (more extended) at which maximal hamstring activity was measured as compared to the sprints (Table 1, Figure 3). During the crane exercises subjects first have to flex their hips. This increases the load on the hamstring due to the weight of the trunk that is moving toward horizontal. From there subjects move forwards, while the trunk is maintained horizontally. This probably causes that the hip angle at which the maximal hamstring EMG activity was measured to occur at another hip angle, while the knee angles were comparable with the Nordic exercises (Table 1, Figure 3). The alterations in hip angle in the presence of the same knee angle likely resulted in a different effective hamstring muscle length and thereby lowered muscle activity that was measured (Figure 2). The standing kick did cause similar, low-level muscle activation as the cranes (Figure 2), which was probably caused by the absence of an added weight that could load the hamstrings. In all other exercises the trunk causes extra load to the hamstrings, as compared with the sprint, during which the load on the hamstrings is caused by the lower and upper limb movements. The standing kick was included to investigate whether kicking in a position of higher knee extension and flexion than in sprinting would cause an extra load to the hamstrings. The present data suggests that this was not the case. However, adding extra weights around the ankle joint may potentially have increased the hamstrings activity to a level comparable to the other exercises, but this was not investigated. The maximal hamstring activity during sprint was measured for all three muscles at around the same time in the late swing phase, which was comparable with earlier studies 25-27,30. The angles of Nordic hamstrings and modified hamstring exercises at which maximal hamstring activity occurred was similar to

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the maximal activity seen during sprints indicating that these exercises target the hamstring muscles at the right part of the running cycle when following the principle of specificity. The laying kick exercise produced similar EMG activity to the Nordic hamstring exercises, and for the semitendinosus reached almost the same activity level as in the sprints indicating that this also could be a good hamstring strength exercise. However, in the present study the knee flexion angle was much more flexed for this exercise compared to the sprints, which could target the hamstring muscle at the wrong angle. Yet, subjects were not familiar with this exercise and were perhaps therefore a bit reluctant to put a potentially greater load on the hamstrings by putting the foot more distally on the ground and thereby decreasing knee flexion angle to a degree comparable to the sprint knee angles. With this variation, the exercise could target the hamstring muscle closer angles to those used during sprinting and possibly increase maximal EMG hamstring activity. When comparing EMG hamstring activity between the laying kick and the Nordic hamstring exercise there were no differences found, while in the laying kick only one leg is trained and in the Nordic hamstring exercises both legs were used. To increase maximal EMG hamstring activity during the Nordic exercises it is possible to perform them with only one leg fastened. This would probably increase the EMG activity to reach a level (>70% of maximal voluntary contraction) and a greater potential for strength gain of these muscles may be possible. Future studies should investigate hamstring muscle activity in these modified Nordic hamstring exercises with one leg fastened as well as the laying kick, with a lower knee flexion to see if they reach high enough muscle activity levels. Furthermore, training studies with the laying kick exercise should be conducted to investigate if this exercise could have the same or even better results in strengthening the hamstring muscles and to reduce the occurrences of hamstrings strains in sports involving sprints. CONCLUSION The results of the current study indicate that among the selected exercises the Nordic hamstring exercise (and its variations) activates the hamstrings at high levels and at angles similar to the joint angles

at which peak hamstring activation occurred during sprinting, which may in part explain the great potential for hamstring injury prevention shown in other studies. Furthermore, the results show that the explosive laying kick exercise yielded similarly high hamstring activation levels but the knee joint angle was not specific to the angle at which highest activation occurred during the sprint. This exercise must be studied more before the potential as a prophylactic exercise can be determined. REFERENCES 1. Ebben WP, Feldmann CR, Dayne A, et al. Muscle activation during lower body resistance training. Int J Sports Med. 2009;30(1):1-8. 2. Schmitt B, Tim T, McHugh M. Hamstring injury rehabilitation and prevention of reinjury using lengthened state eccentric training: a new concept. Int J Sports Phys Ther. 2012;7(3):333-341. 3. Woods C, Hawkins RD, Maltby S, et al. The Football Association Medical Research Programme: an audit of injuries in professional football--analysis of hamstring injuries. Br J Sports Med. 2004;38(1):3641. 4. Ekstrand J, Gillquist J. Soccer injuries and their mechanisms: a prospective study. Med Sci Sports Exerc. 1983;15(3):267-270. 5. Inklaar H. Soccer injuries. I: Incidence and severity. Sports Med. 1994;18(1):55-73. 6. Orchard JW, Seward H, Orchard JJ. Results of 2 decades of injury surveillance and public release of data in the Australian Football League. Am J Sports Med. 2013;41(4):734-741. 7. Elliott MC, Zarins B, Powell JW, et al. Hamstring muscle strains in professional football players: a 10-year review. Am J Sports Med. 2011;39(4):843-850. 8. Guex K, Millet GP. Conceptual framework for strengthening exercises to prevent hamstring strains. Sports Med. 2013;43(12):1207-1215. 9. Mero A, Komi PV. Electromyographic activity in sprinting at speeds ranging from sub-maximal to supra-maximal. Med Sci Sports Exerc. 1987;19(3):266274. 10. Yu B, Queen RM, Abbey AN, et al. Hamstring muscle kinematics and activation during overground sprinting. J Biomech. 2008;41(15):3121-3126. 11. Bahr R, Holme I. Risk factors for sports injuries--a methodological approach. Br J Sports Med. 2003;37(5):384-392. 12. Daly C. Sprint-related hamstring injuries. SportEX Med. 2013(58):20-25.

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13. Engebretsen AH, Myklebust G, Holme I, et al. Intrinsic risk factors for hamstring injuries among male soccer players: a prospective cohort study. Am J Sports Med. 2010;38(6):1147-1153. 14. Agre JC. Hamstring injuries. Proposed aetiological factors, prevention, and treatment. Sports Med. 1985;2(1):21-33. 15. Foreman TK, Addy T, Baker S, et al. Prospective studies into the causation of hamstring injuries in sport: A systematic review. Phys Ther Sport. 2006;7(2):101-109. 16. Makaruk B, Makaruk H. Changes to flexibility of the hamstring in sprinters in the context of prevention. Pol J Sport Tourism. 2009;16(3):152-154. 17. Jönhagen S, Ackermann P, Saartok T. Forward lunge: a training study of eccentric exercises of the lower limbs. J Strength Cond Res. 2009;23(3):972-978. 18. Devlin L. Recurrent posterior thigh symptoms detrimental to performance in rugby union: predisposing factors. Sports Med. 2000;29(4):273-287. 19. van der Horst N, Smits D-W, Petersen J, et al. The Preventive Effect of the Nordic Hamstring Exercise on Hamstring Injuries in Amateur Soccer Players: A Randomized Controlled Trial. Am J Sports Med. 2015;43(6):1316-1323. 20. Andersen LL, Magnusson SP, Nielsen M, et al. Neuromuscular activation in conventional therapeutic exercises and heavy resistance exercises: implications for rehabilitation. Phys Ther. 2006;86(5):683-697. 21. Fry AC. The role of resistance exercise intensity on muscle fibre adaptations. Sports Med. 2004;34(10):663-679. 22. Boren K, Conrey C, Le Coguic J, et al. Electromyographic analysis of gluteus medius and

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gluteus maximus during rehabilitation exercises. Int J Sports Phys Ther. 2011;6(3):206-223. Hermens HJ, Freriks B, Disselhorst-Klug C, et al. Development of recommendations for SEMG sensors and sensor placement procedures. J electromyogr Kinesiol. 2000;10(5):361-374. Cohen J. Statistical Power Analysis for the Behavioral Sciences. Hillsdale, NJ, England: Lawrence Erlbaum Associates; 1988. Jönhagen S, Ericson MO, Nemeth G, et al. Amplitude and timing of electromyographic activity during sprinting. Scand J Med Sci Sports. 1996;6(1):15-21. Chumanov ES, Heiderscheit BC, Thelen DG. Hamstring musculotendon dynamics during stance and swing phases of high-speed running. Med Sci Sports Exerc. 2011;43(3):525-532. Higashihara A, Ono T, Kubota JUN, et al. Functional differences in the activity of the hamstring muscles with increasing running speed. J Sports Sci. 2010;28(10):1085-1092. Bourne MN, Duhig SJ, Timmins RG, et al. Impact of the Nordic hamstring and hip extension exercises on hamstring architecture and morphology: implications for injury prevention. Br J Sports Med. 2016. Delahunt E, McGroarty M, De Vito G, et al. Nordic hamstring exercise training alters knee joint kinematics and hamstring activation patterns in young men. Eur J Appl Physiol. 2016;116(4):663-672. Higashihara A, Nagano Y, Ono T, et al. Relationship between the peak time of hamstring stretch and activation during sprinting. Eur J Sport Sci. 2016;16(1):36-41.

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IJSPT

ORIGINAL RESEARCH

THE EFFICACY OF ANGLE-MATCHED ISOKINETIC KNEE FLEXOR AND EXTENSOR STRENGTH PARAMETERS IN PREDICTING AGILITY TEST PERFORMANCE Matt Greig, PhD¹ James Naylor¹

ABSTRACT Background: Agility is a fundamental performance element in many sports, but poses a high risk of injury. Hierarchical modelling has shown that eccentric hamstring strength is the primary determinant of agility performance. Purpose: The purpose of this study was to investigate the relationship between knee flexor and extensor strength parameters and a battery of agility tests. Study Design: Controlled laboratory study. Methods: Nineteen recreational intermittent games players completed an agility battery and isokinetic testing of the eccentric knee flexors (eccH) and concentric knee extensors (conQ) at 60, 180 and 300⬚·s-1. Peak torque and the angle at which peak torque occurred were calculated for eccH and conQ at each speed. Dynamic control ratios (eccH:conQ) and fast:slow ratios (300:60) were calculated using peak torque values, and again using angle-matched data, for eccH and conQ. The agility test battery differentiated linear vs directional changes and prescriptive vs reactive tasks. Results: Linear regression showed that eccH parameters were generally a better predictor of agility performance than conQ parameters. Stepwise regression showed that only angle-matched strength ratios contributed to the prediction of each agility test. Trdaitionally calculated strength ratios using peak torque values failed to predict performance. Angle-matched strength parameters were able to account for 80% of the variation in T-test performance, 70% of deceleration distance, 55% of 10m sprint performance, and 44% of reactive change of direction speed. Conclusions: Traditionally calculated strength ratios failed to predict agility performance, whereas angle-matched strength ratios had better predictive ability and featured in a predictive stepwise model for each agility task. Level of Evidence: 2c Key words: Agility, hamstring, injury, isokinetic, strength

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Sports Injuries Research Group, Department of Sport & Physical Activity, Edge Hill University, Lancashire, UK

CORRESPONDING AUTHOR Matt Greig, PhD Sports Injuries Research Group, Department of Sport & Physical Activity, Edge Hill University, St. Helens Road, Ormskirk, Lancashire, L39 4QP, United Kingdom Tel: (+44) 01695 584848 Fax: (+44) 01695 584812 E–mail: matt.greig@edgehill.ac.uk

The International Journal of Sports Physical Therapy | Volume 12, Number 5 | October 2017 | Page 728 DOI: 10.16603/ijspt20170728

INTRODUCTION The ability to change direction rapidly has implications for both performance1 and injury risk.2 A hierarchical ordering of anthropometric, cognitive, and knee flexor/extensor strength parameters across a battery of agility tests showed that eccentric hamstring strength was the primary determinant of success.3 To date, the majority of research investigating the predictors of agility performance has focused on markers of leg strength.4,5 This focus within the literature reflects the functional role of eccentric hamstring strength in enhancing neuromuscular control during the foot ground contact phase of cutting activities.6 Strength parameters, as derived from isokinetic testing, have traditionally included peak torque, angle of peak torque, and ipsi-lateral strength ratios. The use of peak concentric quadriceps and concentric hamstring strength was usurped by the ‘functional ratio’,7 which quantifies the ratio of peak eccentric hamstring (eccH) torque to peak concentric quadriceps (conQ) torque. This ratio has greater mechanical specificity to reflect the reciprocal antagonistic muscular function during core skills such as running. However, the use of peak values negates that the quadriceps and hamstrings will exhibit their peak torque at different joint angles,8 and recently anglematched data have been advocated as a means of providing a more functionally relevant measure.9,10 The purpose of the present study was to investigate the relationship between knee flexor and extensor strength parameters and a battery of agility tests. The test battery was designed to incorporate the varied elements of agility, and therefore to differentiate between linear speed, prescriptive and reactive change of direction, and deceleration.3 The range of components influencing agility performance lends itself to a hierarchical ordering of factors, and in this study both the traditional and angle-matched derivations of strength ratios are considered. It was hypothesized that the angle-matched strength ratios would provide a stronger predictor of athletic performance. METHODS Participants Nineteen male intermittent team sports players (mean ± S.D.; age: 22.1 ± 1.9 years; height: 182.9 ± 5.5 cm; body mass: 77 ± 4.9 kg) who competed in

rugby or soccer completed the study. Intermittent team sport players were recruited so that all participants were familiar with the functional challenges posed by the test battery. Additional inclusion criteria required players to be injury free for three months preceding data collection. Participants provided written informed consent with ethical approval granted at the host university departmental ethics committees, and in the spirit of the Helsinki Declaration. No potential conflicts of interest were noted. All testing was conducted between 14:00–16:00 hours in accord with regular competitive demands of these players, and to negate the influence of circadian effects on performance. Agility testing battery The testing battery was comprised of the following: a T-test, a 10 m linear sprint, a reactive change of direction cutting task, and a reactive deceleration task, performed in randomized order and as described in previous applications.3 This battery (Figure 1) was designed to differentiate between prescriptive vs. reactive tasks, linear vs. multi-directional speed, and acceleration vs. deceleration. All agility tests were completed using commercially available photoelectric timing gates (Smartspeed, Fusion Sport, Australia) with testing preceded by a dynamic warm-up and a demonstration of each agility test. Isokinetic profiling All subjects completed isokinetic dynamometry assessments within ±2 weeks of the agility testing (System 3, Biodex Medical Systems, Shirley, NY, USA). Testing comprised of eccentric knee flexor (in reactive eccentric mode) and concentric knee extensor strength at angular velocities of 180, 300, and 60⬚·s-1.11 The dynamometer setup was modified so as to be subject specific, following the manufacturer’s guidelines. The crank axis was aligned with the axis of rotation of the knee joint, and the cuff of the dynamometer’s lever arm was secured around the ankle, proximal to the malleoli. With the subject in the seated position, restraints were applied across the test thigh, proximal to the knee joint so as not to restrict movement, and across the chest. Familiarization trials were completed in each mode and at each speed, with data collection comprising five maximal contractions at each speed.12 The recovery

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Figure 1. The agility testing battery.

phase between maximal efforts was set as passive knee flexion at 10⬚·s-1, requiring no exertion from the subject. There was an allocated 90 seconds rest between sets. Communication to each participant was restricted to informing them of the test speeds with no visual feedback offered. Peak torque (T) and angle of peak torque (θ) were calculated at each speed for both eccH and conQ. The dynamic control ratio (DCR), defined as eccH:conQ was calculated at each test speed using peak torque values. Fast:slow (300:60) ratios were also calculated for both eccH and conQ using peak torque values. The ipsi-lateral eccH:conQ ratio, and the fast:slow ratio were also calculated using angle-matched torque data. All calculations were restricted to the isokinetic phase of movement. Statistical Analyses Agility test performance data and all isokinetic parameters are quantified as mean ± standard deviation. Linear regression analysis was used to quantify the relationship between performance on each agility test with peak torque, and with angle of peak torque at each discrete testing speed (60, 180, 300º·s-1), and for each modality (eccH, conQ).

Multiple linear regression analysis was then used to model agility test performance as a function of peak torque across all testing speeds collectively, for eccH and for conQ. This process was repeated for angle of peak torque across all speeds in each modality. In all cases the correlation coefficient (r) was used to quantify the relative contribution of each factor to agility performance. The value r2 was subsequently calculated to quantify the percentage variation in agility performance that can be accounted for by variation in the isokinetic variable. Finally, and in order to develop a hierarchical ordering of the strength parameters influencing each agility test, a forward stepwise regression model was utilized. Stepwise linear regression provides a means of including multiple variables within a model while simultaneously removing those variables that are not important. The forward selection model employed is initiated with no variables included, and subsequently adding the variable whose insertion gives the most statistically significant improvement of the correlation. This process is repeated until no additional variables improve the model to a statistically significant extent. This process allowed for identification of the singular most important isokinetic

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contributor to agility test performance, defined by the greatest magnitude of r. Additional strength parameters were added in sequence, only if their insertion improved the magnitude of r. The number of model steps is therefore unique to each agility test, and each step is quantified by the correlation coefficient at that level. RESULTS Table 1 summarizes the performance for each agility test, and for each isokinetic analysis parameter. Peak

torque and angle of peak torque are expressed for eccH and conQ at each testing speed. The dynamic control ratio and fast:slow strength ratios are provided for both traditional and angle-specific methods. Angle-matched strength ratios are distinguished with the use of a superscript θ. Table 2 quantifies r2 for the squarelinear correlation of agility test performance as a function (f) of each parameter determined for eccH and conQ. Individual correlation coefficients in eccH peak torque (T)

Table 1. Agility test and isokinetic strength performance of 19 male intermittent team sport players.

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were lowest in the Reactive Cut (r2 ≤ 0.02), and typically greatest in the T-test at all testing speeds. The single highest correlation strength was observed for eccH T180 (r2 = 0.61). Individual correlation coefficients in T were lower for conQ than eccH in all tests with the exception of the Reactive Cut, although values were still small (r2 ≤ 0.10). Correlation coefficients in the angle of peak torque (θ) were also highest for eccH in the T-test (r2 ≤ 0.27), except at the fastest testing speed. As with peak torque, the strength of the individual correlation coefficients was typically greater in eccH than for conQ. When

peak torque was considered across all testing speeds, eccH strength was able to account for up to 62% of variation in T-test performance, but only 2% of Reactive Cut performance. The angle of peak torque across all speeds was able to account for between 7% (10m Sprint) and 44% (T-test) of agility performance in eccH. These values were lower for conQ, with collective peak torque accounting for between 9% (Deceleration) and 24% (T-test) of variation in performance. Angle of peak conQ torque across all speeds was also greatest for T-test (r2 = 0.16), with only 2% of Deceleration performance accounted for.

Table 2. Single and multiple linear regression analyses to quantify the correlation (r2) between isokinetic strength parameters and agility test performance.

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Table 3. A hierarchical linear regression model of isokinetic strength factors influencing agility test performance using a forward stepwise approach.

Table 2 also summarizes a multiple linear regression to quantify the predictive potential of all parameters in peak torque (and at all speeds). With all variables considered, eccH proved a stronger determinant of performance than conQ in the 10m sprint (eccH r2 = 0.33; conQ r2 = 0.18), T-test (eccH r2 = 0.75; conQ r2 = 0.36), and Deceleration test (eccH r2 = 0.45; conQ r2 = 0.09). While the weakest correlations were observed in the Reactive Cut (eccH r2 = 0.16; conQ r2 = 0.20), the greatest correlation was observed between eccentric hamstring strength parameters and T-test performance (r2 = 0.75, p = 0.01). The previous data includes only parameters relating to peak torque, with no consideration of anglematched data. In the next series of regressions the strength parameters were considered as both traditional (using peak torque values), and anglematched. Table 3 presents the hierarchical ordering of factors influencing each agility tests. The original data set included peak torque, angle of peak torque, eccH:conQ and fast:slow ratios (using peak torque and angle-matched data). Angle-matched strength ratios are distinguished with the use of a superscript θ. Stepwise modelling produced a hierarchical model of determinants, with isokinetic parameters able to account for between 44% (Reactive Cut) and 80% (T-test) of the variation in agility test performance.

In the 10m Sprint test the hierarchical model was comprised entirely of variables from the eccH modality. T180 was the primary predictor of 10m Sprint performance, with the fast:slow ratio and θ300 subsequently added. The T-test also had eccH T180 as the primary predictor, with the high speed DCR as a secondary element. Both additional elements added to this model were also in eccH, with θ60 and the fast:slow ratio producing a cumulative r2 = 0.80. The high speed DCR was the primary predictor of Reactive Cut performance, where slow conQ θ60 also appeared in the model as a tertirary predictor. EccH elements also dominated Deceleration performance, with T60, the fast:slow ratio and θ60 the first elements to be included, and θ180 in conQ the final addition to produce a total r2 of 0.70. DISCUSSION The aim of the present study was to investigate the relationship between knee flexor and extensor strength measures and an agility testing battery. The agility tests were designed to differentiate between linear and change of direction speed, prescriptive and reactive drills, acceleration and deceleration. Additional rigour was provided in measures of isokinetic strength with recent research advocating the use of angle-matched analyses to more closely replicate the functional kinesiology of such tasks.9,10

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Considering each agility test as a function of peak torque and angle at peak torque at all test speeds, eccentric hamstring strength proved a stronger predictor of performance in three of the tests and was shown to account for 75% of the variance in the T-test. The hamstrings musculature enhances functionality in both linear and directional change tasks,13 helping to maintain hip extensor torque, assisting dynamic trunk stabilisation, and controlling knee flexion.6 The functional role of the hamstrings in neuromuscular control during the ground contact phase enhances the development of stride frequency,6 and thus the multiple changes of speed and/or direction in the T-test makes most functional use of the hamstrings. In contrast, the lack of relationship with the reactive cut might be attributed to insufficient time to generate muscle force.14 The greater relative contribution to predictive change of direction speed is in line with previous work, where eccentric hamstring strength was able to discriminate between the best and worst T-test performers.15 The strong correlation between T-test performance and eccentric hamstring strength was further analyzed using a forward stepwise regression to develop a hierarchical model of each test. Eccentric hamstring strength at 180⬚·s-1 was the standout contributor, accounting for 61% of the variability in task performance. Peak torque at this mid-range speed was also the primary predictor of 10m sprint (r2 = 0.23, P = 0.24) performance. In contrast, peak torque at the slowest speed of 60⬚·s-1 best predicted deceleration task performance (r2 = 0.32, P = 0.01). This relatively slow isokinetic test speed is most often used in literature considering the correlation between agility and isokinetic strength,6,15 but the present study highlights the task-specific functional demands of strength and the necessity to conduct isokinetic profiles across a range of speeds. In summation, based on this agility battery, slow speed strength best predicts deceleration performance while moderate speed strength is more srongly correlated with tasks emphasising acceleration. This functional relationship has implications for both training and (p)rehabilitation. The hierarchical modelling of factors affecting agility performance failed to include strength ratios calculated using the traditional peak torque values. The

limitation of this dynamic control ratio is the assumption that peak eccentric hamstring and concentric quadriceps torque are co-dependent.8 In contrast, the angle-matched strength ratios were a more powerful predictor of agility performance. The primary contribution from eccentric hamstring strength in predicting agility test performance was supplemented by angle-specific strength ratios. The high speed angle matched dynamic control ratio was the first or second placed parameter in a hierarchical ordering of both the reactive and prescriptive change of direction tasks respectively. In contrast, the linear tasks both exhibited the angle matched fast:slow eccentric hamstring strength ratio as a second predictor of performance. The angle matched fast:slow ratio for eccentric hamstring strength was included in the full hierarchical modelling of three of the agility tests. The impact of the angle-matched dynamic control ratio in change of direction tasks highlights the greater functional relevance, and subsequently greater correlation with athletic performance than traditional strength ratios based on peak torque and independent of joint angle. This stepwise process created a multiple linear regression equation for each agility test, with up to 80% of the variability in performance accounted for. The strongest correlation for the T-test probably reflects the frequency and variety of functional demands of this test, which includes the discrete elements of the other tests in linear acceleration, deceleration, and change of direction. The weakest correlation was observed for the reactive cutting task, most likely reflecting the greater contribution to this test from the psychological strand of the agility model,3,16 which was not considered in the present study. Comparisons with previous literature are limited, slow eccentric knee flexor strength explaining 39% of variance in a change of direction task6 and in a multi-factorial investigation including slow eccentric hamstring strength accounting for ~45% of the variance in the predictive T-test and 5m shuttle run test.15 The higher values reported in the current study are encouraging and reflect a more functional approach to isokinetic profiling, particularly in relation to the testing speed which incorporated profiling up the maximum available 300⬚·s-1. The inclusion of higher speed analyses also enables the use of fast:slow strength ratios, which (when using angle matched data) were consistent factors

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influencing agility task performance. Given the functional role of the hamstring musculature during such tasks,17 the force-velocity relationship warrants greater consideration in conditioning, training the hamstring musculature closer to speeds with functional relevance to the task. The multiple regression coefficients presented in Table 3 are such that the variability in task performance not explained by the strength parameters not included in the present study ranged from 20% in the T-test to 56% in the reactive cut. This highlights the complexity in determining those factors affecting agility, and particularly the ‘perceptual and decision-making factors’ fundamental in reactive agility.16 Incorporating both physical and psychological strands of the agility model into a hierarchical ordering of varying agility tasks would therefore have merit. There is also scope for greater consideration of technique, and it must be acknowledged that the nature and size of the population used in the present study also limits generalization. In the present study soccer and rugby players were grouped as being representative of intermittent team sports. Future research might consider a more rigorous grouping of participants, given potential differences in the agility demands of these sports. Gender disparities in the frequency and severity of anterior cruciate ligament injury 2 and the relevance of agility tasks to common injury mechanisms would also suggest that a comparison of male and female athletes would be beneficial. Exclusion crieteria employed in the current study negated the opportunity to further examine this relationship in participants with a history of knee or hamstring injury. The analysis extended to participants representing differences in gender, level of competition, sport, and injury history would all be valuable contributions. The epidemiological observations of increased injury risk during the latter stages of sports also warrant investigation of whether these correlations might change with fatigue. It must therefore be acknowledged that interpretation of the data presented in the current study should not be generalized beyond a male, non-elite intermittent team sports player, with no previous injury history. CONCLUSIONS Weak correlations across the agility testing battery highlight the varied and distinct technical elements

of each test, such that in profiling agility a battery of tests is advocated. Eccentric hamstring strength typically displayed a stronger correlation coefficeient with agility performance than concentric quadriceps strength, highlighting the functional role of the hamstrings in such tasks. Strength ratios based on peak torque values failed to predict agility performance, whereas angle-matched strength ratios featured prominenetly in predictive stepwise models of performance. The speed of eccentric hamstring strength was also an important factor, advocating profiling at faster, more functional speeds. A combination of strength parameters was able to predict up to 78% of agility performance, but the efficacy and strength of the prediction is task dependent. The use of ipsi-lateral strength ratios has merit, but the fast:slow ratio warrants inclusion also. With a comprehensive isokinetic profile, functionally matched to the athletic task, there is efficacy in predicting agility test performance using isokinetic profiling. REFERENCES 1. Bloomfield J, Polman R, O’Donoghue P. Physical demands of different positions in FA Premier League soccer. J Sports Sci Med. 2007;6(1):63-70. 2. Hewett TE, Ford KR, Hoogenboom BJ, Myer GD. Understanding and preventing ACL injuries: Current Biomechanical and Epidemiological considerations. Am J Sports Phys Therapy. 2010;5(4):234-251. 3. Naylor J, Greig M. A hierarchical model of factors influencing a battery of agility tests. J Sports Med Physical Fitness. 2015;55(11):1329-1335. 4. Young WB, James R, Montgomery L. Is muscle power related to running speed with changes of direction? J Sports Med Phys Fitness. 2002;43:282-288. 5. Young WB, Farrow D. A review of agility: practical applications for strength and conditioning. Strength Cond J. 2006;28:24-29. 6. Jones P, Bampouras T, Marrin K. An investigation into the physical determinants of change of direction speed. J Sports Med Phys Fitness. 2009; 49: 97-104. 7. Dvir Z, Eger G, Halperin N, Shklar A. Thigh muscles activity and ACL insufficiency. Clin Biomech. 1989;4:87-91. 8. Knapik JJ, Wright JE, Mawdsley RH, Braun J. Isometric, isotonic, and isokinetic torque variations in four muscle groups through a range of motion. Phys Ther. 1983;63(6):938-947. 9. Evangelidis PE, Pain MTG, Folland J. Angle-specific hamstring-to-quadriceps ratio: A comparison of

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football players and recreationally active males. J Sports Sci. 2015;33(3):309-319. Cohen DD, Zhao B, Okwera B, Matthews MJ, Delextrat A. Angle-specific eccentric hamstring fatigue after simulated soccer. Int J Sports Physiol Perf. 2015;10:325-331. Greig M. The influence of soccer-specific fatigue on peak isokinetic torque production of the knee flexors and extensors. Am J Sports Med. 2008;36(7):14031409. Brown LE, Weir JP. (2001). ASEP procedures recommendation I: accurate assessment of muscular strength and power. J Exerc Physiol. 2001;4(3):1-21. Brughelli M, Cronin J, Levin G, Chaouachi A. Understanding Change of Direction Ability in Sport: A Review of Resistance Training Studies. Sports Med. 2008;38(12):1045-1063.

14. Cox RH. Sport psychology: Concepts and applications (5th edn.). New York: McGraw Hill; 2002. 15. Chaouachi A, Manzi V, Chaalali A, Wong D, Chamari K, Castagna C. Determinants Analysis of Change-ofDirection Speed in Elite Soccer Players. J Strength Cond Res. 2012;26(10):2667-2676. 16. Sheppard JM, Young, WB. Agility Literature Review: Classifications, training and testing. J Sports Sci. 2006; 24(9):919-932. 17. Verrall GM, Slavotinek JP, Barnes PG, Fon GT, Spriggins AJ. Clinical risk factors for hamstring muscle strain injury: a prospective study with correlation of injury by magnetic resonance imaging. Br J Sports Med. 2001;35(1):435-440.

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IJSPT

ORIGINAL RESEARCH

LOWER EXTREMITY KINEMATICS OF ACL-REPAIRED AND NON-INJURED FEMALES WHEN USING KNEE SAVERS® Whitley J. Stone, PhD1 Scott W. Arnett, PhD, CSCS2 Donald L. Hoover, PT, PhD, CSCS3

ABSTRACT Background: Knee Savers® (KS) are an ergonomic aid purported to lessen the risk of injuries linked to deep squats. While widely used in sports such as baseball and softball, KS have not been tested to determine their effect upon lower extremity kinematics in any population. Purpose: The purpose of the study was to determine if KS influenced the lower extremity kinematics when females with previous anterior cruciate ligament (ACL)-reconstruction and healthy participants completed an end-range squat. Study Design: A repeated measures, counter-balanced laboratory study design was used. Methods: Twenty female participants (mean (SD) – age: 21.65 (2.06) yrs, height: 175.26 (9.29) cm, weight: 64.66 (7.72) kg) with a history of ACL-repair (n=10) or non-injury (n=10) completed this study. Participants completed a standardized trial of three deep squats with and without KS. Movement was analyzed using 2D video analysis methods increasingly available in clinical environments. Results: During the ascending phases of a squatting motion, there was significantly greater medial (p = .009) and lateral (p = .005) motion of the patella in the frontal plane for non-injured participants, when compared to the ACL-repaired group. No significant differences were found in sagittal plane lower extremity kinematics when squatting with and without KS. Ascending angular velocity was slower in ACL-repaired than non-injured females (p = .008) and slower with the KS than without KS for non-injured females (p = .007). Conclusions: When squatting with and without KS, the non-injured group experienced more frontal plane motion at the knee, compared to the ACL-repaired group. However, while KS are purported to influence lower extremity joint positions during the bottom phase of a deep squat, the data from the current study did not support this claim. Additionally, KS appear to slow ascending velocity for those without a history of ACL-repair. These findings may have clinically meaningful implications for athletes who use KS during sport activities. Level of Evidence: Level 2 Key words: Functional movement assessment, Knee Savers®, softball, varus, valgus

1

Department of Nutrition and Kinesiology, University of Central Missouri, Warrensburg, MO, USA 2 School of Kinesiology, Recreation and Sport, Western Kentucky University, Bowling Green, KY, USA 3 Department of Physical Therapy, Western Michigan University, Kalamazoo, IN, USA This study was approved by the university’s institutional review board and an approved informed consent form was signed by each of the participants prior to testing. There were no sources for grant support.

CORRESPONDING AUTHOR Donald Hoover Department of Physical Therapy, Western Michigan University, Kalamazoo, MI, 49008 E-mail: don.hoover.pt.phd@gmail.com

The International Journal of Sports Physical Therapy | Volume 12, Number 5 | October 2017 | Page 737 DOI: 10.16603/ijspt20170737

INTRODUCTION Prolonged squatting by baseball and softball catchers is widely believed to be detrimental to the knees of these athletes. Although not universally defined, a decreased risk of knee injury when deep squatting may be promoted through the use of ergonomic aids.1 Knee Savers® (KS) have been advertised as an ergonomic aid purported to reduce knee loading during squatting as well as decrease undesirable movement patterns [e.g., excessive forward trunk lean, anterior knee translation past the toes, greater degrees of peak knee flexion, etc].1 Anecdotally, KS are widely used by both softball and baseball catchers, and users report subjectively that KS change lower extremity position, improve balance, and lessen fatigue while playing the catcher position in these sports. To describe KS more fully, they are dense foam pads used as an ergonomic aid to reduce the loading placed on the knee.1 Athletes wear KS by strapping them over the belly of the calves, providing a wedge between the calves and posterior thighs when in a deep squat position. Some authors have posited that during a sustained deep squat, the connective tissues within the lower extremity may be exposed to creep phenomenon, thereby plausibly contributing to increased joint laxity in the lower extremities.2 Proponents of KS suggest that these ergonomic aids lessen the tensile load on the connective tissues within the knees’ ligaments and joint capsule,1 based on the premise that these pads limit end-range motion and thus prevent “bottoming out” during a deep squat. In turn, some authors suggest that females may be at some degree of greater risk of creep phenomenon during sustained deep squatting due to the effects of hormonal fluctuations associated with the menstrual cycle, with associated effects upon joint connective tissue laxity.3 Nonetheless, while KS are used widely by softball and baseball catchers, a review of the Medline, CINHAHL, and SportDiscus electronic databases suggests that no known empirical evidence exists to support the claim that this aid prevents the endrange lower extremity kinematics used in dynamic deep squatting, squatting to end range and rapidly standing, that some believe may increase the risk of knee injury.1 Additionally, the effects of these ergonomic aids on performance are not well understood.

Acknowledging that 20% of injuries in females who play softball occur as knee and ankle ligament derangements,4 evaluating lower extremity kinematics during deep squatting is clearly relevant to the topic of knee injuries, their prevention, and their rehabilitation. Serious knee injuries, such as rupture of the anterior cruciate ligament (ACL) are a risk for many athletes,5 with females four to six times more likely to sustain ACL injuries compared to their male counterparts.6 Recent research links lower extremity valgus postures during squatting tasks, and the associated risk of ACL injuries, to poor neuromuscular coordination patterns of the trunk and lower extremities.6 As a consequence of such research, it is now common for sports physical therapists to screen individuals for dynamic lower extremity postures during functional movements such as squats or step downs.7,8 Similarly, after an ACL injury, full functional return to squats or other movements can be an elusive outcome, even with successful surgical repair.9 While researchers have quantified differences in lower extremity kinematics when comparing ACL-repaired females with non-injured controls,10 authors have also noted that both populations are likely to demonstrate quadriceps-dominant and other dysfunctional movement strategies that can challenge the integrity of the knee’s static stabilizing structures.6 Such movement strategies frequently seen in females tend to subject the ACL to high tensile loads and thus increase its risk of rupture by six fold or rerupture by four fold.11 In summary, anecdotal evidence suggests that sports physical therapists are increasingly aware of the scientific literature on the negative impact of lower extremity movement dysfunction on knee health. Anecdotal evidence also suggests that sports physical therapists increasingly include screens for dysfunctional movement patterns in their patient examinations. However, while this approach should be commended, it is not without its drawbacks given the widespread reliance by clinicians in the field upon visual-only qualitative motion analysis (VOQMA). Identifying undesirable movement patterns – particularly during high velocity activities can be challenging for even experienced clinicians given the limitations of VOQMA. Consequently,

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given the contemporary digital revolution, larger numbers of physical therapists are moving away from relying solely on VOQMA by incorporating 2-D motion analysis software applications that are increasingly available. In this context, researchers can help to bridge the “theory-practice-gap” longnoted in the kinesiology literature12 by conducting studies using methods which clinicians more commonly have at their disposal. In short, the use of such software applications, might reasonably provide practitioners with additional means of evaluating the subtle impact ergonomic aids, such as KS, may have upon movement patterns of the body.

participants included the ability to squat to the point where the posterior thighs were in contact with the calves while maintaining one’s balance on the toes, as well as the capacity to squat ten times without acute pain in the lower extremities. The study protocol was approved by the Institutional Review Board at Western Kentucky University. All data collection occurred in the Human Performance Laboratory within the Doctor of Physical Therapy Program. Prior to testing, all participants completed written informed consent. Demographic data for the participants are shared in Table 1.

Thus, the purpose of the study was to determine if KS influenced the lower extremity kinematics when females with previous anterior cruciate ligament (ACL)-reconstruction and healthy participants completed an end-range squat. A third goal of this study was to use digital video technology, increasingly used in sports physical therapy environments, to assess lower extremity kinematics. It was hypothesized that there would be measurable differences in lower extremity kinematics when squatting with and without KS and between ACL-repaired and noninjured females.

Procedures The procedures were completed as a laboratory-controlled, repeated measures design. Upon arrival for participation, individuals were briefed on the study and then completed the informed consent document. The participants were grouped into either the ACL-repaired (n=10) or non-injured group (n=10). Participants’ body mass and height were collected using standardized procedures using a digital scale and stadiometer (Table 1). Participants were then instructed to change into standardized testing attire, which consisted of black long-sleeve shirts and tights. Reflective tape (1x1 inch) was affixed to the following bony landmarks; bilaterally on the acromioclavicular joint, anterior superior iliac spine, and the center of the patellae, as well as unilaterally to the left lateral femoral condyle, lateral malleolus, and greater trochanter. The reflective tape was placed on top of the tights, over each bony landmark noted above, and remained in the appropriate position during the movement.

METHODS Participants A quasi-experimental design was used to assess the effects of KS on kinematic measures in the lower extremities during a dynamic squat. A sample of convenience consisting of twenty (n =20) females (mean (SD) – age: 21.65 (2.06) yr, height: 175.26 (9.29) cm, weight: 64.66 (7.72) kg) participated in this study. Ten of the participants reported a history of ACL-repair, while the other ten participants reported no current pain or history of injury to the lower extremities or torso. Inclusion criteria for all

Once markers were placed, the participant began a standardized warm up of treadmill walking and deep squats. Prior to each condition, participants received a minimum of three practice trials by squatting to the

Table 1. Descriptives of the participants (females, N = 20)

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greatest self-selected depth allowed while remaining balanced on the toes; these depths were not equalized to make the findings more generalizable to actual performance. The participants remained in the squat for seven seconds, then the investigator gave a count down by speaking, “3, 2, 1, up”. The participant then ascended to the standing position as quickly as possible. The three data collection trials were conducted the same as practice trials. After performing each trial, the participant rested for 15-20 seconds before each subsequent trial. The mean values for all three trials were considered in the data analyses. Squatting without KS served as the control (CON) condition, and squatting with KS was the experimental (EXP) condition, with conditions counterbalanced to prevent testing order effects. These conditions are depicted in Figure 1. During the EXP condition, participants squatted with the KS affixed on the posterior portion of the lower extremity, following manufacturer instructions. The use of the KS in this study was standardized by affixing these pads

in the standing position, so that the top of the KS pad was positioned 5.08 cm (2 in) below the popliteal crease. The pair of KS used in this study was new, selected on the basis of minimizing the effect that the typical material fatigue or “wear and tear” of a used pair of KS might have on the fit and function during use. Dynamic squatting performance was captured using digital video cameras with a sampling rate of 30 Hz (Panasonic PV-GS300, Secaucus, NJ, USA), as these are technical specifications widely available to individuals who film in clinical environments. One digital video camera was positioned to assess motion in the frontal plane; the other digital video camera was positioned to collect sagittal plane motion. The cameras were stationed so that the participants’ entire body was in view during the ascent and decent portions of the squat. Markers of known distance were placed horizontally and vertically around the participant to standardize distances for ad hoc

Figure 1. Sagittal plane views of no-KS and KS conditions in standing and squatting positions. The views are as follows: 1) No-KS, Standing; 2) No-KS, Squatting, 3) KS, Standing; 4) KS, Squatting. The International Journal of Sports Physical Therapy | Volume 12, Number 5 | October 2017 | Page 740

measurements. Moreover, the cameras were not moved during data collection to ensure reliability of measurements. Marker positions were digitized using Dartfish 7© software (Dartfish USA, Atlanta, GA, USA). Researchers have found Dartfish© a valid and reliable 2D kinematic analysis instrument for both static and dynamic evaluations.13 Variables assessed in the frontal plane were horizontal displacements of the right and left legs, tracked as the individuals descended into and ascended out of a deep squat. The descent phase began with the participant standing upright and ended at the lowest position of the squat. The ascent phase began at the lowest position of the squat and ended when the participant was standing upright. Patellar motion in the frontal plane was defined as horizontal displacement of the patella away/toward the body’s midline (i.e., lateral motion-varus, medial motion-valgus), using the previously described methods.8 A vertical line was added in Dartfish, equidistant to the anterior superior iliac spine markers, to represent the body’s midline. The tracking tool in Dartfish measured the distance each patella traveled away/ towards the established midline. All patellar motion deviation scores were standardized to body height and are reported in cm/m. Variables assessed in the sagittal plane included angular kinematic variables and anterior translation of the patella past the toes. Angle measures were made by visually identifying frames at the bottom phase of the squat, prior to ascent. Analysis of hip and knee flexion angles and absolute shank angle (horizontal reference) were assessed using the angle calculation tool in Dartfish©. The hip flexion angle was defined using the markers on the left acromioclavicular joint, left greater trochanter, and left femoral condyle. The knee flexion angle was defined using the markers on the left greater trochanter, left femoral condyle, and lateral malleolus. The absolute shank angle was comprised of the vertex of a line running through the left femoral condyle and lateral malleolus markers and a horizontal axis running through the left lateral malleolus. Anterior translation of the patella past the toes was assessed immediately prior to ascent by measuring the horizontal distance from the patella marker to the toe marker. Instantaneous knee angular velocities were calcu-

lated during the entire ascent phase using the finite difference technique.14 The average value of these instantaneous calculations was reported as the average knee angular velocity during the ascent phase. The peak knee angular velocity was the maximum angular velocity occurring during the ascent phase. STATISTICAL METHODS Statistical analysis was conducted using SPSS 24.0 (IBM SPSS, Armonk, NY, USA). Descriptive statistics were calculated for study variables. A familywise alpha of 0.05 was predetermined to denote statistical differences. An analysis of variance (ANOVA) with repeated measures to compare group interactions (Groups x KS x Limb) was used to evaluate frontal plane kinematics. The effect of KS and limb (within) were compared using main effects outcomes along with an evaluation between ACL-repaired and non-injured groups. A repeated measures ANOVA was utilized to quantify the effect of KS on standing angular velocity (within) and angular velocity between groups. Follow up analyses for each ANOVA utilized Bonferroni post hoc corrections. The magnitude of effect between groups and within conditions were calculated and expressed as effect sizes. Some data points were omitted from the angular velocity analysis due to visual interference from the upper extremity with the knee marker. However, missing data points occurred early in the ascent phase of the squat and would not have reflected peak standing angular velocities. Additionally, the proportion of participants missing data were equal across the ACLinjured and non-injured groups. RESULTS Descriptive statistics for each repeated measures ANOVA are available in Table 2. A repeated measures ANOVA was used to evaluate frontal plane kinematics based on the KS condition, limb tested, and injury designation (ACL-repaired vs non-injured females). The interaction between the predictors in the model and lateral deviations, Wilks F(1,13) = 0.96, p = .34, ηp2 = 0.07 and medial deviations, Wilks F(1,13) = 0.93, p = .36, ηp2 = .07 was non-significant. Simple effect Welch ANOVAs (αfw = .05) were conducted to compare the peak medial and lateral knee deviations during the descent phase of a terminal squat between groups (ACL-injured vs non-injured).

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Table 2. Descriptive statistics and outcome data for repeated measures ANOVAs.

Pairwise comparisons indicated that ACL-repaired females experienced less lateral deviation of the knee in the frontal plane when compared to noninjured females, F(1,13) = 6.36, p = .026, ηp2 = 0.33 (Figure 1). When evaluating pairwise comparisons, medial deviations were significantly higher in the non-injured females, compared to ACL-repaired females, F(1,13) = 34.27, p = .022, ηp2 = 0.34 (Figure 2). There were no differences in medial or lateral deviation scores between the EXP and CON conditions or limbs during the descent phase. Peak lateral and medial deviations at the knee during the ascent phase of squatting were evaluated using simple effect Welch ANOVAs where condition (EXP vs CON) and limb were within variables and group was the between factor. Peak lateral knee deviations were higher in the EXP condition compared to the CON condition, Wilks F(1,17) = 10.27, p = .005, ηp2 = .38 (Table 2). There was no difference in ascent lateral deviation between groups or

limbs. Peak medial knee deviations during ascent did not differ between limbs or groups, but were greater in the EXP condition compared to the CON condition, Wilks F(1,17) = 8.69, p = .009, ηp2 = .39. A repeated measures ANOVA was used to compare limb angles and positions in the bottom phase of

Figure 2. Frontal plane knee kinematics in the ascending and descending phases of a deep squat. * = p < .05.

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a squat and ascending angular velocities between experimental conditions and groups. Terminal knee angle, hip angle, absolute shank angle and distance travelled by the knee past the toes did not differ for participants regardless of experimental condition or group. While not representative of all participants, and across conditions, the average knee angle (recorded as the angle below the parallel squat position) was 38.1 ± 8.0 degrees and 42.3 ± 6.0 degrees, and the distance the patella travelled past the toes was 11.3 ± 4.2 cm/m and 13.1 ± 1.8 cm/m for noninjured and ACL-repaired females, respectively. Pairwise comparisons indicated that ascent average angular velocities were not significantly different between groups, but were slower in the EXP condition compared to the CON condition, Wilks F(1,18) = 9.16, p = .007, ηp2 = .34. A main effect for condition was noted for ascent peak angular velocities, Wilks F(1, 18) = 5.36, p = .033, ηp2 = 0.23. Additionally, there was a condition by group (KS x Group) interaction, Wilks F(1,18) = 4.731, p = .043, ηp2 = .21. Follow up analyses to the significant interaction indicated slower peak angular velocities in the ACLrepaired group compared to the non-injured group (Figure 2), F(1,18) = 8.77, p = .008, ηp2 = .33. The main effect for EXP condition revealed a significant difference for peak ascending angular velocity, Wilks F(1,18) = 5.36, p = .033, ηp2 = .23. DISCUSSION The present study set forth to determine if KS changed frontal plane and/or sagittal plane lower extremity kinematics when performing a dynamic deep squat or elicited any measurable differences in the lower extremity motion of ACL-repaired and non-injured females. There were three major findings from the current study: 1) Abnormal frontal plane knee kinematics were more pronounced in the non-injured compared to the ACL-injured females; 2) Females with a history of ACL reconstruction had slower standing knee angular velocity than their non-injured counterparts; 3) The addition of KS negatively affected ascending knee angular velocity for all females. When compared to non-injured controls, females with a history of ACL-injury demonstrated significantly less medial and lateral translation of the knee when descending and ascending from a squat.

This finding is consistent with many reports that females, in general, frequently demonstrate deficiencies in neuromuscular coordination patterns during the eccentric phase of many closed kinetic chain activities.15 As explained by Hewett et al,6 females are much more likely to demonstrate asymmetrical lower extremity movement patterns, or one-leg dominance, than are their male counterparts. Therefore, the data from this study suggest that the non-injured group may have adopted a leg dominance approach when descending into a deep squat. Due to past traumas, the lower magnitude of medial and lateral deviation demonstrated by the ACL group may be attributed to heightened proprioception of the lower extremity, plausibly gained through rehabilitation.16 Further, there is evidence that trauma to the ligament will result in modified motor programs.17 Through physical therapy, the ACL participants may have refined motor programs to better recruit motor units bilaterally,18 whereas the non-injured group may not have attuned these neural pathways. Yet, as information on muscle strength, leg dominance, and muscle recruitment patterns were not collected within this study, it may be surmised from the difference between groups that the non-injured group may have adopted the reported “leg dominant” approach during both phases of squatting, compared to the ACL-repaired group. However, this observation is speculative in lieu of further study that includes such information. Still, sports medicine professionals should be mindful of lower extremity movement asymmetry and evaluate each female participant individually for unilateral strength disparities. On the basis of altering somatosensory input to the central nervous system alone, it may be hypothesized that adding a foreign object to an individual’s lower extremities when in a full squat position may alter inherent postural control strategies and thus change lower extremity kinematics (e.g. hip, knee, ankle flexion angles). However, based on the present findings, it appears that KS did not significantly alter lower extremity kinematics when deep squatting. It was anticipated that the addition of KS would affect the measures of knee and hip flexion, absolute angle of the shank, and distance the knees translated past the toes. With the present findings, the authors rejected the primary hypothesis that KS

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would change squatting mechanics when compared to squatting without KS. Related to this notion, analyses were conducted to determine if there were differences for static kinematic measurements between participants when squatting with and without KS. The results also indicated that no significant differences in kinematics existed between the ACL-repaired and non-injured groups. Supporting the presenting findings, researchers have found no differences in postural control between ACL-injured vs non-injured groups when evaluating a dynamic balancing task.19 However, literature has also shown a significantly diminished ability of ACL-repaired participants to maintain center of pressure during a dynamic balancing task compared to healthy controls.20 The lack of variability between groups in the present study may be because KS are minimally invasive to the athlete’s postural control. Future studies may evaluate ergonomic wedges that provide greater support and less knee flexion in order to delineate differences in postural control when squatting with and without the aid. The results of the current study are limited as specific lower extremity kinematics were assessed at a single time point during squat performance. Additionally, postural variability throughout the squat cannot be determined, as forces were not measured in the present study.

the KS condition and 2) KS slow the time needed for all females to stand from a full squat. While it is understood by the investigators that athletes playing the catcher position rarely need to come to a fully erect position prior to completing a play, this initial study demonstrates a dramatic difference in ascending knee angular velocity when KS are present or not. While not assessed directly in this initial study, the investigators postulate that this change in ascending velocity might originate from altered somatosensory input due to greater tibial-femoral separation. The latter speculation is a derivative of no change in hip, knee, or ankle joint angles when KS were present or absent. Being that an inorganic object was wedged between the tibia and femur with no postural repercussions suggests that the knee joint itself absorbed the additional space needed to accommodate the KS. With that, two theories may be speculated: 1) greater separation between the tibia and femur could have created added strain on both contractile and non-contractile units needed to maximally accelerate or 2) the presence of the foam wedge elicited a relaxation state, consequently delaying the activation of musculature necessary to ascend rapidly from a terminal squat position. However, future investigations are necessary to support or refute either claim.

No differences were found between KS and no KS in the postural or kinematic variables. Therefore, it may be posited that there are no differences in multi-joint muscle recruitment synergies when stabilizing in the bottom phase of a deep squat between these conditions. However, future study is necessary before drawing such a conclusion. Although not investigated, KS may have instead caused changes in other biomechanical factors, such as joint torque and muscle activation patterns. Additionally, KS appear to neither help nor hinder position of the knee relative to the foot. Although KS are suggested to benefit the knee joint while squatting, while speculative, the present data would suggest there is no difference when squatting with or without KS in regards to sagittal plane kinematics. Future investigation may elucidate this postulation.

These findings also suggest that statistically significant differences in lower extremity frontal plane motions may be detected using technology widely available to clinicians. Thus, the findings of the present study have clinical meaningfulness in helping rehabilitation professionals bridge the gap between measurement methods used in laboratory conditions and those widely used in the field. Finally, given the ease of use of the DartfishŠ software employed in this study, the present findings suggest motion analysis software may be a reasonably easy tool for rehabilitation professionals to embrace as an adjunct to the VOQMA that predominates in clinical environments.

Related to performance, the data suggest: 1) Females with a history of ACL-repair return to standing at slower velocities than non-injured females despite

Limitations of the study include using a sample of convenience to recruit individuals possessing apparently healthy and ALC-repaired status, not controlling for time since ACL repair, lack of data smoothing, analyzing data through instantaneous calculations from video in DartfishŠ, and the inability to provide

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quantitative measurement of varus or valgus angles with the 2D videography analysis system; however, it should be noted that there are high correlations between 2D and 3D videography when evaluating dynamic valgus motions.21 Future research on this topic might also likely include participants with experience as catchers in softball, as well as include modified stance(s) to more closely replicate game situations and thus improve the generalizability of such studies to application during sporting activity. CONCLUSION Knee Savers® do not appear to elicit a change in frontal plane lower extremity kinematics when ascending from a deep squat, and provide no significant change in sagittal plane static variables at the bottom of a deep squat. However, the addition of KS slowed the average ascending knee angular velocity across both groups. A history of ACL-repair does not appear to negatively affect knee motion with, or without, these devices. However, these findings support previous studies showing that non-injured females often demonstrate poor lower extremity kinematics associated with increased risk of ACL injury. Lastly, these findings suggest the Dartfish© platform may allow sport professionals to help detect clinically meaningful measures – such as abnormal frontal plane motion – when working in the field.13,20 REFERENCES 1. Farrago DM, M FD. Patent US5073986 - pad structure for relieving knee stress. Google Books; August 2, 1990. https://www.google.com/patents/US5073986. Accessed October 23, 2016. 2. Ryan ED, Herda TJ, Costa PB, et al. Dynamics of viscoelastic creep during repeated stretches. Scand J Med Sci Sports. 2011;22(2):179–184. 3. Renstrom P, Ljungqvist A, Arendt E, et al. Noncontact ACL injuries in female athletes: An international Olympic committee current concepts statement. Br J Sports Med. 2008;42(6):394–412. 4. Marshall S, Hamstra-Wright K, Dick, R, et al. Descriptive epidemiology of collegiate women’s softball injuries: National collegiate athletic association injury surveillance system, 1988-1989 through 2003-2004. J Athl Train. 2008;42(2):286-294. 5. Gilchrist J, Mandelbaum BR, Melancon H, et al. A randomized controlled trial to prevent noncontact anterior cruciate ligament injury in female collegiate soccer players. Am J Sports Med. 2008;36:1476-1483.

6. Hewett TE, Ford KR, Hoogenboom BJ, et al. Understanding and preventing acl injuries: Current biomechanical and epidemiologic considerations update 2010. N Am J Sports Phys Ther, 2010;5:234-251. 7. Wilson J, Ireland M, Davis I. (2006). Core strength and lower extremity alignment during single leg squats. Med Sci Sports Exerc. 2006;38(5):945-952. 8. Shirey M, Hurlbutt M, Johansen N, et al. The influence of core musculature engagement on hip and knee kinematics in women during a single leg squat. Int J Sports Phys Ther, 2012;7:1-12. 9. Villadsen A, Overgaard S, Holsgaard-Larsen A, et al. Postoperative effects of neuromuscular exercise prior to hip or knee arthroplasty- A randomized control trial. Osteoarthritis Cartilage. 2013;21:S53. 10. Hewett TE, Myer GD, Ford KR, et al. Biomechanical measures of neuromuscular control and valgus loading of the knee predict anterior cruciate ligament injury risk in female athletes: A prospective study. Am J Sports Med. 2005;33:492-501. 11. Paterno M, Raugh M, Schmitt L, et al. Incidence of contralateral and ipsilateral anterior cruciate ligament (ACL) injury after primary ACL reconstruction and return to sport. Clin J Sport Med. 2012;22(2):116-121. 12. Knudson D. Evidence-based practice in kinesiology: Theory to practice gap revisited. Physical Educator. 2005;62:212-221. 13. Mier CM. (2011). Accuracy and feasibility of video analysis for assessing hamstring flexibility and validity of the sit-and-reach test. Res Q Exerc Sport. 2011;82:617-623. 14. Winter DA. Biomechanics and motor control of human movement. 4th ed. Hoboken, NJ: John Wiley & Sons. 2009;45:81 15. Salem GJ, Salinas R, Harding FV. Bilateral kinematic and kinetic analysis of the squat exercise after anterior cruciate ligament reconstruction. Arch Phys Med Rehabil. 2003;84:1211-1216. 16. Wilk KE, Arrigo C, Andrews JR, et al. Rehabilitation after anterior cruciate ligament reconstruction in the female athlete. J Athl Training. 1999;34(2):177-193. 17. Johansson H, Sjolander P, Sojka P. Receptors in the knee joint ligaments and their role in the biomechanics of the joint. Crit Rev Biomed Eng. 1991;18:341-368. 18. Mulder T, Hulstyn W. Sensory feedback therapy and theoretical knowledge of motor control and learning. Am J Phys Med. 1984;63:226-244. 19. Goetschius J, Kuenze CM, Saliba S, et al. (2013). Reposition acuity and postural control after exercise in anterior cruciate ligament reconstructed knees. Med Sci Sports Exerc. 2013;45(12):2314-2321.

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20. Davids K, Kingsbury D, George K, et al. Interacting Constraints and the Emergence of Postural Behavior in ACL-DeďŹ cient Subjects. J Motor Behav. 1999;31(4):358-366.

21. McLean SG, Walker K, Ford KR, et al. (2005). Evaluation of a two dimensional analysis method as a screening and evaluation tool for anterior cruciate ligament injury. Br J Sports Med. 2005;39:355-362.

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IJSPT

ORIGINAL RESEARCH

COMPARISON OF DRY NEEDLING VS. SHAM ON THE PERFORMANCE OF VERTICAL JUMP William D Bandy, PT, PhD, SCS1 Russell Nelson, PT, PhD, SCS, ATC2 Lisa Beamer, PT, DPT2

ABSTRACT Introduction: Dry needling has been reported to decrease pain in subjects having myofascial trigger points, as well as pain in muscle and connective tissue. Objective: The purpose of the study was to compare the effects on the ability to perform a two-legged vertical jump between a group who received one bout of dry needling and a group who received one bout of a sham treatment. Methods: Thirty-five healthy students (19 males, 16 females) were recruited to participate in this study (mean age 22.7+/- 2.4 years). The subjects were randomly divided into two groups- dry needling (n=18) vs sham (n=17). The dry needling group received needling to four sites on bilateral gastrocnemius muscles; two at the medial head and two at the lateral head. The sham group had the four areas of the gastrocnemius muscle pressed with the tube housing the needle, but the needle was never inserted into the skin. Two-legged vertical jump was measured with chalk marks on the wall before and after the dry needling and sham treatments. Results: Analysis with a t-test indicated that the dry needling group significantly increased vertical jump height 1.2 inches over the sham group. Conclusion: One bout of dry needling showed an immediate effect at significantly increasing vertical jump height in healthy, young adults. Future research is needed to determine if dry needling has any longterm effects. Level of Evidence: 2b Key Words: dry needling, trigger points, vertical jump

1 2

University of Central Arkansas, Conway, AR, USA Christus St. Michael Hospital, Texarkana, AR, USA

Acknowledgements The authors wish to thank Hannah Nelson, Halah Nelson, and Melissa Carter for their assistance with data collections.

CORRESPONDING AUTHOR William D Bandy, PT, PhD, SCS Department of Physical Therapy University of Central Arkansas Conway, AR E-mail: billb@uca.edu

The International Journal of Sports Physical Therapy | Volume 12, Number 5 | October 2017 | Page 747 DOI: 10.16603/ijspt20170747

INTRODUCTION The American Physical Therapy Association describes dry needling as a skilled intervention performed by a physical therapist that uses a thin filiform needle to penetrate the skin and stimulate underlying myofascial trigger points as well as muscle and connective tissue.1 Dry needling is used to manage neuromuscular impairments, and treat pain associated with trigger points. Tekin et al2 reported dry needling to be effective in relieving pain and improving quality of life of subjects suffering from myofascial pain syndrome. Llamas3 reported dry needling to be as effective in increasing cervical range of motion and decreasing pain as manual therapy. This particular study3 also found dry needling to be more effective in improving pressure pain thresholds or decreasing pain sensitivity in patients. A similar study determined that a single session of dry needling decreased neck pain and increased cervical range of motion.4 Dry needling has been found to be effective for up to six weeks in reducing the symptoms in subjects suffering from fibromyalgia.5 Dry needling combined with physical therapy has been found to reduce pain and increase range of motion and function in subjects suffering from chronic pain following a total knee arthroplasty.6 Haser et al7 investigated the treatment of chronic ankle sprains in soccer players and found dry needling to be an effective adjunct to proprioceptive and strengthening exercises for the management of chronic ankle sprains. In addition, Haser et al7 reported that dry needling increased maximal force output of the quadriceps muscles and decreased injuries. Lavelle et al8 reported that dry needling releases opioid peptides, creating an environment for tissue regeneration and reducing the concentration of nociceptive and reducing the level of nociceptive and sensitive chemical substances in the immediate environment around the trigger point. Myofascial trigger points (MTrPs) are localized hypersensitive spots in a tight band of muscle.9 The MTrP, often undiagnosed, are very often found in subjects suffering from myofascial pain.10 These MTrPs can be active or latent, with active MTrPs being the most common trigger points treated in the clinic.10 While MTrPs cause spontaneous pain and are painful upon palpation of that area, latent trigger points do not produce spontaneous pain but are only painful to palpation.10 These latent trigger points

have proven to cause accelerated muscle fatigue and overload of non-affected motor units near the trigger point.11 Quinn et al12 compared the use of myofascial trigger point therapy and medicine ball exercises to no intervention on hip flexor length, golf swing biomechanics, and performance in elite golfers. The authors found that backswing hip turn improved in the group receiving myofascial trigger point therapy and medicine ball exercises.12 The purpose of the study was to compare the effects on the ability to perform a two-legged vertical jump between a group who received one bout of dry needling and a group who received one bout of a sham treatment. Vertical Jump is often used as an indicator of an measurement of lower extremity power.13,14 Training programs have used the vertical jump as an indicator as to whether or not the program adequately improves athletic performance.13,14 METHODS Thirty-five healthy asymptomatic college students signed an informed consent form. Subjects with any lower extremity injuries within the prior year were excluded. The protocol and procedures were approved by the Institutional Review Board at the University of Central Arkansas. Subjects were randomly assigned to the sham group or to the dry needling group. The subjects were blinded to which group they were assigned. PROCEDURES Once each participant signed the informed consent, he or she performed a two-minute warm-up. The warm-up consisted of jogging in place. After finishing the warm-up, the subject dipped their finger in ground up chalk. The chalk was used to mark the wall during the performance of the vertical jumps. The subject first reached as high as he or she could and touched the wall leaving a chalk mark. The subject then jumped off two feet as high as he or she could and touched the wall leaving another chalk mark. The subjects were allowed to use arms for counter movement swing. The distance between the two marks were then measured and recorded as vertical jump height. The gastrocnemius muscles of all subjects participating in the study were then palpated to determine if

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Once the subject finished the dry needling or sham portion of the study, he or she was asked to perform another vertical jump, in the same manner as the first attempt. The time between the first jump - and then being randomly assigned to a group and receiving the dry needling or the sham treatment – was an average of 10 minutes until the second jump. The second jump was measured and recorded using the same procedures as the initial jump. The researcher measuring vertical jump, before and after dry needling or sham, was blinded as to whether the subject received the dry needling treatment or the sham. Data Analysis Figure 1. Procedure for intervention in dry needling group.

trigger points were present. If no true (active) trigger points were found, areas of tightness were palpated and considered to be a latent trigger point. The subject’s calves were then wiped with alcohol to prevent possible infections. All subjects received needling with four needles in each leg. After palpation, two areas in the medial head of the gastrocnemius and two areas of the lateral head of the gastrocnemius of both legs received dry needling (Figure 1). The tube was placed on the skin and the needle was tapped and inserted; no pistoning was performed. At four points on each leg, the needles were inserted, one right after the other, resulting in almost simultaneous insertion of the needles. The participants in the sham group had four areas of the gastrocnemius muscle of both legs pressed with the tube housing the needle after palpation, but the needle was never inserted into the skin in any of the areas. The author performing the dry needling was certified and had 3.5 years of experience performing dry needling.

The results of the sham group were used in an analysis of pre-test-post-test reliability by calculating an ICC. The difference in the first and second jump was calculated for each subject. The difference score was used to compare the dry needling group to the sham group using an independent t-test. RESULTS Mean age of the 35 participants was 22.7 (+/-2.4) and 19 males and 16 females participated. Eighteen volunteers were assigned to the dry needling group and 17 were randomly assigned to the sham group. Forty pieces of candy were placed into a bag. Twenty of the pieces were pink and twenty were yellow. The subject then chose a piece of candy from the bag. The subjects were given no indication as to what the candy represented. The subjects who chose the pink pieces of candy were placed in the dry needling group while the subjects who chose the yellow pieces of candy were places in the sham group. Descriptive statistics are presented in Table 1. An ICC performed on the sham group first test (17.19 inches +/- 4.69) compared to second test (17.56 inches +/-4.97) resulted in a correlation of .98.

Table 1. Descriptive Statistics.

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Comparing the difference scores between the dry needling group and the sham group demonstrated a significant difference (t=2.16, df=33, p=.038) of 1.2 inches. DISCUSSION The dry needling group had a significant increase in vertical jump height compared with the sham group. One of the purposes of this study was to determine if dry needling would inhibit athletic performance. The results of the current study indicate that not only does dry needling not inhibit athletic performance, but may actually enhance the performance (vertical jump). The findings of this current study indicate that the use of this treatment just prior to competition will not negatively affect performance. While the 1.2 inch increase in vertical jump was significant, the question may arise whether or not this difference is clinically relevant. A one inch increase may not make a significant difference in activities of non-athletes, but a one inch change in vertical jump in athletes may mean the difference between winning and losing. Haser et al7 found that dry needling increased maximal force in knee extensor muscles, but this current study is the first to examine the effects that dry needling has on a functional activity such as vertical jump. Vertical jump is a functional activity that can be conducted as a proxy measure of the gastrocnemius/soleus muscle complex performance.14 The findings in this study seem to concur with the results of the study by Haser et al7 who found an increase in maximal force of knee extensor muscles after dry needling. The subjects in this current study were healthy college students. Because the subjects reported no pain at any of the palpable trigger points, such points would be considered latent trigger points. According to Ge et al,15 a latent trigger point is associated with an accelerated development of muscle fatigue, while simultaneously overloading active motor units close to a myofascial trigger point. The authors15 also stated that elimination of latent trigger points may effectively reduce accelerated muscle fatigue and prevent overload within the muscle. Theoretically by releasing the latent trigger point points that may cause muscular weakness and fatigue, the subjects

increased their vertical jump significantly compared to the sham group. In the study by Haser et al,7 the participants received dry needling once a week for four weeks. This is the first study to show improvement in lower extremity function with only one bout of trigger point dry needling. Future research is needed to determine how long the effects of the one bout will last, and if the effects carry over to other sport specific activities. Future research should also focus on determining if similar effects will be seen in upper extremity activities. CONCLUSION One bout of dry needling showed an immediate effect with a significant increase in vertical jump height in healthy, young adults. Future research is needed to determine if dry needling has any longterm functional effects. REFERENCES 1. American Physical Therapy Association. Physical Therapists and the Performance of Dry Needling. Alexandria, VA:American Physical Therapy Association; 2012. 2. Tekin L, Akarsu S, Durmus O, et al. The effect of dry needling in the treatment of myofascial pain syndrome: a randomized double-blinded placebocontrolled trial. Clin Rheumatol.2013;32:309-315. 3. Llamas RR, Pecos-Martin D, Gallego-Izquierdo T, et al. Comparison of the short-term outcomes between trigger point dry needling and trigger point manual therapy for the management of chronic mechanical neck pain: a randomized clinical trial. J Orthop Sports Phys Ther. 2014;44:852-861. 4. Mejuto-Vazquez MJ, Salom-Moreno J, OrtegaSantiago R, et al. Short-term changes in neck pain, widespread pressure pain sensitivity, and cervical range of motion after the application of trigger point dry needling in patients with acute mechanical neck pain: a randomized clinical trial. J Orthop Sports Phys Ther. 2014;44:252-260. 5. Casanueva B, Rivas P, Rodero B, et al. Short-term improvement following dry needle stimulation of tender points in ďŹ bromyalgia. Rheumatol Int.2014;34:861-866. 6. Nunez-Cortes R, Cruz-Montecinos C, Vasquez-Rosel A, et al. Dry needling combined with physical therapy in patients with chronic postsurgical pain following total knee arthroplasty: a case series. J Orthop Sports Phys Ther. 2017;47:209-216.

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7. Haser C, Stoggl T, Kriner M, et al. Effect of dry needling on thigh muscle strength and hip exion in elite soccer players. Med Sci Sports Exerc. 2017;49:378-383. 8. Lavelle ED, Lavelle W, Smith HS. Myofascial trigger points. Anesthesiol Clin. 2007;25:841-851. 9. Simmons DG, Travell JG, Simmons LS. Travell and Simmons� myofascial pain and dysfunction: the trigger point manual. Volume 1, 2nd ed. Baltimore, MD: Williams and Wilkins; 1999. 10. Alvarez DJ, Rockwell PG, Trigger point diagnosis and management. Am Fam Physician. 2002;65:653-660. 11. Ge HY, Arendt-Neilsen L, Madeleine P. Accelerated muscle fatigability of latent myofascial trigger points in humans. Pain Med. 2012;13:957-964.

12. Quinn SL,Olivier B, Wood WA. The short-term effects of trigger point therapy, stretching and medicine ball exercises on accuracy and back swing hip turn in elite male golfers- A randomized controlled trial. Phys Ther Sport. 2016;22:16-22. 13. Chang, E, Norcross MF, Johnson ST et al. Relationships between explosive and maximal triple extensor muscle performance and vertical jump height. J Strength Cond Res. 2015;29:545-551. 14. Kollock R, Van Lunen BL, Ringleb SI et al. Measures of functional performance and their association with hip and thigh strength. J Athl Train. 2015;50:14-22. 15. Ronnestad BR, Kyamme NH, Sunde A, Raastad T. Short-term effects of strength and plyometric training on spring and jump performance in professional soccer players. J Strength Cond Res. 2008;22:773-780.

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IJSPT

ORIGINAL RESEARCH

INTER-RATER RELIABILITY OF THE SELECTIVE FUNCTIONAL MOVEMENT ASSESSMENT (SFMA) BY SFMA CERTIFIED PHYSICAL THERAPISTS WITH SIMILAR CLINICAL AND RATING EXPERIENCE Jeffery Dolbeer, PT, DSc1 John Mason, PT, DSc2 Jamie Morris, PT, DSc3 Michael Crowell, PT, DSc4 Donald Goss, PT, PhD1

ABSTRACT Background: The Selective Functional Movement Assessment (SFMA) assesses posture, muscle balance, and movement patterns in order to identify relevant musculoskeletal dysfunction in a clinical population. Purpose: The purposes of this study were to: (1) determine if raters with similar clinical experience and rating experience exhibit adequate agreement of the scoring for the SFMA during clinical use; (2) determine the reliability of the categorical scoring of the SFMA in a clinical population; (3) determine the reliability of the criterion checklist scoring of the SFMA in a clinical population; (4) compare the reliability of real-time assessment to recorded assessment. Design: Inter-rater reliability study Methods: 49 clinical subjects (20.7 years ± 1.6) were simultaneously assessed in real-time by two physical therapists and were recorded with digital video cameras in the sagittal and frontal view while they performed the fifteen component movement patterns that comprise the top-tier SFMA. The third physical therapist assessed the patterns from the video. Subjects were assessed using the SFMA categorical scoring and criterion checklist scoring tools. Results: The two live clinical raters demonstrated the greatest Cohen’s Kappa scores (10 of 15) with moderate or better interrater agreement (Kappa > 0.40) using the categorical scoring tool. The overall ICC [2,1] score indicated fair to moderate agreement between all raters for the criterion checklist scoring (ICC, SEM, p-value) (0.61, 8.23, p < 0.001). Real time clinical use was the most reliable method for using the criterion checklist scoring tool (0.72, 1.95, p=0.43). Conclusions: Using the categorical and criterion checklist tools in a clinical population to score the fifteen component fundamental movements of the SFMA demonstrated moderate or better reliability when performed clinically by certified SFMA raters. Level of Evidence: Reliability, Level 2 Key words: Dysfunction, functional movement, reliability

1

Baylor University-Keller Army Community Hospital Division Sports Physical Therapy Fellowship, West Point, NY, USA 2 Womack Army Medical Center, Fort Bragg, NC, USA 3 Brooke Army Medical Center, Fort Sam Houston, TX, USA 4 US Army Office of the Surgeon General, Falls Church, VA, USA The opinions or assertions contained herein are the private views of the authors and are not be construed as official or as reflecting the views of the US Military Academy, the US Army, or the Department of Defense.

CORRESPONDING AUTHOR Jeffery Dolbeer Keller Army Community Hospital, Arvin Sports Physical Therapy Clinic 900 Washington Road West Point, NY 10996 E-mail: jeff.dolbeer@gmail.com

The International Journal of Sports Physical Therapy | Volume 12, Number 5 | October 2017 | Page 752 DOI: 10.16603/ijspt20170752

INTRODUCTION The traditional biomedical model focuses on identification of anatomical sources of pain in order to label a condition with a specific pathoanatomic diagnosis. This approach leads providers to prioritize treatment solely to identified symptomatic anatomical structures. While the traditional model may be effective in treating symptomatic tissue, the underlying causes for symptom development, persistence, and recurrence may be overlooked. Using the traditional biomedical model, a provider may not discover an underlying impairment or functional limitation. Furthermore, the presence of pre-existing poor movement patterns or altered movement due to injury may influence the rehabilitation process for patients and athletes. The concept of regional interdependence suggests that seemingly unrelated impairments in remote anatomical regions may contribute to a patient’s primary complaint.1–3 Using a biomechanical model of the upper extremity, Holzbaur et al. demonstrated that the biomechanics of a given joint can depend on the posture and capability of adjacent joints.4 Cleland et al.,5 Fernandez-de-las-Penas et al.,6 and GonzalezIglesias et al.7 have demonstrated that interventions focused on the thoracic spine can affect cervical impairments.2 Boyles et al.,8 Mintken et al.,9 and Strunce et al.10 have demonstrated that interventions focused on the thoracic spine can alter shoulder symptoms.2 Deficits in hip strength and abnormal hip mechanics are positively correlated with knee pain in studies by Bolgla et al.,11 Finnoff et al.,12 Souza et al.,13 and Rowe et al.14 These studies provide construct validity to the concept of regional interdependence. Due to the concept of regional interdependence, movement screening and assessment tools are becoming more common as a method to predict injury risk and critically assess movement patterns. Standardized movement assessment tools may provide a systematic process to identify the best possible therapeutic and corrective treatment program for patients. The Selective Functional Movement Assessment (SFMA) is a standardized movement assessment tool intended to aid a clinician in identifying dysfunctional movement patterns. Appropriate identification of contributing impairments may help

the clinician develop targeted therapeutic/corrective interventions. The seven top-tier tests are the cervical patterns, upper extremity patterns, multisegmental flexion, multi-segmental extension, multisegmental rotation, single-leg balance, and overhead deep squat. Movements are performed bilaterally when appropriate which results in fifteen component fundamental movements for assessment. The SFMA is intended for a clinical population.20 Only one study to date addresses the reliability of this assessment tool. This study utilized three raters of varying experience and a video-recorded healthy group of 35 subjects performing the fundamental movements. The recordings were assessed initially and at least one week later by all three raters. Only one rater had attended a formal SFMA continuing education course. Substantial to almost perfect intra-rater reliability of the SFMA (kappa, % agreement) was observed for all three raters using the categorical scoring tool (rater A: 0.83, 0.91; rater B: 0.78, 0.88; and rater C: 0.72, 0.85).21 The criterion checklist scoring tool yielded intra-class correlation coefficients (ICCs) ranging from good to poor with the most experienced rater demonstrating the greatest intra-rater reliability. The least experienced rater demonstrated the least intra-rater reliability. Inter-rater reliability of the categorical tool was slight to substantial (0.41-0.61, 0.69-0.79) while the criterion checklist tool demonstrated unacceptable interrater reliability (ICC 0.43 [SEM 2.7]).21 In the literature review, no studies were found investigating the reliability of this assessment tool in a clinical population by certified medical providers. The purposes of this reliability study were to (1) determine if raters with similar clinical experience and rating experience exhibit adequate agreement of the scoring for the SFMA during clinical use; (2) determine the reliability of the categorical scoring of the SFMA in a clinical population; (3) determine the reliability of the criterion checklist scoring of the SFMA in a clinical population; (4) compare the reliability of real-time assessment to recorded assessment. METHODS Participants Subjects with a current history of axial, lower quarter or upper quarter pain of greater than two weeks

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duration were recruited via convenience sampling from a direct access physical therapy clinic. The subjects were active duty military Department of Defense beneficiaries. The sampling consisted primarily of Cadets from the United States Military Academy at West Point. Inclusion criteria were age 18-40 years, lower or upper quarter pain greater than or equal to 2 weeks, and a Visual Analogue Scale (VAS) pain rating of 40 millimeters (mm) or less at rest. Potential subjects were excluded if they had undergone a musculoskeletal surgery in the last 6 months, were currently pregnant, or were not fluent in English. All subjects provided written informed consent for study participation. A priori sample size calculation using “kappa-size” package R version 3.1.1 determined that 46 subjects would be sufficient for this study of inter-rater agreement at 80% power with alpha = 0.05. Procedures Each subject was simultaneously assessed in realtime by two physical therapists (Live Rater 1 and Live Rater 2), each with seven years overall clinical experience. At the same time, performance of the fundamental top-tier movements was recorded in the sagittal and frontal view. A different physical therapist with six years clinical experience (Video Rater 3), assessed the performance of the fundamental movements utilizing the video recordings. Subjects were not informed of the grading criteria but were provided with the same cueing for the tasks (Appendix A). The primary investigator provided a demonstration of each movement prior to performance. Raters did not discuss the scoring until all data were collected on subjects. All raters for this study attended the same SFMA continuing education course and were SFMA certified with approximately 400 hours of clinical SFMA experience. In order to obtain certification, medical providers are required to attend a SFMA Level 1 course and pass an online certification exam. Two-dimensional video was captured with Casio Exilim Digital Cameras at 30 frames/sec. Two video views (frontal and sagittal) were utilized to capture the quality of the movement performed. Cameras were placed on tripods at a height of 1.6 meters. The recordings for the cervical movements were captured at a distance of 1.3 meters and 1.0 meters for

cameras 1 and 2 respectively. The recordings for the remaining movements were captured at 2.1 meters and 1.8 meters for cameras 1 and 2 respectively (Figure 1). Videos were reviewed by Video Rater 3 using two synced playback screens in Kinovea 0.8.15 on a 65-inch LCD monitor. Each video could be viewed a maximum of two times. Scoring Subjects were scored using the SFMA Categorical Scoring tool and the SFMA Criterion Reference Scoring Checklist. The categorical scoring options are Functional Non-painful (FN), Functional Painful (FP), Dysfunctional Non-painful (DN) and Dysfunctional Painful (DP) (Appendix B). The criterion checklist scoring requires assigning an ordinal scale rating to each top-tier movement. A score of zero indicates perfect performance without compensation for all movements. A total score of 50 indicates failure of all criteria (Appendix C). Subjects were instructed to notify Live Rater 1 and Live Rater 2 if pain was present or increased during each movement. Onset of pain or increased pain presence was indicated to Video Rater 3 by the live raters raising a sign indicating pain directly in front of the cameras. Statistical Analysis The results of categorical scoring were compared between raters using percent agreement, Cohen’s Kappa coefficients, and Bennett’s Kappa coefficients to compare degree of agreement. Cohen’s Kappa coef-

Figure 1. Layout for data and video collection. m= meters

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ficients were calculated for each of the fifteen component fundamental movements between raters. Since Cohen’s Kappa can be artificially reduced with large or small prevalence of a condition,22 Bennett’s prevalence-adjusted bias-adjusted Kappa (PABAK) was used for a secondary analysis to determine the agreement on functional versus dysfunctional movement. This allows the use of 2 x 2 table analysis, which is required for PABAK calcuation.22–24 Interpretation of reliability results were based on the following criterion: Kappa > 0.80 = excellent, > 0.60 = substantial, > 0.40 = moderate, < 0.40 = poor to fair.25,26 The results of criterion checklist scoring reliability were assessed using Intra-class Correlation Coefficients (ICCs) with 95% confidence intervals (CI), Standard Error of Measurement (SEM), and Minimum Detectable Difference (MDD) calculated for the scores of each subject.26 The composite criterion checklist score and the individual inter-rater comparisons were assessed between raters (ICC [2,1]). Interpretation of reliability results were based on the following criterion: ICC > 0.90 = excellent, > 0.75 =

good, > 0.50 = moderate, and < 0.50 = poor.25,26 Cohen’s Kappa reliability analyses were performed using statistical analysis software R version 3.1.1 with Rcmdr package 2.1-1, EZR plugin 1.27, and psych package. PABAK reliability analyses were performed using Kappa Measurement of Inter-observer Agreement MultiCalc tool of MedCalc 3000.27 ICC [2,1] reliability analyses were performed using software R version 3.1.1 with Rcmdr package 2.1-1 and IRR package. RESULTS A total of 49 subjects (36 male and 13 female) met the inclusion criteria (Table 1). Seventeen of the subjects experienced pain when completing the fundamental movements. Subjects in clinic for a leg, ankle, or foot injury made up the largest proportion of subjects (Figure 2). When using the categorical scoring tool, subjects were scored as FN most frequently when performing right single-leg stance (46%), FP most frequently when performing left single-leg stance (4%), DP most frequently when performing overhead deep

Table 1. Descriptive Statistics for Subjects.

Figure 2. Number of injuries by region. The International Journal of Sports Physical Therapy | Volume 12, Number 5 | October 2017 | Page 755

squat (26%), and DN most frequently when performing right multi-segmental rotation (93%). The movement with the greatest frequency of dysfunction (regardless of pain) was right multi-segmental rotation (94%). The movement with the greatest frequency of pain (regardless of function) was overhead deep squat (26%). Five component fundamental movements were not painful for any of the subjects (Table 2). Live Rater 2 reported the fewest overall number of dysfunctional patterns followed by Live Rater 1 when using the categorical scoring tool. When using the criterion scoring checklist, Live Rater 2 reported the lowest mean score followed by Live Rater 1, and Video Rater 3 (Table 4). Inter-rater reliability of the categorical scoring tool varied between raters (Table 2). Live Rater 1 and Liver Rater 2 demonstrated the greatest number of agreements with ten of the fifteen movements displaying moderate or better reliability using Cohen’s Kappa (Table 2). Using PABAK, Live Rater 1 and Live Rater 2 demonstrated the greatest number of agreements with fourteen of the fifteen movements displaying moderate or better reliability (Table 3). Inter-rater reliability of the overall criterion checklist scoring varied between raters (Table 5). All three

raters together demonstrated fair to moderate interrater reliability (ICC, 95% CI) (0.60, 0.45-0.73) for the criterion checklist scoring. Live Rater 1 and Live Rater 2 demonstrated the best inter-rater reliability (0.72, 0.55-0.83) for the criterion checklist scoring. Live Rater 1 compared to Video Rater 3 (0.56, 0.330.73) and Live Rater 2 compared to Video Rater 3 (0.55, 0.33-0.72) demonstrated the worst inter-rater reliability for criterion checklist scoring. All interrater reliability comparisons were significantly different between raters (p < 0.001) except for Live Rater 1 to Live Rater 2 (p = 0.431). DISCUSSION This is the first study to evaluate the reliability of the SFMA with a clinical population. The authors observed that certified SFMA medical providers with similar training and clinical experience could demonstrate moderate to good agreement on both SFMA top-tier scoring scales in clinical assessment of populations with known musculoskeletal injury. In a secondary analysis, the reliability of video rating improved for the categorical scoring method when able to account for the prevalence of dysfunction. Comparisons of live rating to video rating yielded the least reliable scoring for the criterion scoring checklist method.

Table 2. Inter-rater Reliability of Categorical Scoring for Component SFMA Fundamental Movements.

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Table 3. Inter-rater Reliability for Functional versus Dysfunctional Categorical Scoring of Component SFMA Fundamental Movements.

Table 4. Criterion Checklist Scoring Values by Rater.

Table 5. Inter-rater Reliability Criterion Checklist Scoring.

The Cohen’s kappa statistic provides a chancecorrected measure of agreement for categorical data such as the categorical scoring method for the SFMA (Table 2). Live Rater 1 and Live Rater 2 demonstrated moderate or better Cohen’s Kappa agreement for ten out of fifteen fundamental movements on the categorical scoring scale. The large percent agreement and the small Cohen’s kappa scores did not appear to be in concurrence as all movements except for cervical flexion displayed a percent agreement ≥ 73%. This was due to the large prevalence

of dysfunction in the clinical subject population. To account for the prevalence of dysfunction, a secondary analysis was performed examining the agreement of functional versus dysfunctional movement using PABAK analyses. All levels of agreement improved when accounting for prevalence of dysfunction in the secondary analysis with PABAK. Live Rater 1 and Live Rater 2 demonstrated PABAK moderate agreement or better on fourteen out of fifteen component fundamental

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movements. The agreement for the remaining comparisons was similarly affected by the prevalence of dysfunction in this clinical population. This is particularly evident when comparing Live Rater 2 to Video Rater 3. The high prevalence of scored dysfunction for these two raters yielded moderate Cohen’s Kappa agreement or better in only three out of fifteen fundamental movements despite a percentage agreement ranging from 67% to 88%. The PABAK values in the secondary analysis of agreement revealed twelve of the fifteen movements for Live Rater 2 to Video Rater 3 to be in moderate or better agreement. Without accounting for the prevalence of dysfunction, only reliability of the two live raters displayed moderate or better agreement for most of the fundamental movements. When able to account for the prevalence of dysfunction in a clinical population with known musculoskeletal injury, the categorical scoring displayed improved agreement for all inter-rater comparisons. For all raters, the cervical movements generally yielded smaller Cohen’s Kappa and PABAK values compared to the remaining movements. The component fundamental movement patterns of left single-leg stance, right single-leg stance, and overhead deep squat generally yielded better agreement than other patterns with Cohen’s Kappa ranging from moderate to excellent agreement across all raters. This is consistent with Glaws et al. who also reported variable agreement of SFMA component fundamental movement patterns based on video analysis of healthy subjects.21 ICC scores are used to assess the reliability of quantitative data such as the criterion scoring checklist (Table 5). The overall ICC [2,1] score indicated fair to moderate agreement among all raters for the criterion checklist scoring (ICC, SEM, p-value) (0.60, 0.45-0.73). The most reliable method for using the criterion checklist scoring was true clinical real-time use. Live Rater 1 and Live Rater 2 demonstrated moderate agreement using the criterion checklist scoring during real-time subject assessment in clinic (0.72, 1.95, p=0.43). In addition, the live clinical raters demonstrated the smallest SEM and MDD with use of the criterion checklist scoring. Glaws et al. demonstrated poor to moderate inter-rater reliability using the criterion scoring checklist during video

analysis of healthy subjects performing the top-tier fundamental movements.21 This is consistent with the current study finding of less agreement comparing live scoring to video scoring. The current study indicated reliable use of the criterion checklist scoring can best be achieved with live rating in a clinical population with known musculoskeletal injury. Scoring the presence of dysfunction with the criterion checklist tool varied between the live raters and the video rater. Live Rater 1 and Live Rater 2 demonstrated the same median criterion checklist score and similar mean scores of 16.47 and 16.08 respectively. Video Rater 3 assessed more strictly with a mean score of 20.43 for the criterion checklist scoring. It is unknown if this discrepancy is due solely to the use of video as opposed to live clinical scoring for these raters. It is possible that further formal training is necessary to ensure all raters are scoring consistently on the criterion checklist scoring method. There are several limitations to this study. The video rater was limited to two-dimensional fields of view and was unable to move freely about the room to assess the subjects. The video rater was allowed to watch the movement videos twice but was not required to view each subject’s video the same number of times. Using two synced playback screens did not allow the use of sound for video review. This required the presence of pain to be indicated to the video rater by raising a sign designating pain. On five subjects, the video rater failed to see and/or annotate the presence of pain while scoring a subject. This may have affected the percent agreement and Cohen’s Kappa scores for the categorical scoring tool. This did not affect the criterion checklist scoring or the secondary PABAK categorical analyses as they did not account for the presence of pain. While video assessment has been used in similar reliability studies,21,28,29 use of video does limit the external validity. The SFMA is intended to be used in a real-time clinical setting. It is not intended for two-dimensional video analysis. While the categorical and criterion checklist scoring methods may be reliable for live clinical use, validation and responsiveness to change in a clinical population should be determined prior to use of the

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SFMA in clinical populations. The specific inclusion of listed criteria and a numerical score for the criterion checklist scoring method does yield potential for use as a live clinical outcome tool. Live clinical scoring did provide the smallest SEM and MDD for clinical criterion checklist scoring tool. Validation of both scoring tools for clinical use would support the clinical implementation of the SFMA. CONCLUSION The SFMA categorical and criterion scoring methods, when assessed in real-time in a clinical population, demonstrated moderate to good reliability with experienced, certified raters. Future research should focus on the validity of the SFMA in a clinical population with known musculoskeletal injury. REFERENCES 1. Wainner R, Whitman J, Cleland J, Flynn T. Regional interdependence: a musculoskeletal examination model whose time has come. J Orthop Sports Phys Ther. 2007;37(11):658-660. 2. Sueki DG, Cleland JA, Wainner RS. A regional interdependence model of musculoskeletal dysfunction: research, mechanisms, and clinical implications. J Man Manip Ther. 2013;21(2):90-102. 3. McDevitt A, Young J, Mintken P, Cleland J. Regional interdependence and manual therapy directed at the thoracic spine. J Man Manip Ther. 2015;23(3):139146. 4 Holzbaur K, Murray W, Delp S. A model of the upper extremity for simulating musculoskeletal surgery and analyzing neuromuscular control. Ann Biomed Eng. 2005;33(6):829-840. 5. Cleland JA, Childs JD, McRae M, Palmer JA, Stowell T. Immediate effects of thoracic manipulation in patients with neck pain: a randomized clinical trial. Man Ther. 2005;10(2):127-135. 6. Fernández-De-Las-Peñas C, Cleland JA, Huijbregts P, Palomeque-Del-Cerro L, González-Iglesias J. Repeated applications of thoracic spine thrust manipulation do not lead to tolerance in patients presenting with acute mechanical neck pain: a secondary analysis. J Man Manip Ther. 2009;17(3):154-162. 7. González-Iglesias J, Fernández-de-las-Peñas C, Cleland JA, Gutiérrez-Vega M del R. Thoracic spine manipulation for the management of patients with neck pain: a randomized clinical trial. J Orthop Sports Phys Ther. 2009;39(1):20-27.

8. Boyles RE, Ritland BM, Miracle BM, Barclay DM, Faul MS, Moore JH, Koppenhaver SL, Wainner RS. The short-term effects of thoracic spine thrust manipulation on patients with shoulder impingement syndrome. Man Ther. 2009;14(4):375380. 9. Mintken PE, Cleland JA, Carpenter KJ, Bieniek ML, Keirns M, Whitman JM. Some factors predict successful short-term outcomes in individuals with shoulder pain receiving cervicothoracic manipulation: a single-arm trial. Phys Ther. 2010;90(1):26-42. 10. Strunce JB, Walker MJ, Boyles RE, Young BA. The immediate effects of thoracic spine and rib manipulation on subjects with primary complaints of shoulder pain. J Man Manip Ther. 2009;17(4):230236. 11. Bolgla LA, Malone TR, Umberger BR, Uhl TL. Comparison of hip and knee strength and neuromuscular activity in subjects with and without patellofemoral pain syndrome. Int J Sports Phys Ther. 2011;6(4):285-296. 12. Finnoff JT, Hall MM, Kyle K, Krause DA, Lai J, Smith J. Hip strength and knee pain in high school runners: a prospective study. PM R. 2011;3(9):792801. doi:10.1016/j.pmrj.2011.04.007. 13. Souza RB, Powers CM. Differences in hip kinematics, muscle strength, and muscle activation between subjects with and without patellofemoral pain. J Orthop Sports Phys Ther. 2009;39(1):12-19. 14. Rowe J, Shafer L, Kelley K, West N, Dunning T, Smith R, Mattson DJ. Hip strength and knee pain in females. North Am J Sports Phys Ther NAJSPT. 2007;2(3):164-169. 15. Deyle GD, Allison SC, Matekel RL, Ryder MG, Stang JM, Gohdes DD, Hutton JP, Henderson NE, Garber MB. Physical therapy treatment effectiveness for osteoarthritis of the knee: a randomized comparison of supervised clinical exercise and manual therapy procedures versus a home exercise program. Phys Ther. 2005;85(12):1301-1317. 16. Deyle GD, Henderson NE, Matekel RL, Ryder MG, Garber MB, Allison SC. Effectiveness of manual physical therapy and exercise in osteoarthritis of the knee. A randomized, controlled trial. Ann Intern Med. 2000;132(3):173-181. 17. Childs JD, Fritz JM, Flynn TW, Irrgang JJ, Johnson KK, Majkowski GR, Delitto A. A clinical prediction rule to identify patients with low back pain most likely to benefit from spinal manipulation: a validation study. Ann Intern Med. 2004;141(12):920-928. 18. Cibulka MT, Sinacore DR, Cromer GS, Delitto A. Unilateral hip rotation range of motion asymmetry

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19.

20.

21.

22. 23.

24.

in patients with sacroiliac joint regional pain. Spine. 1998;23(9):1009-1015. Muth S, Barbe MF, Lauer R, McClure PW. The effects of thoracic spine manipulation in subjects with signs of rotator cuff tendinopathy. J Orthop Sports Phys Ther. 2012;42(12):1005-1016. Cook G, Burton L, Kiesel K, Rose G, Bryant M. Movement: functional movement systems. Aptos, California: On Target Publications; 2010. Glaws K, Juneau C, Becker L, Di Stasi S, Hewett T. Intra- and inter-rater reliability of the selective functional movement assessment (SFMA). Int J Sports Phys Ther. 2014;9(2):195-207. Byrt T, Bishop J, Carlin JB. Bias, prevalence and kappa. J Clin Epidemiol. 1993;46(5):423-429. Spitznagel EL, Helzer JE. A proposed solution to the base rate problem in the kappa statistic. Arch Gen Psychiatry. 1985;42(7):725-728. Tooth LR, Ottenbacher KJ. The kappa statistic in rehabilitation research: an examination. Arch Phys Med Rehabil. 2004;85(8):1371-1376.

25. Portney L, Watkins M. Foundations of clinical research: applications to practice. 2nd ed. Upper Saddle River, NJ: Pearson/Prentice Hall; 2000. 26. Portney L, Watkins M. Foundations of clinical research: applications to practice. 3rd ed. Upper Saddle River, NJ: Pearson/Prentice Hall; 2009. 27. Kappa measurement of inter-observer agreement multicalcÂŽ. MedCalc 3000. http://www.hsls.pitt.edu/ medcalc/Kappa_MC.htm. 28. Gribble P, Brigle J, Pietrosimone B, PďŹ le K, Webster K. Intrarater Reliability of the Functional Movement Screen. J Strength Cond Res. 2013;27(4):978-981. 29. Minick K, Kiesel K, Burton L, Taylor A, Plisky P, Butler R. Interrater reliability of the functional movement screen. J Strength Cond Res. 2010;24(2):479-486.

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Appendix A

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Appendix B

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Appendix C

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IJSPT

ORIGINAL RESEARCH

HIP RANGE OF MOTION IN RECREATIONAL WEIGHT TRAINING PARTICIPANTS: A DESCRIPTIVE REPORT Scott Cheatham, PhD, DPT, PT, OCS, ATC, CSCS William J. Hanney, PT, DPT, PhD Morey J. Kolber, PT, PhD, OCS, Cert. MDT, CSCS*D

ABSTRACT Background: The surveillance of hip injuries and risk factors have become an emerging focus in sports medicine due to the increased recognition of hip pathologies. Researchers suggest that decreased hip range of motion (ROM) is a risk factor for injury in various athletic activities. One under reported population that has potential for hip injuries is recreational weight training (WT) participants. Currently, no studies have reported hip ROM values in WT participants which creates a knowledge gap in this population. Purpose: The purpose of this study was to report hip passive ROM values of WT participants to develop reference data for future research on injury patterns and prevention strategies for this population. Study Design: Descriptive cross sectional study Methods: Two-hundred healthy recreational adult WT participants (age = 27.18 ± 9.3 years, height = 174.84 ± 9.8 cm, mass = 91.0 ± 17.9 kg, body mass index = 29.6 ± 4.5 kg/m2) were recruited. Bilateral hip passive ROM was assessed for flexion, extension, internal rotation, external rotation, and abduction. Statistical analysis included subject demographics (means and SD) and a two-tailed independent t-test to compare mean passive hip ROM values between sexes and hips. Statistical significance was considered p < .05. Results: A total of 400 hundred hips (right + left) were measured for this analysis. When comparing hip ROM values within sexes, men had no significant difference (p≥.28) between the right and left hip for all motions. Women did have a significant difference (p≤.05) between the right and left hip for all motions. The right hip had lower values for all motions than the left hip suggesting a more global decrease in right hip ROM. When comparing hip ROM values between men and women, there was a significant difference (p≤.05) between men and women for all motions. Men had lower ROM values for all hip motions when compared to women. Conclusion: This is the first investigation to provide a descriptive analysis of hip ROM in healthy recreational WT participants. These data provide a starting point for clinicians and researchers to further study this population for injury prevention. Evidence Level: 2 Key words: Exercise, hip joint, injury, mobility, prevention

1

California State University Dominguez Hills, Carson, CA, USA University of Central Florida, Orlando, FL, USA 3 Nova Southeastern, Ft. Lauderdale, FL, USA 2

CORRESPONDING AUTHOR Scott Cheatham, PhD, DPT, PT, OCS, ATC, CSCS Division of Kinesiology California State University Dominguez Hills 1000 E. Victoria St. Carson, CA 90747 E-mail: Scheatham@csudh.edu

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INTRODUCTION It has been estimated that approximately 45 million Americans participate in some form of resistance training two or more times a week.1 From a benefit perspective, resistance training improves both health and fitness attributes. Specifically, researchers suggest that resistance training may have a positive effect on muscle performance, bone mineral density, and function.2-4 Although the benefits of resistance training have been well documented, participation is not without risk as a significant number of injuries have been reported in the literature. Approximately 25% of those that participate in weight-training (WT), a form of resistance training, report injuries severe enough for which they sought medical attention.5 It has been reported that WT participants sustained, on average, 2.4-3.3 injuries per 1000 hours of activity.6,7 Injuries to the shoulder, low back, and knee are the most reported injuries among this population.7,8 Recently, injuries to the hip have received more attention due to improved recognition of pathology and the advent of hip arthroscopy.9 Reports of hip injuries among individuals who weight train are lacking in the literature. Among the available studies, Jonasson et al10 reported that 31% of WT injuries were hip related in a sample of 21 male weightlifters and Kulund et al11 reported a 3% hip injury rate among 80 male weightlifters. Unfortunately, the WT population has not been studied in detail to determine the future risk for chronic musculoskeletal condition such as hip osteoarthritis. Nevertheless, many of the occupational risk factors identified for hip Osteoarthritis (OA) seemingly resemble WT activities (e.g. climbing, squatting, lifting).12 Of interest to sports medicine professionals, is the association between hip range of motion (ROM) and the potential for injury in the WT population. The connection between hip ROM deficits and injury has been reported for other athletic activities. For baseball, a higher risk of shoulder,13 elbow,14 and groin injuries15 have been found in players with hip ROM deficits. Hip ROM deficits have also been associated with hip, groin, and knee injuries in soccer,16-19 tennis20 and ice hockey.21 These data provide insight into a potential risk factor for hip injury among these athletic activities which may also be a risk factor in the WT population. To date, a paucity of data has

been directly reported in the WT population which creates a gap in the knowledge regarding this potential connection. Furthermore, clinicians must rely on previously published normative data on hip ROM and attempt to apply the values when treating clients who WT.22 Other sports such as soccer,19 baseball,23,24 tennis, 25 dance26 and golf27 have published reference ROM values. The WT population lacks adequate reporting of hip ROM values and it is not unreasonable to postulate that a difference may exist when compared to the general population as a result of training patterns. Published studies on individuals who participate in WT have focused on hip motion for specific movements such as the squat,28,29 lunge30 or the step down movement.31 To date, no studies have reported hip ROM values for these individuals. Thus, the purpose of this study was to report passive hip ROM values of WT participants to develop reference data for future research on injury patterns and prevention strategies for this population. METHODS This descriptive cross sectional study involved the measurement of passive hip ROM in recreational WT participants. This study was approved by the University of Central Florida institutional review board (IRB # IRB00001138). Participants A convenience sample of 200 recreational WT participants (400 hips) 18-59 years were recruited via flyers and word of mouth from the university campus, local health clubs, and gymnasiums (Table 1). The inclusion criteria included: history of WT for at least one year and current participation in recreational WT at least two times per week. Exclusion criteria included: current complaint of hip injury or pain, prior surgery to hip joint, and any medical or musculoskeletal condition that would prevent testing. Additionally, participants were excluded if they were currently participating in competitive sports or had a current or past history of competitive bodybuilding or power-lifting. All participants who qualified received detailed information of the study requirements and were required to speak and read English to complete the university approved consent process prior to participation.

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Table 1. Subject Demographics.

Instrumentation Measurement of bilateral passive hip flexion, extension, abduction, internal rotation (IR) and external rotation (ER) ROM was performed and measured with a standard goniometer. Standard goniometry has shown to be a valid and reliable instrument for measuring hip ROM.32-35 Pilot Study Prior to data collection, a pilot study was conducted to determine intersession reliability. Two examiners participated in data collection for this study. The goniometric measurements were performed on 20 independent participants chosen for this portion of the study. The Intraclass Correlation Coefficient (ICC) was used to calculate intersession (ICC model 2, k (95% CI)) reliability.36 For the reliability analysis, a single measurement of the right and left hip were taken and the mean of the two values were used. For passive hip ROM, there was good intersession reliability for IR ICC=0.90 (.87-.92), ER ICC=0.89 (.84-.91), flexion ICC= 0.84 (0.78–0.88), abduction ICC=0.90 (0.86-0.92), and extension ICC=0.81 (.75-.85) ROM. The standard error of measurement (SEM) ranged from 3-degrees for abduction, ER, and IR to 4 degrees for flexion and extension. SEM values were rounded to the nearest degree to reflect the smallest unit available on a goniometer. Procedures All measurement were performed in a climate controlled environment and performed based on previously described measurement procedures.37,38 All

subjects underwent the same testing procedures by two examiners. Subjects were blinded to the results and from other subjects participating in the study. No practice or warm-up was performed prior to testing. The following procedures for each motion is described below. Hip Flexion ROM. The subject was positioned supine on an examination table. The examiner passively flexed the subject’s hip as far as possible with the opposite leg extended. The goniometer was centered at the greater trochanter, aligning one arm along the center of the thigh and the other arm aligned horizontally as illustrated in Figure 1. The examiner monitored for any aberrant pelvic motion prior to taking measurement.37

Figure 1. Goniometric measurement of supine hip flexion.

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Figure 3. Goniometric measurement of seated hip internal rotation.

the end of the available range until an “unyielding” end-feel was felt and then took the measurementas illustrated in Figure 3. 37,38 . The examiner provided verbal cues if the participant compensated in any way to ensure no substitute movements occurred during testing. Figure 2. Goniometric measurement of side lying hip extension.

Hip Extension ROM. The subject was positioned in the sidelying position on the examination table with the test extremity facing upward. The lowermost extremity was flexed at the hip to 45 degrees and at knee to 90 degrees. The examiner passively extended the hip with knee straight as far as possible. The goniometer was centered at the greater trochanter aligning one arm of goniometer over the center of the thigh and the other arm along a zero-degree position as illustrated in Figure 2. The examiner monitored for any aberrant lumbopelvic motion prior to and during the measurement.37 Hip IR ROM. The subject was sitting on an examination table with their knees flexed to 90° and feet unsupported. The examiner stood in front of the test leg and centered the goniometer at the lower border of the patella with the arm of the goniometer aligned along the patellar tendon and the other arm aligned vertically. The examiner passively moved the participant’s hip into IR, keeping their leg in neutral, to

Hip ER ROM. The subject was sitting on an examination table with their knees flexed to 90° and feet unsupported. The examiner stood in front of the test leg and centered the goniometer at the lower border of the patella with the arm of the goniometer aligned along the patellar tendon and the other arm aligned vertically. The examiner passively moved the participant’s hip into ER, keeping their leg in neutral, to the end of the available range until an “unyielding” end-feel was felt and then took the measurement as illustrated in Figure 4.37,38 The examiner provided verbal cues if participant compensated in any way to ensure no substitute movements occurred during testing. Hip Abduction ROM. The subject was positioned supine on the examination table with legs extended. The examiner stood on the side of the test leg. The goniometer was centered midway between the subject’s anterior superior iliac spine and pubic symphysis, aligning one arm centrally over their thigh. The examiner passively abducted the subject’s leg as far as possible, without causing any aberrant pelvic motion, and then took the measurement as illustrat-

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Figure 4. Goniometric measurement of seated hip external rotation.

Figure 5. Goniometric measurement of supine hip abduction.

ed in Figure 5. 37 The examiner monitored for any aberrant lumbopelvic motion prior to and during the measurement.37

RESULTS Participant demographic data is presented in Table 1. Both men and women reported participation in WT a mean 3.4 times per week with no significant differences between men and women (p = .88). Training experience was reported at a mean of 5.9 years for women and 7.8 years for men. Significant differences for training experience were not found (p = .22). Tables 2 and 3 present mean passive ROM values. When comparing hip ROM values among sexes, men had no significant differences (p≼.28) between the right and left hip for all motions. Women did have a significant differences (p≤.05) between the right and left hip for all motions. The right hip had lower values for all motions than the left hip suggesting a more global decrease in right hip PROM (Table 3). When comparing hip ROM values between men and women, there was a significant difference

Statistical Analysis Statistical analysis was performed using SPSS version 24.0 (IBM SPSS, Chicago, IL, USA). Participant descriptives were calculated and reported as the mean and standard deviation (SD) for age, height, mass, body mass index, and ROM values. A twotailed independent t-test was used to compare mean passive hip ROM values between the right and left leg to determine asymmetries as well as to compare men and women. Statistical significance was considered as p< 0.05. The SEM was calculated for the reliability pilot study using a previously established formula SEM = standard deviation multiplied by the square root of 1-ICC value.39

Table 2. Hip ROM Values for Recreational Weight Training Participants.

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Table 3. Comparison between Right and Left Hip ROM among Sexes.

Table 4. Comparison between Male and Female Recreational Weight Training Participants.

(p≤.05) between men and women for all motions. Men had lower ROM values for all right and left hip motions when compared to women (Table 4).

may help to further classify these individuals for future research on injury surveillance and prevention strategies.

DISCUSSION This is the first investigation to report hip passive ROM values in recreational WT participants. This group has been understudied compared to other athletic groups which leaves a gap in the knowledge regarding hip ROM and the potential risk for injury. These results provide reference hip ROM values that

The results of the study suggest that among recreational WT participants, women have greater hip ROM in all motions (p≤.05) than men. This is consistent with prior research reporting greater hip ROM values in adult women when compared to adult men.22,40 However, it is often difficult to make a direct comparison among populations due to the

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variation in study methodology and the procedure by which ROM may be tested. Currently, there is no standard method for measuring hip ROM since many researchers measure both active and passive ROM in the supine, prone, sidelying, and seated positions.41,42 With this being stated, the passive ROM findings of this investigation are limited to the specific procedures used. This is a necessary consideration as prone hip ER and IR may have produced different values. When comparing results from this study to published reference values, only one comparable study was found that used similar methods for measuring passive hip IR and ER in adults.40 The WT men and women in the current study had lower seated passive hip IR (right +left) (31.1째 versus 37.9째) and ER (right + left) (36.2째 versus 40.7째) when compared to the published adult values of Kouyoumdjian et al.40 Potential reasons for the differences reside in measurement technique (e.g. positioning), procedure, and age. In the Kouyoumdjian et al study subjects were older (mean age 39.1 years), measurements were performed in supine and prone, and a digital camera with software was used to quantify ROM.40 Injuries to the lower extremities have been reported among elite competitive weightlifters and powerlifters but not in recreational WT participants.6,8,43 Researchers are just beginning to report injuries specific to the hip among general WT participants. Polesello et al44 reported on 47 individuals who underwent arthroscopic surgery for hip labral tears and chondral lesions after developing painful symptoms associated with the leg press and squat which are common WT movements. The researchers reported the post-surgical outcomes but did not provide any insight regarding the correlation between the WT movements, hip ROM, and the diagnosed hip injuries. Other researchers have evaluated pre-surgical and post-surgical unilateral and bilateral squat performance in individuals with femoral acetabular impingement (FAI). The researchers observed decreased squat depth, hip internal rotation, and decreased posterior pelvic tilt in individuals with CAM-type FAI.9,45,46 Researchers have also observed that squat performance improved postsurgically with subjects having a greater squat depth and pelvic motion.9 Despite these reported finding,

the researchers did not discuss if the squat movement was a risk factor for injury which leaves a gap in our understanding of this common exercise.9,45,46 Future research is necessary to examine the correlation between common WT movements, the required hip ROM, and risk of hip injury. The data from this study provides a beginning for clinicians to understand common hip ROM values in the WT population. Impaired hip ROM may be a relative factor needing to be considered for injury prevention and athletic performance, thus should be considered for inclusion when prescribing exercises for these individuals.14,19,23 These data are the first to be reported among WT participants, thus should be considered for clinical practice when managing such patients. WT participants may have different values based upon the types of WT activities, performed, thus general population normative values may not be relevant. When interpreting differences in ROM values between men and women as well as side-to-side differences it should be recognized that a statistically significant difference does not necessarily mean a clinically important difference nor does it mean error in the measurement is accounted for. Moreover, it is not unreasonable for mean and women to have differences given the potential for training differences as well as body morphology. One way to determine the error in a measurement is to consider the SEM. The SEM is an index of the expected variation of a score due to measurement error. The SEM is reported in terms of specific value and as a confidence interval around a mean. One SEM value represents 68% of the population. For example, the results of this study suggest that women have statistically greater bilateral hip ROM when compared to men. As an example, when comparing the mean angle of right hip abduction for men (41.9 degrees) to women (44.4 degrees) a difference of 2.5 degrees is present. While this difference is statistically significantly different, the SEM for hip abduction is 3 degrees. This suggests that the angles reported will vary +/- 3 degrees (68% of the time) from the mean for men and women, thus the difference may reflect error.

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Limitations When considering the methodology of this descriptive study, several limitations need to be discussed. First, this investigation reported values in healthy subjects which limits the generalizability of these results to this population. However, no reference data has been reported in this population, thus the information provided may guide practice or be used for reference values. Second, weight-training participants comprise a heterogeneous population and variability within training patterns and styles may indeed influence mobility. The effort to use only recreational participants was an attempt to capture a homogenous subgroup, however, subjects were not grouped according to a specific intensity level of exercise which may have influenced hip ROM values. Perhaps a further classification based on such variables may help guide injury prevention strategies. Third, passive hip IR and ER ROM were measured in the seated position where other investigations have measured hip ROM in different positions.47-49 This must be considered when interpreting these results or comparing to other values to inform clinical practice. Fourth, hip adduction measurements were omitted which limits the understanding of the complete range of hip mobility in these participants. Lastly, standard goniometry was used in lieu of a digital device, as the standard goniometer is a common tool used in the clinical setting.32-35 Future Research Future research should focus on prospective injury surveillance among recreational WT participants. Given the recent evidence associating hip ROM deficits and athletic injuries, future research in warranted in this population.13-15,50-52,20,21 Also, attempts to further classify the recreational WT participant according to the type of weight training and level of training may assist in providing a better understating of subgroups based on WT activities. This may provide insight into common mechanisms of injury related to specific weight training activities and help guide injury prevention strategies. Finally, it would be beneficial for future studies to capture hip adduction range of motion and limited mobility in this plane may have consequences in terms of function and sport participation.

CONCLUSION This study reported passive hip ROM values in recreational WT participants. Women WT participants had asymmetrical passive hip ROM whereas men had symmetrical measurements. With regard to sex, men had lower overall hip ROM compared to women. Implications for these findings may include the use of clinical efforts to increase global ROM in men, whereas women should focus on symmetry. Lastly the right hip had grossly lower ROM values among all participants, which may suggest a participation type dominance which could be addressed with efforts to achieve symmetry. This is the first study to report reference data for recreational WT participants which provides a starting point for future research. Future investigations should focus on injury surveillance and injury prevention strategies in this population. REFERENCES 1. Trends in strength training--United States, 1998-2004. MMWR Morb Mortal Wkly Rep. 2006;55(28):769-772. 2. Tonnesen R, Schwarz P, Hovind PH, et al. Physical exercise associated with improved BMD independently of sex and vitamin D levels in young adults. Eur J Appl Physiol. 2016;116(7):1297-1304. 3. Mosti MP, Carlsen T, Aas E, et al. Maximal strength training improves bone mineral density and neuromuscular performance in young adult women. J Strength Cond Res. 2014;28(10):2935-2945. 4. Garber CE, Blissmer B, Deschenes MR, et al. American College of Sports Medicine position stand. Quantity and quality of exercise for developing and maintaining cardiorespiratory, musculoskeletal, and neuromotor ďŹ tness in apparently healthy adults: guidance for prescribing exercise. Med Sci Sports Exerc. 2011;43(7):1334-1359. 5. Powell KE, Heath GW, Kresnow MJ, et al. Injury rates from walking, gardening, weightlifting, outdoor bicycling, and aerobics. Med Sci Sports Exerc. 1998;30(8):1246-1249. 6. Raske A, Norlin R. Injury incidence and prevalence among elite weight and power lifters. Am J Sports Med. 2002;30(2):248-256. 7. Aasa U, Svartholm I, Andersson F, et al. Injuries among weightlifters and powerlifters: a systematic review. Br J Sports Med. 2016. 8. Calhoon G, Fry AC. Injury rates and proďŹ les of elite competitive weightlifters. J Athl Train. 1999;34(3):232-238.

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9. Lamontagne M, Brisson N, Kennedy MJ, et al. Preoperative and postoperative lower-extremity joint and pelvic kinematics during maximal squatting of patients with cam femoro-acetabular impingement. J Bone Joint Surg Am. 2011;93 Suppl 2:40-45. 10. Jonasson P, Halldin K, Karlsson J, et al. Prevalence of joint-related pain in the extremities and spine in five groups of top athletes. Knee Surg Sports Traumatol Arthrosc. 2011;19(9):1540-1546. 11. Hanson PG, Angevine M, Juhl JH. Osteitis Pubis in Sports Activities. Physician sports med. 1978;6(10): 111-114. 12. Cheatham SW, Kolber MJ. Orthopedic Management of the Hip and Pelvis. Elsevier - Health Sciences Division; 2015. 13. Scher S, Anderson K, Weber N, et al. Associations among hip and shoulder range of motion and shoulder injury in professional baseball players. J Athl Train. 2010;45(2):191-197. 14. Saito M, Kenmoku T, Kameyama K, et al. Relationship Between Tightness of the Hip Joint and Elbow Pain in Adolescent Baseball Players. Orthop J Sports Med. 2014;2(5):2325967114532424. 15. Li X, Ma R, Zhou H, et al. Evaluation of Hip Internal and External Rotation Range of Motion as an Injury Risk Factor for Hip, Abdominal and Groin Injuries in Professional Baseball Players. Orthop Rev (Pavia). 2015;7(4):6142. 16. Tak I, Glasgow P, Langhout R, et al. Hip Range of Motion Is Lower in Professional Soccer Players With Hip and Groin Symptoms or Previous Injuries, Independent of Cam Deformities. Am J Sports Med. 2016;44(3):682-688. 17. Ellera Gomes JL, Palma HM, Ruthner R. Influence of hip restriction on noncontact ACL rerupture. Knee Surg Sports Traumatol Arthrosc. 2014;22(1):188-191. 18. Gomes JL, de Castro JV, Becker R. Decreased hip range of motion and noncontact injuries of the anterior cruciate ligament. Arthroscopy. 2008;24(9):1034-1037. 19. Nguyen AD, Zuk EF, Baellow AL, et al. Longitudinal Changes in Hip Strength and Range of Motion in Female Youth Soccer Players: Implications for ACL Injury. A Pilot Study. J Sport Rehabil. 2016. 20. Young SW, Dakic J, Stroia K, et al. Hip range of motion and association with injury in female professional tennis players. Am J Sports Med. 2014;42(11):2654-2658. 21. Wilcox CR, Osgood CT, White HS, et al. Investigating Strength and Range of Motion of the Hip Complex in Ice Hockey Athletes. J Sport Rehabil. 2015;24(3):300306.

22. Simoneau GG, Hoenig KJ, Lepley JE, et al. Influence of hip position and gender on active hip internal and external rotation. J Orthop Sports Phys Ther. 1998;28(3):158-164. 23. Picha KJ, Harding JL, Bliven KC. Glenohumeral and Hip Range-of-Motion and Strength Measures in Youth Baseball Athletes. J Athl Train. 2016;51(6):466-473. 24. Sauers EL, Huxel Bliven KC, Johnson MP, et al. Hip and glenohumeral rotational range of motion in healthy professional baseball pitchers and position players. Am J Sports Med. 2014;42(2):430-436. 25. Moreno-Perez V, Ayala F, Fernandez-Fernandez J, et al. Descriptive profile of hip range of motion in elite tennis players. Phys Ther Sport. 2016;19:43-48. 26. Bennell KL, Khan KM, Matthews BL, et al. Changes in hip and ankle range of motion and hip muscle strength in 8-11 year old novice female ballet dancers and controls: a 12 month follow up study. Br J Sports Med. 2001;35(1):54-59. 27. Gulgin H, Armstrong C, Gribble P. Weight-bearing hip rotation range of motion in female golfers. N Am J Sports Phys Ther. 2010;5(2):55-62. 28. Kim SH, Kwon OY, Park KN, et al. Lower extremity strength and the range of motion in relation to squat depth. J Hum Kinet. 2015;45:59-69. 29. Schutz P, List R, Zemp R, et al. Joint angles of the ankle, knee, and hip and loading conditions during split squats. J Appl Biomech. 2014;30(3):373-380. 30. Riemann BL, Lapinski S, Smith L, et al. Biomechanical analysis of the anterior lunge during 4 external-load conditions. J Athl Train. 2012;47(4):372-378. 31. Bell-Jenje T, Olivier B, Wood W, et al. The association between loss of ankle dorsiflexion range of movement, and hip adduction and internal rotation during a step down test. Man Ther. 2016;21:256-261. 32. Holm I, Bolstad B, Lutken T, et al. Reliability of goniometric measurements and visual estimates of hip ROM in patients with osteoarthrosis. Physiother Res Int. 2000;5(4):241-248. 33. Nussbaumer S, Leunig M, Glatthorn JF, et al. Validity and test-retest reliability of manual goniometers for measuring passive hip range of motion in femoroacetabular impingement patients. BMC Musculoskelet Disord. 2010;11:194. 34. Pua YH, Wrigley TV, Cowan SM, et al. Intrarater test-retest reliability of hip range of motion and hip muscle strength measurements in persons with hip osteoarthritis. Arch Phys Med Rehabil. 2008;89(6):1146-1154. 35. Roach S, San Juan JG, Suprak DN, et al. Concurrent validity of digital inclinometer and universal goniometer in assessing passive hip mobility in

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36.

37.

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44.

healthy subjects. Int J Sports Phys Ther. 2013;8(5): 680-688. Portney LG, Watkins MP. Foundations of Clinical Research: Applications to Practice. Pearson/Prentice Hall; 2009. Cibere J, Thorne A, Bellamy N, et al. Reliability of the hip examination in osteoarthritis: effect of standardization. Arthritis Rheum. 2008;59(3):373-381. Shimamura KK, Cheatham S, Chung W, et al. Regional interdependence of the hip and lumbopelvic region in divison ii collegiate level baseball pitchers: a preliminary study. Int J Sports Phys Ther. 2015;10(1):1-12. Kolber MJ, Hanney WJ. The reliability, minimal detectable change and construct validity of a clinical measurement for identifying posterior shoulder tightness. N Am J Sports Phys Ther. 2010;5(4):208-219. Kouyoumdjian P, Coulomb R, Sanchez T, et al. Clinical evaluation of hip joint rotation range of motion in adults. Orthop Traumatol Surg Res. 2012;98(1):17-23. Martin HD, Kelly BT, Leunig M, et al. The pattern and technique in the clinical evaluation of the adult hip: the common physical examination tests of hip specialists. Arthroscopy. 2010;26(2):161-172. Kouyoumdjian P, Coulomb R, Sanchez T, et al. Clinical evaluation of hip joint rotation range of motion in adults. Orthop Traumalol Surg Res. 2012;98(1):17-23. Keogh J, Hume PA, Pearson S. Retrospective injury epidemiology of one hundred one competitive Oceania power lifters: the effects of age, body mass, competitive standard, and gender. J Strength Cond Res. 2006;20(3):672-681. Polesello GC, Cinagawa EH, Cruz PD, et al. Surgical treatment for femoroacetabular impingement in a

group that performs squats. Rev Bras Ortop. 2012;47(4):488-492. 45. Bagwell JJ, Snibbe J, Gerhardt M, et al. Hip kinematics and kinetics in persons with and without cam femoroacetabular impingement during a deep squat task. Clin Biomech (Bristol, Avon). 2016;31:87-92. 46. Lamontagne M, Kennedy MJ, Beaule PE. The effect of cam FAI on hip and pelvic motion during maximum squat. Clin Orthop Relat Res. 2009;467(3):645-650. 47. Robb AJ, Fleisig G, Wilk K, et al. Passive Ranges of Motion of the Hips and Their Relationship With Pitching Biomechanics and Ball Velocity in Professional Baseball Pitchers. Am J Sports Med. 2010;38(12):2487-2493. 48. Ellenbecker TS, Ellenbecker GA, Roetert EP, et al. Descriptive ProďŹ le of Hip Rotation Range of Motion in Elite Tennis Players and Professional Baseball Pitchers. Am J Sports Med. 2007;35(8):1371-1376. 49. Laudner K, Wong R, Onuki T, et al. The relationship between clinically measured hip rotational motion and shoulder biomechanics during the pitching motion. J Sci Med Sport. 2014. 50. Sadeghisani M, Manshadi FD, Kalantari KK, et al. Correlation between Hip Rotation Range-of-Motion Impairment and Low Back Pain. A Literature Review. Ortop Traumatol Rehabil. 2015;17(5):455-462. 51. Van Dillen LR, Bloom NJ, Gombatto SP, et al. Hip rotation range of motion in people with and without low back pain who participate in rotation-related sports. Phys Ther Sport. 2008;9(2):72-81. 52. Roach SM, San Juan JG, Suprak DN, et al. Passive hip range of motion is reduced in active subjects with chronic low back pain compared to controls. Int J Sports Phys Ther. 2015;10(1):13-20.

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IJSPT

ORIGINAL RESEARCH

DEVELOPMENT OF A SCREENING PROTOCOL TO IDENTIFY INDIVIDUALS WITH DYSFUNCTIONAL BREATHING Kyle Kiesel, PT, PhD1 Tonya Rhodes1 Jacob Mueller, ATC1 Alyssa Waninger1 Robert Butler, PT, PhD2

ABSTRACT Introduction: Dysfunctional breathing (DB) has been linked to health conditions including low back pain and neck pain and adversely effects the musculoskeletal system. Individuals with DB often have decreased pain thresholds and impaired motor control, balance, and movement. No single test or screen identifies DB, which is multi-dimensional, and includes biochemical, biomechanical, and psychophysiological components. Several tools assess and test for DB, but no screen exists to determine whether additional testing and assessment are indicated. Purpose/Background: The purpose of this study was to develop a breathing screening procedure that could be utilized by fitness and healthcare providers to screen for the presence of disordered breathing. A diagnostic test study approach was utilized to establish the diagnostic accuracy of the newly developed screen for DB. Methods: A convenience sample of 51 subjects (27 females, 27.0 years, BMI 23.3) were included. To test for DB related to the biochemical dimension, end-tidal CO2 (ETCO2) was measured with a capnography unit. To test for DB related to biomechanical dimension, the Hi-Lo test was utilized. To test for DB related to the psychophysiological dimension, the Self Evaluation of Breathing Symptoms Questionnaire (SEBQ) and Nijmegen questionnaires were utilized. Potential screening items that have been shown to be related to DB in previous research and that could be performed by non-health care personnel were utilized to create the index test including activity level, breath hold time (BHT), respiration rate, and the Functional Movement Screen (FMS™). Results: There were no strong correlations between the three measures of DB. Five subjects had normal breathing, 14 failed at least one measure, 20 failed at least two, and 12 failed all three. To develop screening items for each dimension, data were examined for association with failure. BHT and a four-item mini-questionnaire were identified as the most closely associated variables with failure of all three dimensions. A BHT of <25 seconds and four questions were combined and yielded a sensitivity of 0.89 (0.85-0.93) and a specificity of 0.60 (0.18-0.92) for clinical identification of DB. Conclusion: Easily obtained clinical measures of BHT and four questions can be utilized to screen for the presence of DB. If the screen is passed, there is an 89% chance that DB is not present. If the screen is failed, further assessment is recommended. Level of Evidence: 2b Key Words: Breath holding, disordered breathing, hypocapnia, sensitivity

1 2

University of Evansville, Evansville, IN, USA Director of Performance, St. Louis Cardinals, St. Louis, MO, USA

The Institutional Review Board at the University of Evansville approved this study Funding provided through the Ridgway Student Research Award from the University of Evansville

CORRESPONDING AUTHOR Kyle Kiesel Professor of Physical Therapy University of Evansville 1800 Lincoln Avenue Evansville, Indiana 47722 USA E-mail: Kk70@evansville.edu

The International Journal of Sports Physical Therapy | Volume 12, Number 5 | October 2017 | Page 774 DOI: 10.16603/ijspt20170774

INTRODUCTION Dysfunctional breathing (DB) is a commonly occurring condition in the general population. It is estimated that as high 50-80% of adults have some level of DB.1,2 The term DB has been created to identify those individuals who display divergent breathing patterns and have breathing problems that cannot be attributed to a specific medical diagnosis, such as asthma.3 Normal breathing, considered to be diaphragmatic breathing, includes synchronized motion of the upper rib cage, lower rib cage, and abdomen and requires proper use of the diaphragm.4 DB has been linked to a number of common chronic health conditions such as low back pain (LBP),5,6 neck pain,7 anxiety,8 and depression.2 It has been reported that approximately 50% of individuals with LBP9 and 83% of individuals with anxiety demonstrate some form DB.10 A wide-range of individuals likely possess some level of DB, and currently there is no widely accepted screen or index test that exists to identify these individuals.2 Identification and subsequent intervention for those with DB may be an important missing component of musculoskeletal health care as DB is known to be associated with many common musculoskeletal conditions and may also be a risk factor for the development of musculoskeletal dysfunction.11 DB may be an important factor to consider relative to the prevention and recurrence of movement oriented dysfunction12 and, therefore, may have a place in conditioning and fitness programs as well. The primary reason to screen for DB in individuals who are physically active or currently have musculoskeletal pain is its close relationship with normal core function.9,13 To better understand core structure and function as it relates to DB, it is important to note the core can be divided into two basic anatomical units,14 the outer core and the inner core. The outer core is composed of large multiarticular muscles such as the erector spinae, rectus abdominis, and external obliques. The function of the outer core is to provide postural stability, resist external load, produce movement, and transfer rotational energy for activities such as throwing and hitting.15 The inner core can be conceived as a cylinder made up of the pelvic floor as the base, the diaphragm as the top, the transverse abdominis muscle as the anterior border, and the

lumbar multifidus muscles as the posterior border.16 The function of the inner core is both physiological and mechanical, its main role is to provide the muscle activation required to sustain respiration, continence, and segmental spinal stabilization.16 The inner core receives ongoing subconscious input from the central nervous system (CNS), which automatically maintains respiration,9 continence, and segmental stabilization in anticipation of a spinal perturbation. This is a highly automated, delicately functioning system with the ability to simultaneously regulate physiological functions (respiration and continence) while allowing for control of translation and shear forces (segmental stabilization) between spinal segments during both low and high load activities.17 Core muscle dysfunction, including atrophy and abnormal activation, has been linked to many common musculoskeletal problems including LBP,9 ACL injury,18 neck pain,7 and an overall increased injury risk.19 Subjects with DB have been shown to demonstrate concurrent core dysfunction including altered postural responses during limb movements5 and altered inner core muscle activation.9,13 Further, normal breathing has been described as forming the foundation for all movement patterns12 while DB has been shown to be related to clinical measures of dysfunctional movement with subjects with DB scoring lower on the Functional Movement Screen (FMS™) than those with normal breathing.11 It is thought that core muscle function is altered in those with DB in a compensatory manner. The physiological drive to maintain respiration leads to core muscles functioning to assist breathing to a greater extent than during normal functional breathing.16,20 This relationship between normal breathing and core function is so intimately linked that perhaps the most fundamental assessment of core function should start with some type of breathing screen or test. Core exercises are often prescribed as part of rehabilitation, fitness, and strength and conditioning programs with no attention paid to breathing function. It may be desirable for fitness and health care professionals who prescribe core exercises to utilize a breathing screen to determine if subsequent breathing pattern assessment and treatment is necessary in conjunction with planned rehabilitation, training, or conditioning.

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There is currently no accepted screening procedure to identify if a person may have DB and, therefore, requires further testing and assessment. Research has shown that DB is multi-dimensional, calling for a variety of tests needed for an accurate diagnosis.11 Recently, researchers have identified the three most common dimensions or categories of DB which include the biochemical, biomechanical and psychophysiological dimensions.21 It has been suggested that any comprehensive assessment for DB should include tools that capture all three of these dimensions as they are often found to be independent from each other. The biomechanical dimension of DB refers to individuals who are in an abnormal mechanical breathing pattern. A subject demonstrating a breathing pattern disorder would be lacking what is considered a normal diaphragmatic breathing pattern while at rest. A clinical measure to determine presence of DB in the biomechanical dimension is the Hi-Lo Breathing Assessment. The most common disordered breathing pattern at rest is described as upper chest breathing or apical breathing. In this pattern, an upper chest expansion is dominant during the inspiratory phase of breathing.22 Another example of a disordered breathing pattern has been described as a paradoxical pattern where the lower abdomen is drawn in, rather than outward, during the inspiratory phase.23 The biochemical dimension refers to individuals who are in a state of hypocapnia demonstrating reduced levels of CO2 in the blood. Capnography is a reliable and time sensitive clinical measure of respiratory function that measures the partial pressure of CO2 in exhaled air termed end tidal CO2 (ETCO2).24,25 ETCO2 has good concurrent validity when compared to direct blood measures. A value of 35 mmHg and below is commonly used as a cutpoint to define hyocapnia.26 The psychophysiological dimension, sometimes called the breathing symptoms dimension, is the least commonly identified and explored category of DB and is characterized by individuals who may breathe normally during most daily activities, however, breathing may become abnormal in certain, often stressful situations. This suggests a lack of the individual’s system to adapt to a meaningful

breathing strategy at times; however, the system does have the ability to function in a normal manner. In such cases, measures of DB can often appear normal during routine clinical testing. Self-reported questionnaires may be useful capture this dimension of DB and include the Nijmegen Questionnaire,27 and the more recently developed Self Evaluation of Breathing Symptoms Questionnaire (SEBQ). The SEBQ was developed, in part, to assess respiratory symptoms and breathing behaviors reported to be associated with DB for individual who may not demonstrate consistent breathing dysfunction in the biomechanical or biochemical dimensions.21 While there are several assessment and testing tools described in the literature to identify individuals with each of the three different dimensions of DB, no one reference test has emerged that can be used to capture all three dimensions. Currently, there is no accepted clinical screening procedure to determine if a subject could even benefit from further breathing assessment and testing. Therefore, there is a need for a breathing screening procedure that could be utilized by both fitness and healthcare professionals. A screen, defined as “a preliminary procedure, such as a test or examination, to detect the most characteristic sign or signs of a disorder that may require further investigation� should be highly sensitive in nature.28 That is, when the screening procedure yields a negative result (passing the screen), the tester is confident that the condition does not exist. When the screening procedure yields a positive result (not passing the screen), the condition may exist and further testing and assessment is warranted. Because of the growing evidence linking DB to a wide variety of health conditions, a sensitive screening tool, designed to capture those individuals who would likely benefit from a detailed breathing assessment and subsequent intervention, would be desirable. If a battery of tests can be combined and used as a screen to identify those in the fitness and general population who have disordered breathing, it could be deployed as a screening tool for disordered breathing in the fitness and general population. Therefore, the purpose of this study was to develop a breathing screening procedure that could be utilized by fitness and healthcare providers to screen for the presence of disordered breathing.

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METHODS Subjects: A convenience sample of 51 individuals, including 27 females, (26.5 years, BMI 22.7) and 24 males (28.3 years, BMI 24.9) consented for participation in this study which was approved by the Institutional Review Board at the University of Evansville. Data for this prospective diagnostic test study were collected in a University lab setting from September to November 2015. Potential subjects were excluded if they were currently participating in rehabilitation for any disorder, if they had a neurological or cardiovascular comorbidity known to impair musculoskeletal function, or if they could not read or speak English. To determine if DB was present, reference measures were obtained for each of the three dimensions of DB. The data collection process was done in the same manner at each data collection session with the same three testers performing the same tests each time in the same order. The reference measures and the potential screening tests measures were combined in a manner that was designed to be as efficient as possible and allowed for blinding of the testers to the results of the reference measures. After consent was obtained, resting capnography data was collected as subjects completed the questionnaires. Next, the Hi-Lo test was performed, followed by the BHT tests and then, lastly, the FMS™ was performed. Reference Measures Biomechanical Dimension To determine if a subject had a biomechanical breathing problem, the Hi-Lo Breathing Assessment29 was utilized as the reference. The Hi-Lo is a manual assessment to determine if a subject is in a normal diaphragmatic breathing pattern or if they are in an abnormal pattern. It was performed in the sitting position with the tester standing or kneeling at the front and slightly to the side of the subject. The tester placed one hand on the subject’s sternum and one hand on their upper abdomen to determine whether thoracic or abdominal motion is dominant during breathing. Assessment for paradoxical breathing is also performed by determining if the abdomen moves in a direction opposite to the thorax during breathing; this is evident during inhalation if the abdomen moves toward the spine, and during exhalation if the abdomen moves in an

outward direction. The scoring process was as follows: Is the upper chest dominant? If yes scores as dysfunctional and stop, if no continue. Is the pattern paradoxal? If yes score as dysfunctional and stop, if no continue. Is diaphragm dominant? (greater volume and diaphragmatic movement is first), if yes score as functional, if no score as dysfunctional. The Hi-Lo test reliability has been reported by others as acceptable,23 and the researchers in this study achieved 88% agreement with a Kappa = .75 on 43 subjects assessed during data collection. Biochemical Dimension To determine if a subject had a biochemical breathing problem, capnography was utilized as the reference measure. Capnography is a measurement taken via nasal cannula to determine ETCO2. The average resting value over a three minute data collection period was utilized to obtain the measure, and the standard value of < 35 mmHg was utilized as the cut-off for dysfunction.24-26 The capnography unit (CapnoTrainer, Better Physiology Ttd. Boulder, CO, USA) was calibrated according to the manufacturer recommended procedure prior to each data collection session. Respiration rate in breaths per minute was calculated from the capnography data. Psychophysiological Dimension To address the psychophysiological dimension, two separate breathing questionnaires were administered. The Nijmegen Questionnaire is a 16-item questionnaire developed in the 1980’s to identify patients who have breathing dysfunction that emphasizes relationships with common diseases. A cut score of ≥ 22 on the Nijmegen was utilized to define DB.30 The Self-Evaluation of Breathing Questionnaire (SEBQ), Version 331 is a questionnaire that includes 25 questions to determine selfperception of breathing dysfunction. Test-retest reliability has been shown to be high32 and a cut score of ≥ 25 on the SEBQ was utilized to define DB for this study. The SEBQ is a new tool, and there is no established cut-score confirmed in the literature to define those with this dimension of breathing dysfunction. Expert opinion suggests a score of 25 as an appropriate cut-score. All subjects completed both questionnaires and scoring above the established cut-score on either questionnaire was used

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as the reference measure for the psychophysiological dimension. Screening Tests Clinical tests that the researchers hypothesized may be associated with DB were also performed. Tests administered included those that were most closely associated with DB from the current literature. Additionally, each test had to be easily obtained by a nonhealthcare provider so the screen could be employed in a fitness setting. Breath hold time (BHT) was measured by testing the functional residual capacity, also known as the controlled pause method which is a measure of how long a subject can hold their breath starting at the end of a normal exhale until first involuntary muscle activity was noted by the tester. This BHT test is described by Courtney and Cohen33 to be the most reproducible method because involuntary motion of the respiratory muscles has been found to be more of a consistent measure of breaking point of breath holding than the self-report of the sensation of the urge to breathe, which is an alternative method to assess BHT. The researches measured inter-tester reliability on BHT between two testers and found the ICC3,2 = 0.88 (0.78-0.93). BHT has been shown to be reduced in those with DB, and it has been suggested that reduced BHT may indicate problems in respiratory control that result in DB.33,34 The BHT test was performed with the subject in sitting. They were instructed to sit quietly and breathe normally, then, at the end of a normal exhalation, to pinch their nose and hold the breath. The time was started when the subject pinched the nose and was stopped at the first involuntary movement of the respiratory muscles or when the subject unplugged the nose, as determined by the tester. Respiration rate (RR) was measured in breaths per minute. Higher than normal RR have been shown to be associated with DB.22 The RR data was obtained from the capnography unit data output. Activity level was measured using a standard questionnaire. The questionnaire, similar to the Tegner Activity Scale, is scored from a high of 10 (competitive sports) to a low of 1 (sedentary). The questionnaire can be found in Appendix 1. It was hypothesized

that those with lower activity levels would be more likely to have DB. The FMS™ was used as a measure of movement dysfunction. Previous research has demonstrated that those scoring lower on the FMS™ (more dysfunctional movement) also had a greater tendency to demonstrate signs of DB.11 In the research, Bradley and Esformes demonstrated that subjects who scored lower on the FMS™ were more likely to demonstrate an abnormal biomechanical breathing pattern (upper chest breathing) and more likely to be hypocapnic, demonstrating significantly lower ETCO2 values. These findings were present both when the composite score with a cut point of ≤ 14 on the FMS™ was utilized to define movement dysfunction and when a “pass/fail” approach (pass = no 0’s and no 1’s, fail = any score of 0 or 1) was utilized to define movement dysfunction. The FMS™ is a reliable35-41 (ICC values ranging from 0.76-0.90 and Kappa values from 0.70-1.0) movement-screening tool created to rank basic movement patterns. The FMS™ includes seven movements: overhead deep squat, hurdle step, inline lunge, shoulder mobility, active straight leg raise, trunk stability pushup, and rotary stability. Each of these patterns is graded on a 0-3 ordinal scale where 0 represents pain with the movement, 1 represents dysfunctional movement, 2 represents acceptable movement, and 3 represents optimal movement. STATISTICAL METHODS The first step was to dichotomized subjects according to their performance on the reference tests for DB. Subjects who scored below the stated cut-score on one or more of the reference tests were classified as having DB, and those above the cut score on each of the reference tests were classified as having normal breathing. Next, the data were explored to help determine what index tests should be included as a screen for DB. One-way ANOVA’s were utilized to determine if there were any significant differences between subjects who were classified as DB compared to those who were not on the clinical tests and measures obtained to create the index test. The clinical tests and measures included activity level, breath hold time, respiration rate and the FMS™. Next, 2x2 contingency tables and routine diagnostic test statistics were utilized to test different combinations of the measures with the goal of identifying those measures

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that would yield the greatest sensitivity relative to an individual subject’s probability of being positive on any of the 3 dimensions of DB as described. RESULTS Five subjects demonstrated normal breathing, 13 failed at least one measure, 21 failed at least two, and 12 failed all three. There were no correlations between the three measures of DB.

Activity Level There was a difference in activity level between those who passed (6.78) and failed (4.81), p < 0.01, the Hi-Lo test. There was a difference in activity level between those who passed (5.53) and those who failed (4.25), p = 0.02, the questionnaires. No difference in activity level was found between those who were above or below the normative value for ETCO2 of 35 mmHg (p = 0.83) (Tables 1-3).

Table 1. Clinical tests results for biochemical dimension of dysfunctional breathing as deďŹ ned as a resting End-Tidal CO2 (ETCO2) < 35mmHg.

Table 2. Clinical tests results for biomechanical dimension of dysfunctional breathing (Hi-Lo Test).

Table 3. Clinical tests results for the breathing symptoms dimension of dysfunctional breathing as measured by the Self-Evaluation of Breathing Symptoms Questionnaire (SEBQ) >25 or Nijmegen Breathing Questionnaire >22.

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Table 4. Mean, standard deviation and ANOVA results between subjects in each dysfunctional breathing dimension(s) and clinical tests hypothesized to be associated dysfunctional breathing.

Breath Hold Time There was not a significant difference in BHT between those who passed (25.53 seconds) and failed (20.88 seconds) the Hi-Lo (p = 0.10). There were no significant differences in BHT or ETCO2 between those who passed or failed the questionnaires (Tables 1-3). Functional Movement There was a difference in composite FMS™ scores between those who passed (16.0) and failed (13.5) the Hi-Lo (p < 0.01). There was a difference in composite FMS™ scores between those who passed (14.41) and failed (13.5) the questionnaires (p = 0.03). No difference in composite FMS™ scores was found between those above or below the normative value for ETCO2 of 35 mmHg (p = 0.47) (Tables 1-3). When the FMS™ was considered from a pass/fail perspective (fail = any 1’s or 0’s), there was a difference in ETCO2 between those who passed (36.59 mmHg) and those who failed (33.87 mmHg) the FMS™ (p = 0.03). Respiration Rate There were no differences RR between subjects who passed or failed any of the measures of DB (Tables 1-3). Severity There were no significant differences in mean values of each of the clinical tests performed and severity of DB considering subjects that had no positive reference tests, n = 5, at least one positive test (n =

Table 5. Results from using Pass/Fail on the FMS™ only as a potential screen to predict those with dysfunctional breathing.

13), at least two positive tests (n = 21) and all three positive tests (n = 12) (Table 4). The only clinical test that related in some manner to all three dimensions of DB was the FMS™. Although a correlation exists between lower scores on the FMS™ and DB, when tested as a screen for DB using the FMS™ Pass/Fail criteria only, the results yielded a low sensitivity of 0.52 (Table 5). Because activity level had relationships with some aspects of DB, a ROC curve was utilized to determine if there was a meaningful cut-point that discriminated between those with and without DB. There was no clear cut-point with the AUC from the ROC curve = 0.44. Exploration of the data continued for trends and possible combinations of tests or questions that could provide the best clinical screen that captured those subjects who had 1, 2, or all 3 dimensions of DB.

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Because BHT of <20 seconds has been described in the literature as a clinical measure related to those with DB, it was tested alone as a possible screen at two different cut points. When using BHT alone with a 20 second cut-off the sensitivity was 0.54 (0.49-0.58) and specificity was 0.60 (0.18-0.92) (Table 6). Then the cut score of BHT at 25 seconds was assessed, and the sensitivity improved to 0.74 (0.69-0.77) (Table 7). The BHT cut score of 25 seconds improved the sensitivity but there were still a fairly high number of false negatives, 12 subjects that were above the cut-score on the BHT of 25 seconds but were still diagnosed by the reference as having at least one dimension of DB present. Next, the data from the questionnaires were analyzed to determine if adding in one or more questions could help to strengthen the proposed breathing screen. Each question from the questionnaires was investigated by identifying those questions that were most Table 6. Results from using only the breath hold test (BHT) <20 seconds as a potential screen to predict those with DB.

often scored at the higher levels of dysfunction. The SEBQ is scored on a four-level ordinal scale (0- never/ not true at all; 1- occasionally/a bit true; 2- frequentlymostly true; and 3- very frequently/very true) so any question from the SEBQ scored as a 2 or 3 was utilized. The Nijmegen is scored on a similar five-point ordinal scale but it is scaled 0-4 (0- Never, 1- Rare, 2- Sometimes, 3- Often, and 4- Very Often) so any question scored as a 3 or 4 was utilized. Frequency counts of those questions that subjects most often scored at these higher levels of dysfunction were calculated and it was determined that SEBQ questions #5 and #25 and Nijmegen questions #2 and #14 were the most important questions to ask to help to identify those who have some level of DB. Those subjects who answered at least one of the four questions at this higher level, did have a statistically significant relationship, Chi-Square = 0.03 (see Appendix 2). Because of this significant relationship, a mini-questionnaire was created that consisted of these four questions and added this to the 25 second BHT cut-off to see if the sensitivity improved with the addition of the questions. With the combination of the BHT cut-score of 25 and the mini-questionnaire as the reference test, the sensitivity increased to 0.89 (0.85-.093) with LR- = 0.18 and a specificity of 0.60 (0.18-0.92) with LR+ = 2.33 (Table 8). DISCUSSION In this study, four questions and a breath hold time test, used in combination, were found to be highly sensitive to identify those with some dimension of dysfunctional breathing. Only tests that could be performed by non-healthcare personnel were considered, to allow the screen to have utilization in fitness applications as well as the rehabilitation fields. When screening for a possible measureable disorder,

Table 7. Results from using the breath hold time (BHT) of < 25 as a potential screen to predict those with dysfunctional breathing.

Table 8. Results for the ďŹ nal screen for dysfunctional breathing including breath hold time of <25 seconds and/or any one question positive from the mini-questionnaire.

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the tool used should be highly sensitive, that is, when the screen is negative you are fairly confident that the disorder is not present. It is important to realize when the results of a highly sensitive screen are positive, it may not confirm the disorder, rather, it suggests further testing or assessment is warranted. It is recommended that in those individuals, either fitness or rehabilitation clients who are positive on this screen, further testing and assessment for DB be performed by a qualified healthcare provider.

if any, are present. These data are in agreement with Bradley11 as well where they showed a relationship between two of the three dimensions of DB but that all three were not closely correlated, again suggesting the need to assess for all three dimensions. The current study did show a relationship between AL and two of the three dimensions, biomechanical and breathing symptoms. The BHT was not significantly correlated with any dimension of DB from a univariate perspective, but did contribute to the final screen.

There is no standardized and well-accepted clinical assessment for DB. A comprehensive review by CliftonSmith and Rowley42 stated that the lack of a definitive assessment tool makes diagnosing breathing disorders difficult. They suggest that a comprehensive assessment should include a wide variety of measures including an accurate medical history and understanding of the subjects musculoskeletal status, a visual and hands on assessment of breathing and muscle status, self-reported questionnaires, a breathing hold time, peak expiratory flow rate and pulse oximetry. Additionally, spirometry and capnography may be used if available. As the awareness of DB grows there will be a need to standardize assessment tools for both rehabilitation and fitness settings.

The results from the current study were similar to Bradley11 in that we both showed a relationship between being a predominately thoracic breather and having poor movement. While Bradley reported a correlation between lower ETCO2 and lower FMS™ scores, the data from this study was analyzed differently. When the FMS™ was considered as a pass/fail variable, there was a relationship with lower ETCO2 and failing the FMS™, but when the FMS™ was analyzed as a continuous variable there were not differences in FMS™ scores between those above or below the normative value for ETCO2 of 35 mmHg (p = 0.47). Because the FMS™ mean scores for most populations have a small range, normally between 13-15 on the composite score, and the composite score in and of itself may not be that useful, the recommendation is to consider FMS™ information on a pass/ fail basis as much as possible. One can conclude an individual failing the FMS™ is more likely to be a thoracic breather and have a lower ETCO2. Additionally, scoring lower on the FMS™ from a composite perspective will more likely be associated with failing the SEBQ, demonstrating the presence of breathing symptoms. But, taken together, using only the FMS™ score to screen for DB yielded a sensitivity of only 0.52 and, therefore, is not recommended. In this case, although the FMS™ had a statistical relationship with DB, it yielded a low sensitivity because there were 22 subjects who passed the FMS™, but did have some dimension of DB. These were false negatives that lowered the sensitivity. From these data, the FMS™ alone should not be used as a screen for breathing.

Several authors have demonstrated that breathing re-training programs are effective,43-45 but the outcome tools utilized and the populations studied vary widely making it challenging to become widely accepted in the medical literature. It would be ideal to standardize a breathing screen, tests, and an assessment to better understand which intervention approach is most effective for each type of DB. To do this will require an approach similar to the treatment based classification system utilized for patients with acute low back pain where clinically captured data allows for the creation of diagnostic categories.46,47 Establishing diagnostic categories of DB may serve to clarify the complex nature DB and help to standardize future research efforts. Data from this study are similar to those of Courtney et al21 who demonstrated that DB has three distinct dimensions and that they often do not correlate well, suggesting a need to screen for the condition of DB overall and then have further assessments that can be performed to identify which dimension(s) of DB,

While there was a univariate trend in lower BHT being related to the biomechanical dimension, when BHT was applied with a cut score of 25 seconds, the sensitivity strengthened substantially; along with adding in the mini-questionnaire, all three

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dimensions of DB were captured. A breath hold time of 20 seconds has been proposed as a cut-off to identify those with hyperventilation syndrome. Jack et al34 reported a mean BHT of 20 (SD 12) seconds in individuals with known breathing dysfunction which compares closely to the mean of 21.9 (SD 9.3) seconds from the current study in those who were considered positive on any one or more of the reference tests used for DB. A limitation to this study is that the sample size is considered small to establish a new screening tool. The next step is to perform a validation study of the breathing screen with another sample of subjects. Additionally, only five subjects passed all the tests performed for DB indicating a high incidence (90%) of DB in this population, which is higher than expected. The threshold of 25 seconds is challenging to achieve and it will take further research in more diverse samples to determine if this threshold can be validated. Also, the activity level questionnaire utilized in the current research is a modified version of the Tegner Activity Scale.48 Although similar, this tool has not been validated in the literature to date. CONCLUSION Easily obtained clinical measures of BHT and four questions can be utilized to screen for the presence of DB. If the screen is passed, there is a 89% chance that DB is not present. If the screen is failed, further assessment is recommended to determine if DB breathing is present and if so, which dimension is affected. Additionally, these findings help to validate previous findings that link movement and breathing dysfunction. REFERENCES 1. Courtney R, van Dixhoorn J, Greenwood KM, et al. Medically unexplained dyspnea: partly moderated by dysfunctional (thoracic dominant) breathing pattern. J Asthma. 2011;48(3):259-265. 2. Thomas M, McKinley RK, Freeman E, et al. Prevalence of dysfunctional breathing in patients treated for asthma in primary care: cross sectional survey. BMJ. 2001;322(7294):1098-1100. 3. Lowhagen O. [Asthma--a disease difficult to define. Patients can receive correct treatment by means of differential diagnosis criteria]. Lakartidningen. 2005;102(50):3872-3873, 3875-3878. 4. Pryor JA PSC. Physiotherapy for Respiratoryand Cardiac Problems. Edinburgh, UK: Livingstone; 2002.

5. Kolar P, Sulc J, Kyncl M, et al. Postural function of the diaphragm in persons with and without chronic low back pain. J Orthop Sports Phys Ther. 2012;42(4):352-362. 6. Smith MD, Russell A, Hodges PW. Disorders of breathing and continence have a stronger association with back pain than obesity and physical activity. Aust J Physiother. 2006;52(1):11-16. 7. McLaughlin L, Goldsmith CH, Coleman K. Breathing evaluation and retraining as an adjunct to manual therapy. Man Ther. 2011;16(1):51-52. 8. Hagman C, Janson C, Emtner M. A comparison between patients with dysfunctional breathing and patients with asthma. Clin Respir J. 2008;2(2):86-91. 9. Whittaker JL. Ultrasound imaging of the lateral abdominal wall muscles in individuals with lumbopelvic pain and signs of concurrent hypocapnia. Man Ther. 2008;13(5):404-410. 10. Courtney R, Cohen M, van Dixhoorn J. Relationship between dysfunctional breathing patterns and ability to achieve target heart rate variability with features of “coherence” during biofeedback. Altern Ther Health Med. 2011;17(3):38-44. 11. Bradley H, Esformes J. Breathing pattern disorders and functional movement. Int J Sports Phys Ther. 2014;9(1):28-39. 12. Lewit K. Relation of faulty respiration to posture, with clinical implications. J Am Osteopath Assoc. 1980;79(8):525-529. 13. Hodges PW, Sapsford R, Pengel LH. Postural and respiratory functions of the pelvic floor muscles. Neurourol Urodyn. 2007;26(3):362-371. 14. Kiesel KB, Knox T. Core stability for the running athlete. In: O’Connor F, Wilde R, eds. Running Medicine. 2nd ed. Montaray, CA: Healthy Learning; 2014:1801-1825. 15. Kiesel K, Burton S, Cook E. Mobility screening for the core. Athl Ther Today. 2004;9(5):42-45. 16. Hodges PW, Gandevia SC. Changes in intraabdominal pressure during postural and respiratory activation of the human diaphragm. J Appl Physiol (1985). 2000;89(3):967-976. 17. Richardson CA, Jull GA, Hodges PW, et al. Therapeutic Exercise for Spinal Segmental Stabilization in Low Back Pain; Scientific Basis and Clinical Approach. Edinburgh: Churchill Livingstone; 1999. 18. Zazulak BT, Hewett TE, Reeves NP, et al. Deficits in neuromuscular control of the trunk predict knee injury risk: a prospective biomechanical-epidemiologic study. Am J Sports Med. 2007;35(7):1123-1130. 19. Peate WF, Bates G, Lunda K, et al. Core strength: a new model for injury prediction and prevention. J Occup Med Toxicol. 2007;2:3.

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20. O’Sullivan PB, Grahamslaw KM, Kendell M, et al. The effect of different standing and sitting postures on trunk muscle activity in a pain-free population. Spine (Phila Pa 1976). 2002;27(11):1238-1244. 21. Courtney R, Greenwood KM, Cohen M. Relationships between measures of dysfunctional breathing in a population with concerns about their breathing. J Bodyw Mov Ther. 2011;15(1):24-34. 22. Chaitow L BD, Gilbert C. Multidisciplinary Approaches to Breathing Pattern Disorders. London, UK: Churchill Livingstone; 2002. 23. Roussel NA, Nijs J, Truijen S, et al. Low back pain: clinimetric properties of the Trendelenburg test, active straight leg raise test, and breathing pattern during active straight leg raising. J Manipulative Physiol Ther. 2007;30(4):270-278. 24. Gardner WN. The pathophysiology of hyperventilation disorders. Chest. 1996;109(2):516534. 25. Miner JR, Heegaard W, Plummer D. End-tidal carbon dioxide monitoring during procedural sedation. Acad Emerg Med. 2002;9(4):275-280. 26. Levitsky M. Pulmonary Physiology. New York, NY:McGraw Hill; 1995. 27. van Dixhoorn J, Duivenvoorden HJ. Efficacy of Nijmegen Questionnaire in recognition of the hyperventilation syndrome. J Psychosom Res. 1985;29(2):199-206. 28. Mosby’s Medical Dictionary. 9th ed: Elsevier; 2009. 29. Courtney R, Cohen M, Reece J. Comparison of the Manual Assessment of Respiratory Motion (MARM) and the hi lo breathing assessment in determining a simulated breathing pattern. Int J Osteopath Med. 2009;12(3):86-91. 30. Vansteenkiste J, Rochette F, Demedts M. Diagnostic tests of hyperventilation syndrome. Eur Respir J. 1991;4(4):393-399. 31. Courtney R, Greenwood, KM. Preliminary investigation of a measure of dysfunctional breathing symptoms: the Self Evaluation of Breathing Questionnaire (SEBQ). Int J Osteopath Med. 2009;12(4):121-127. 32. Mitchell AJ, Bacon CJ, Moran RW. Reliability and determinants of Self-Evaluation of Breathing Questionnaire (SEBQ) score: a symptoms-based measure of dysfunctional breathing. Appl Psychophysiol Biofeedback. 2016;41(1):111-120. 33. Courtney R, Cohen M. Investigating the claims of Konstantin Buteyko, M.D., Ph.D.: the relationship of breath holding time to end tidal CO2 and other proposed measures of dysfunctional breathing. J Altern Complement Med. 2008;14(2):115-123.

34. Jack S, Rossiter HB, Warburton CJ, et al. Behavioral influences and physiological indices of ventilatory control in subjects with idiopathic hyperventilation. Behav Modif. 2003;27(5):637-652. 35. Gulgin H, B. H. The Functional Movement Screening (FMS)™: an inter-rater reliability study between raters of varied experience. Int J Sports Phys Ther. 2014;9(1):14-20. 36. Smith C, Chimera N, Wright N, et al. Interrater and intrarater reliability of the Functional Movement Screen. J Strength Cond Res. 2013;27(4):982-987. 37. Gribble PA, Brigle J, Pietrosimone BG, et al. Intrarater reliability of the Functional Movement Screen. J Strength Cond Res. 2013;27(4):978-981. 38. Teyhen DS, Shaffer SW, Lorenson CL, et al. The Functional Movement Screen: a reliability study. J Orthop Sports Phys Ther. 2012;42(6):530-540. 39. Onate JA, Dewey T, Kollock RO, et al. Real-time intersession and interrater reliability of the Functional Movement Screen. J Strength Cond Res. 2012;26(2):408-415. 40. Minick KI, Kiesel KB, Burton L, et al. Interrater reliability of the Functional Movement Screen. J Strength Cond Res. 2010;24(2):479-486. 41. Frohm A, Heijne A, Kowalski J, et al. A nine-test screening battery for athletes: a reliability study. Scand J Med Sci Sports. 2011;22(3):306-315. 42. CliftonSmith T, Rowley J. Breathing pattern disorders and physiotherapy: inspiration for our profession. Phys Ther Rev. 2011;16(1):75-86. 43. Holloway E, Ram FS. Breathing exercises for asthma. Cochrane Database Syst Rev. 2004(1):CD001277. 44. Hagman C, Janson C, Emtner M. Breathing retraining - a five-year follow-up of patients with dysfunctional breathing. Respir Med. 2011;105(8):1153-1159. 45. Jones M, Troup F, Nugus J, et al. Does manual therapy provide additional benefit to breathing retraining in the management of dysfunctional breathing? A randomised controlled trial. Disabil Rehabil. 2014;37(9):763-770. 46. Alrwaily M, Timko M, Schneider M, et al. Treatmentbased classification system for low back pain: revision and update. Phys Ther. 2016;96(7):1057-1066. 47. Fritz JM, Cleland JA, Childs JD. Subgrouping patients with low back pain: evolution of a classification approach to physical therapy. J Orthop Sports Phys Ther. 2007;37(6):290-302. 48. Briggs KK, Lysholm J, Tegner Y, et al. The reliability, validity, and responsiveness of the Lysholm score and Tegner activity scale for anterior cruciate ligament injuries of the knee: 25 years later. Am J Sports Med. 2009;37(5):890-897.

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Appendix 1. Activity rating scale.

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Appendix 2

Tabulations of how the mini-questionnaire was developed showing the questions with the highest frequency counts of subjects who scored either of the 2 higher levels of dysfunction. Each question is scored on a fourpoint ordinal scale from each of the self reported questionnaires utilized. The Nijmegen is scored on a five-point ordinal scale from 0-4 (0- Never, 1- Rare, 2- Sometimes, 3- Often, and 4- Very Often) so any question scored as a 3 or 4 was utilized. These 2 questions from the Nijmegen were the most frequently scored at the high end of dysfunction (a score of 3 or 4): Do you feel tense? 10 subjects Do you feel a cold sensation in your hands or feet?

14 subjects

The SEBQ is scored on a 4-point ordinal scale from 0-3. (0- never/not true at all, 1- occasionally/a bit true, 2frequently-mostly true, and, 3- very frequently/very true) so any score of 2 or 3 was utilized. These two questions from the SEBQ were the most frequently scored at the high end of dysfunction (a score of 2 or 3): Do you notice yourself yawning?

8 subjects

Do you notice breathing through your mouth at night?

8 subjects

Below is the 2 x 2 table used to calculate the Chi Square demonstrating a significant difference between frequency of subjects scoring the four questions and presence of dysfunctional breathing.

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IJSPT

ORIGINAL RESEARCH

SPORTS PHYSICAL THERAPY CURRICULA IN PHYSICAL THERAPIST PROFESSIONAL DEGREE PROGRAMS Edward P. Mulligan, PT, DPT, SCS, OCS, ATC1 Julie DeVahl, PT, DPT, OCS1

ABSTRACT Background: The specialty niche of sports physical therapy has grown at a significant rate over the past 40 years. Despite this growth there is little information or direction from the physical therapy education accreditation body or professional association to guide academic programs on the interest or necessity of this type of practice content in physical therapy professional degree programs. Purpose: The purpose of this survey study is to report on the prevalence, attitudes, barriers, resources, and faculty expertise in providing required or elective sports physical therapy course work. Study Design: Cross-sectional descriptive survey Methods: A 57-item questionnaire with branching logic was distributed via a web-based electronic data capture tool to survey all Commission on Accreditation for Physical Therapy Education (CAPTE) accredited and candidate schools in the United States. Response data was analyzed to describe typical educational program profiles, faculty demographics, and correlational factors consistent with the presence or absence of specific sports physical therapy curricular content. Results: Thirty one percent of the schools responded to the survey and the program demographics were consistent with all currently accredited schools in regards to their geography, Carnegie classification, and faculty and student size. Forty three percent of programs offered a required or elective course distinct to the practice of sports physical therapy. Descriptive information regarding the sequencing, curricular make-up, resources, and assessment of content competence is reported. The odds of providing this content nearly doubles for programs that have faculty with sports clinical specialist credentials, accredited sports residency curriculums, or state practice acts that allow sports venue coverage. Conclusions: This survey provides an initial overview of sports physical therapy educational efforts in professional physical therapy degree programs. The data can used to spur further discussion on the necessity, structure, and implementation of education content that is inherent to a growing specialty practice in the physical therapy profession. Level of Evidence: 4, Cross-sectional descriptive survey design Key words: Accreditation, clinical specialization, entry-level education, sports physical therapy

1

UT Southwestern School of Health Professions, Dallas, TX, USA

Acknowledgments: The authors would like to acknowledge the efforts of the Katie Lynch, PT, DPT, ATC, a sports physical therapy resident at the time of the study, for her assistance with the development of the survey tool. We declare that we have no conicts of interest in the authorship or publication of this contribution.

CORRESPONDING AUTHOR Edward P. Mulligan UT Southwestern Medical Center School of Health Professions 6011 Harry Hines Blvd Dallas, TX 75235 E-mail: ed.mulligan@utsouthwestern.edu

The International Journal of Sports Physical Therapy | Volume 12, Number 5 | October 2017 | Page 787 DOI: 10.16603/ijspt20170787

INTRODUCTION Sports physical therapy is a specialized subset of physical therapy practice that focuses on the health care management of the physically-active individual that has been injured in or aspires to return to athletic endeavors.1 The sports physical therapist establishes a customized plan of injury prevention, injury management, or performance enhancement in order to enable or maximize the athlete’s participation in sporting activities. Additionally, sports physical therapists have important administrative, educational, and ethical responsibilities to ensure the safety and well-being of the athlete. Performance of these responsibilities requires the sports physical therapist to capably communicate with athletes, coaches, parents, administrators, and other healthcare professionals.1-3 Since the inception of the sports physical therapy section in 1973 the interest in management of athletic health care issues has grown at a significant rate in the physical therapy profession. The Sports Physical Therapy Section (SPTS) of the American Physical Therapy Association (APTA), a component member of the APTA, exists to provide a forum in which physical therapists interested in sports-related injuries can share ideas and learn about the unique skills and knowledge that define this area of specialty practice.4 Currently there are over 8,000 SPTS members (1,500 of which are students) and 1,914 clinicians have been certified as sports clinical specialists by the American Board of Physical Therapy Specialties (ABPTS) since its inception approximately 30 years ago. Many students become interested in a physical therapy career based on their interaction with sports physical therapists during their athletic career. Sports certified specialists were often competitive athletes in their youth (96%) and currently maintain a physically active lifestyle by exercising at least twice per week (97%).5-6 Additionally, during the 2014-2105 application cycle there were 165 qualified applicants who applied for 81 sports residency positions at 34 accredited programs, indicating that further training and specialization in sports physical therapy is of high interest to clinicians in this competitive physical therapy discipline.7 Even though there seems to be an emerging need and interest for this area of practice, the Commission on Accreditation for Physical Therapy Education (CAPTE) is

silent on the inclusion of curricular content specific to the area of sports physical therapy. Despite this seemingly high interest in sports physical therapy, the authors are unaware of any published studies that describe education efforts or competence criteria for entry level physical therapist professional preparation programs in the United States (U.S.) for sports physical therapy content. Additionally, the authors are unaware of any publications that would assist a program in developing a sports physical therapy curriculum independent of the ABPTS’s description of sports physical therapy practice. Unfortunately, this ABPTS document is intended to describe advanced specialty practice and goes beyond entry-level minimal competence. The purpose of this survey study is to report on the prevalence, attitudes, barriers, resources, and faculty expertise in providing required or elective sports physical therapy course work. Specific aims are to report the prevalence of programs teaching this content, attitudes or barriers to providing the content, and details regarding the curricular structure, program resources, and faculty expertise that is found at programs that are providing required or elective sports physical therapy course work. These survey results can serve as a curricular benchmark for the profession and spur further discussion on the need, means, obstacles, and benefits to developing sports physical therapy curricula in physical therapy professional degree programs. METHODS Tool Development The model for our survey was based on previous instruments developed to investigate the content and prevalence of curricula to teach manipulative therapy and diagnostic and procedural imaging in physical therapist professional degree programs based in the U.S.7-10 The broad categories for data capture on the survey included 1) physical therapist program and faculty representative respondent demographics, 2) descriptive information (content, resources, assessment methods, etc.) regarding the program curriculum, and 3) opinions regarding the need and appropriateness of sports physical therapy education in accredited programs. Three physical therapists with unique insights and experiences for

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teaching content unique to sports physical therapy content collaborated to draft the original survey tool. These developers included two faculty members with extensive experience in the practice of sports physical therapy and curricular design. The remaining contributor was a dual licensed sports physical therapist resident with one year of experience in both physical therapy and athletic training who reviewed this survey tool and provided feedback. The initial draft was piloted with six physical therapists with known interest and experience in providing sports physical therapy education. Critique regarding the survey’s content, organization, and readability enhanced content validity. Based on the collective input from these experts the survey tool was modified and finalized for distribution. The final data collection instrument is a 57-item questionnaire with branching logic based on the respondent’s answer as to whether or not their institution provided specific curricular content relevant to the practice of sports physical therapy. Programs without sports physical therapy coursework provided input on why this content was not included in their curriculum and what future plans they may have for addition of this content. Programs that offer sports physical therapy content provided information regarding their pedagogical structure, curriculum faculty, and program resources by responding to closed-ended, dichotomous or ordinal-valued questions. All programs provided demographics and the background and training of the individual responding to the survey on behalf of their institution. Participants All physical therapist professional degree programs recognized by CAPTE as accredited (n = 219) or candidate (n = 22) were queried for input. The survey invitation was sent via email to the contact addresses listed on the APTA’s web site. If the email address was not specific to a faculty member’s name, the school’s web site was searched for a faculty recipient who appeared to be responsible for orthopedic and/ or sports-related academic content. In all instances, the cover letter directed the recipient to forward the survey request to the faculty member most familiar with topics related to sports physical therapy. Based on a 95% confidence level it was calculated that at

least 69 responses were needed from the 241 schools to bring the margin of error to within + 10%. Survey Administration Study data was collected and managed using REDCap electronic data capture tools hosted at UT Southwestern Medical Center in Dallas, TX. REDCap (Research Electronic Data Capture, CTSA NIH Grant UL1TR001105) is a secure, web-based application designed to support data capture for research studies, providing: 1) an intuitive interface for validated data entry, 2) audit trails for tracking data manipulation and export procedures, 3) automated export procedures for seamless data downloads to common statistical packages, and 4) procedures for importing data from external sources. The Institutional Review Board at the University of Texas Southwestern Medical Center reviewed and provided exempt approval of the study protocol. The study cover letter described the study’s purpose, emphasized anonymity through aggregate-only reporting, and stated that voluntary consent was designated by responding to the survey link. After the initial email was extended, follow-up requests were sent at one, two and four weeks. Further requests for participation were stopped as the response rate plateaued over the next week. The survey was open for response during a five-week interval in January and February of 2017. Data Analysis Data collected in RED-Cap was imported into an Excel (Microsoft Corporation, Redmond, WA) spreadsheet for statistical analysis. Descriptive statistics were calculated to describe educational program profiles and responding faculty demographics. An on-line program at www.vassarstats.net was used for correlational analysis (Pearson, Point Biserial, and Phi Coefficient) and non-parametric MannWhitney analysis of the differences between schools with and without sports physical therapy education curricula. RESULTS Of the 241 CAPTE recognized physical therapist programs in the U.S. 74 (31%) responded to our survey. This included 66 of the 219 (30%) accredited and 8 of the 22 (36%) of the developing programs.

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Forty-three (61%) of the programs that responded were classified as public universities, 18 (26%) were private not-for-profit institutions, and the remaining 9 (13%) programs were private for-profit programs. Schools from 32 of the 47 states with accredited physical therapy programs are represented in the results. All states with more than three programs have at least one school included in the analysis. (Table 1) One hundred percent of the faculty representatives responding on behalf of their program were licensed physical therapists. (Table 2) The mean program length (34 months), number of students/class (44), total number of faculty (16), and total number of faculty with clinical specialist credentials were nearly identical to the most current (2015-16) aggregate program data fact sheet provided by CAPTE indicating that the current sample was representative of the population as a whole.11 The mean number of certified clinical specialists for the respondent programs was 7.5 with over half of those being either orthopedic or sports specialists (3.5 and 1.0 respectively). Additionally, respondent programs averaged

approximately one faculty member who was certified as an athletic trainer. Eighty percent of the respondents indicated that there was an intercollegiate athletic program on their campus with the majority competing at the Division I level. Of those programs that had an athletic program on or near campus, 28% of the programs had a faculty member(s) that provided team coverage or care of athletes on campus or in their community. (Table 1) Sports Physical Therapy Curricula Thirty-two (43%) of the programs reported they had a distinct course unique to the roles, skills, and knowledge of sports physical therapy included in their curriculum. Of those schools offering sports physical therapy education, 35% of the programs required this course while 65% offered the content as an optional elective. Twenty-seven (27%) of the programs provided coursework that specifically prepared students for certification as a strength and conditioning specialist. Of the 32 programs that

Table 1. Demographics of Respondent Physical Therapy Programs (n = 74)

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Table 2. Demographic description of faculty members responding to the survey

offered sports physical therapy classes, 56% offered strength and conditioning content. Similarly, of the 20 programs that provided strength and conditioning content, 70% also offered sports physical therapy coursework. The majority of sports physical therapy education is provided towards the end of the student’s educational tenure with 59% of the programs providing course work in the final year of learning while 38% of programs provided the content during the second year of the program. For those programs that provided sports physical therapy course, the mean number of contact hours was 23 with a range of 4 to 60. Fifty five percent of class time was categorized as lecture, 39% as laboratory, 4% as independent study, and 2% as field observation. These values would suggest that the typical sports physical therapy class is a one credit hour course. (Table 3) Curricular content emphasized sports-specific injury evaluation, biomechanics, rehabilitation and prevention strategies, and return to activity testing. Knowledge and skill areas embedded within the description of sports physical therapy practice that received less instructional emphasis included environmental influences, athletic protective equipment, weight and nutritional considerations, injury psychology, and sleep hygiene. Unique patient subsets of the athletic population that were emphasized

in the curriculum included the “female” and “overhead” athlete. Conversely, education regarding the management of the “disabled” athlete was a much lower content priority. (Table 4) The most common learning supplement used in the sports physical therapy curricula were selected journal articles with 87% of programs reporting that this resource was made available to students. Less frequent resources to accompany class activities were textbooks (32%), internet-based web content (29%), and materials provided by the SPTS of the APTA (29%). Competence of sports physical therapy concepts were evaluated in a variety of manners but written examination was the most common method of assessment (77%). Project submission was used in 53% of programs. Practical examinations were administered in 47% of programs. Less frequent methods of assessing student’s acquisition of sports physical therapy knowledge and skills were simulation exams (10%) and live athlete assessments (3%). There were only a very small percentage of cases where student assessment was not required in the course or that credit was given simply for participation and/or observational time. The most common reason cited for not providing curricular content specific to sports physical therapy was an overall lack of time in the curriculum (52%).

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Table 3. Contact Hours for Teaching Sports Physical Therapy (n = 32)

Thirty eight percent of the programs did not feel this content was a curricular priority and 29% did not consider this competence to be an entry-level skill. Infrequent reasons for not providing sports physical therapy class work was a lack of funding to hire qualified faculty (12%), inadequate published criteria to guide the curriculum development (7%), or concerns about increasing tuition burden on the students (7%). Sports Physical Therapy Curriculum Faculty For programs that provided a sports physical therapy course the curriculum coordinator was a full-time core faculty member 80% of the time. If utilized, the most common additional faculty contributors to the course were guest lecturers (60%) and adjunct faculty (40%). The mean instructor to student teaching ratio for lab based activities was 13.9 + 7.5 with approximately equal number of programs reporting this ratio as higher, equal, or lower than other coursework in the curriculum. Factors that Inuence Inclusion of Sports Physical Therapy Curricula There was no difference in the presence of sports physical therapy course based on program accredi-

tation status (p = 0.83); program length (p = 0.22), number of students/class (p = 0.78), number of faculty (p= 0.58), number of faculty that are certified orthopedic clinical specialists, collegiate athletic team availability near campus (p = 0.67), or number of faculty that were also certified as athletic trainers (p = 0.29). Program demographic factors that did have a significant difference and fair correlation with the presence of a sports physical therapy curriculum were state practice acts that allowed venue coverage (φ = 0.28, p = 0.04) and the number of faculty that have a sports clinical specialist certification (rpb = 0.35, p = 0.002). The odds of a program having a sports physical therapy course nearly doubles (OR = 1.75, 95 CI 0.81-3.76) with the presence of a sports clinical specialist on faculty. Of the 14 American Board of Residency and Fellowship Education accredited sports residencies at the time of the survey that were sponsored by an academic institution, nine responded to the survey. Of these nine, 78% (7) provided an optional or specific sports physical therapy course. There was also a fair correlation between programs that offered a sports physical therapy curriculum and coursework that would specifically prepare the

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Table 4. Inter-rater Reliability Criterion Checklist Scoring.

students for a strength and conditioning specialist certification (CSCS) (␾ = +0.33, p = 0.01). DISCUSSION To the authors’ knowledge these findings provide the first published description of sports physical therapy curricula in U.S. professional degree education programs. Forty three percent of the responding programs provide a specific course for teaching sports physical therapy concepts with another 15% of the programs planning to introduce sports physical therapy content into their curriculum in the next two to three years. By far the two most common reasons for not providing a sports physical therapy course were a “lack of time” in the curriculum (52%) and the content was not considered a curricular priority for inclusion (38%). Less common reasons for not

providing sports physical course work were lack of qualified faculty, lack of funding, lack of published guidance to develop a curriculum, or concerns about additional tuition costs for the students. It seems resources are available to provide this education but finite time limitations and/or other curricular priorities prohibit universal instruction in this area of physical therapy practice. Programs that did not provide a specific course in sports physical therapy were asked to estimate the amount of time that was devoted to teaching sports injury prevention, evaluation, treatment, and performance enhancement specific to the athlete. The mean aggregate time reported was 74 hours suggesting that while there was not a specific course offered in the program, the theme of sports physical therapy

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was a curricular thread as this total represents approximately 3-4 hours of educational credit. Much like programs that provided a specific sports physical therapy course the majority of time dedicated to the topic of sports physical therapy concerned the evaluation and management of sport-specific injuries (77% of time). The assumption being that this time was an extension of the broader musculoskeletal perspectives taught in orthopedic course work. A much smaller proportion of time was devoted to skill and knowledge areas that are truly unique to the specialty practice of sports physical therapy. The remaining 23% of time covered athletic injury prevention (9%), performance enhancement (7%), care for the disabled athlete (4%), and acute, “sideline” care (3%). Only 52% of programs that did provide a sports physical therapy course actually included instruction and training in emergency care of life-threatening athletic injuries such as spinal cord trauma, cardiac arrest, heat stroke, internal organ injury, or rhabdomyolysis. This relative lack of focus on venue coverage and emergency responder skills justifies the requirement of emergency medical responder training or experience as an athletic trainer to apply for a sports physical therapy residency position. This type of acute care management knowledge is also important in a much broader context as all physical therapists may encounter life-threatening situations in their occupational and ordinary activities of life in which emergency management skills may be required. Variability in curricular design was found amongst programs that provided a sports physical therapy course. Class time for lecture and laboratory basedactivities averaged 21 hours/semester but ranged from 1-30 hours with a large standard deviation of instructional exposure time (8.5 hours). Suggestions for improving the students’ application of sports physical therapy knowledge and skill also varied. The most common recommendation for instructional improvement was increased field/venue exposure for observation (86%). While this method of teaching was not emphasized in many curriculums, it was a significant predictor of a program offering a specific sports physical course (φ = 0.28, p = 0.04). Other suggestions for curricular improvement from academic programs included increased lab time (55%), increased lecture time (31%), and involvement of other health care providers (sports

physicians 31%; athletic trainers 20%) for instruction. These responses strengthen the rationale for increased multi-disciplinary field exposure for students to strengthen their familiarity with injuries prevalent to athletic competition. It is commonly thought that exposure breeds familiarity and it often takes a significant investment of time to be present when injuries actually occur. There were also a wide variety of mechanisms used to assess student understanding of content. There was an inconsistent utilization of written and practical exams across programs. Less than half of the programs conducted a practical examination to assess psychomotor skills and even fewer employed simulation testing. Projects or credit for observational time were often used to determine grades and/or class credit. The utilization of written exams is consistent with the current method of testing for both sports physical therapy and athletic training certification which have remarkably similar areas of competency domains.12 See Figure 1. Despite these similarities is it unknown if this current curricular content or the methods of competency assessment adequately prepare the student for advanced certifications or differentiate their skill and knowledge from other licensed health care providers. Methods and timing of curricular content delivery seemed more consistent across programs. Full-time faculty members typically coordinated the course and the instructor to student ratio did not differ significantly from other lab-based coursework in the curriculum. There was also a consensus that the curriculum should focus on sports specific injuries and return to play criteria in the female and overhead athlete. Supplementary learning material was largely provided through journal article resources. Twenty three percent of programs did not use any supplementary resources independent of course lecture handouts. Virtually all programs that provide a sports physical therapy course do so later in the curriculum with 30 of the 32 programs waiting until the second or third year of the curriculum. The delayed introduction of this content may suggest that the mastery of this specialty niche requires foundational knowledge and/or familiarity with patient management strategies introduced earlier in physical therapy curricula.

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Figure 1. Athletic Training Competency Exam Content and Sports Physical Therapy Comparisons

Surprisingly, a relatively small percent of programs utilize SPTS resources and this may be an avenue for the SPTS to serve the educational degree programs in a manner similar to the Orthopedic Section’s Imaging and Foot/Ankle Special Interest Groups, which have provided imaging education manuals and resource lists.13-14 Similarly, many specialty sections and academies, including the Clinical Electrophysiology and Wound Care, Geriatrics, Neurology, Pediatrics, and Women’s Health of the APTA, have provided compendiums and resources to assist professional-level physical therapist educators with curricular development and delivery guidelines and materials.15 Since there are no current guideline requirements or recommendations for sports physical therapy from the APTA, the Normative Model of Physical Therapist Professional Education, or in CAPTE’s evaluative criteria this type of document could help establish recommendations on the instructional breadth and depth of this content. The SPTS could recruit professional degree and residency program curriculum coordinators to develop resources, clarify legal implications, establish basic curricular content, identify teaching resources, and develop standards of competency assessment that would benefit programs in need of curricular assistance. The results of this survey indicate that programs generally have the personnel and resources available to implement this sports physical therapy curriculum.

Unfortunately, it seems that programs typically have more assets than time to address every specialty practice area relevant to the physical therapy profession. Since all programs may not be able to offer every specialty content areas it may behoove some programs to selectively offer content in which they do have the appropriate faculty, expertise, and facilities. Perhaps programs with sports physical therapy residency programs or clinical specialist faculty with convenient and legal access to athletic venues could be the ideal environment for instructional exposure to sports physical therapy content. In fact, this combination of resources could serve to distinguish one educational program from another and entice potential program applicants. Future areas of study could include further clarification on how or if “orthopedic” and “sports” physical therapy content overlap in CAPTE accredited professional degree programs. Both specialty areas have strong orthopedic components but one specialty’s construct is based on the musculoskeletal physiological system and the other is focused on health care issues specific to an athletic activity environment, avocational, or recreational pursuits.1,17 Content differentiation may help programs decide if sports physical therapy is an advanced level of proficiency that builds upon general orthopedic skills and knowledge or if it should be considered foundational knowledge that is required of all entry-level providers.

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Also, worthy of further study is how program outcomes are affected by the inclusion or exclusion of a specific course on sports physical therapy. Dependent variables that could be evaluated may include the influence of graduate employment setting selection, the impact on sports physical therapy residency/fellowship application and acceptance frequency, or the graduates’ success rate on specialty certification examinations.

necessity, structure, and implementation of educational content that is inherent to a popular specialty area of practice in the profession. This data can be used to standardize some aspects of content delivery and provide benchmarks for further assessment of the value of teaching sports physical therapy to students as they prepare for a career in the profession.

Despite the array of noteworthy findings, the present study is not without limitations. While the survey concluded with an open-ended question soliciting additional input on any relevant concern it is possible that pertinent information germane to the sports physical therapy education was not collected. Also, the nature of the survey did not allow the respondent to request clarifications on survey questions which allows for the possibility of some items being erroneously interpreted by the respondent. Additionally, information on the precise mechanism by which sports content was embedded into other curricular courses was not solicited nor was how the “sports” content was differentiated from musculoskeletal/orthopedic or strength and conditioning content.

1. Mulligan EP, Weber MD, Reinking MF. Competency revalidation study of specialty practice in sports physical therapy. Int J Sports Phys Ther. 2014; 9(7):959-73. 2. Zachazewski JE Felder CR Knortz K, et al. Competence revalidation study: A description of advanced clinical-practice in sports physical therapy. J Orthop Sports Phys Ther. 1994; 20(2):110-24. 3. Weber MD Thein-Nissenbaum J Bartlett L Woodall WR Reinking MF Wallmann HW Mulligan EP Competency revalidation study of specialty practice in sports physical therapy. N Am J Sports Phys Ther. 2009; 4(3):110-22. 4. Sports Physical Therapy Section of the American Physical Therapy Association. What is Sports Physical Therapy? 2012. Available at https://spts. org/about-spts Accessed March 29, 2017. 5. Mulligan EP. Texas Physical Therapy Association Annual Conference – Galveston, TX. Attributes and Attitudes of Board Certified Sports Clinical Specialists. Research Poster Presentation, 2014.

While the response rate of 31% is consistent with many studies evaluating specific components of educational curricula or validation of specialty areas of physical therapy practice it does not represent all programs and has a 10% margin of error. 1, 16-18 It is certainly possible that programs that do not have a curricular emphasis on concepts related to sports physical therapy chose not to respond to our survey request and the results are skewed towards programs with at least some interest in this area of physical therapy practice. Consequently, the results of this study should not be generalized to all CAPTEaccredited physical therapy education programs in the U.S. and only represent an initial description of curricular tendencies in regards to the instruction of sports physical therapy. CONCLUSION: This survey provides the first overview of the prevalence of sports physical therapy education in professional degree programs in the U.S. The findings should be used to spur further discussion on the

REFERENCES

6. Mulligan EP. Texas Physical Therapy Association Annual Conference – Galveston, TX. Attributes, Attitudes, and Specialization Examination Success of Residency-Trained Sports Physical Therapists. Research Poster Presentation, 2014. 7. Boissonnault W, Bryan JM, Fox KJ. Joint manipulation curricula in physical therapist professional degree programs. J Orthop Sports Phys Ther. 2004; 34(4):171-8. 8. Boissonnault W, Bryan JM. Thrust joint manipulation clinical education opportunities for professional degree physical therapy students. J Orthop Sports Phys Ther. 2005; 35(7):416-23. 9. Boissonnault WG, White DM, Carney S, Malin B, Smith W. Diagnostic and procedural imaging curricula in physical therapist professional degree programs. J Orthop Sports Phys Ther. 2014; 44(8):57986, B1-12.] 10. Noteboom JT, Little C, Boissonnault W. Thrust joint manipulation curricula in first-professional physical therapy education: 2012 update. J Orthop Sports Phys Ther. 2015; 45(6):471-6.

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11. Harrington K. Aggregate Residency/Fellowship Program and Applicant Data. 2015 Annual Residency/Fellowship Report to the American Board of Physical Therapy Residency and Fellowship Education. Alexandria, VA. 2016. 12. BOC Exam Candidate Handbook. 2017. Available at http://www.bocatc.org/images/stories/candidates/ boc%20candidate%20handbook_december2016%20 -%20final.pdf. Accessed April 4, 2017. 13. Imaging Education Manual for Doctor of Physical Therapy Professional Degree Programs. 2015. Available at https://www.orthopt.org/uploads/ content_files/files/IMAGING_EDUCATION_ MANUAL_FINAL_4.15.15.pdf. Accessed April 4, 2017. 14. Foot and Ankle Curricular Guidelines for Physical Therapist Professional Degree Programs. 2015. Available at http://www.apta.org/uploadedFiles/ APTAorg/Educators/Curriculum_Resources/ Section/FASIG_Curricular_Guidelines_June_24.pdf.

15. APTA Section Curriculum Resources for PT and PTA Educators. 2017. Available at http://www.apta.org/ educators/curriculum/section/. 16. Nelson PR, Boissonnault JS, Ankerson K, Figures C, Dockter MK. Survey on curricular content for doctor of physical therapy guidelines for women’s health content in professional physical therapist education: 2014 update. J Womens Health Phys Ther. 2016; 40(2):61-76. 17. Johanson MA, Miller MB, Coe JB, Campo M. Orthopaedic Physical Therapy: Update to the Description of Specialty Practice. J Orthop Sports Phys Ther. 2016; 46(1):9-18. 18. Pullen SD, Bruns EL, Dawkins NG, Powell HV, Miller CM, Sperle CR. HIV-related content in physical therapist education program: A curricular needs assessment. J Phys Ther Educ. 2017; 31(1):80-85.

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IJSPT

ORIGINAL RESEARCH

SHOULDER PAIN IN COMPETITIVE TEENAGE SWIMMERS AND IT’S PREVENTION: A RETROSPECTIVE EPIDEMIOLOGICAL CROSS SECTIONAL STUDY OF PREVALENCE Monica Tessaro1 Giorgio Granzotto2 Antonio Poser3 Giuseppe Plebani4 Alex Rossi5

ABSTRACT Background: The term “swimmer’s shoulder” was first introduced in 1974 by Kennedy and Hawkins to describe a common condition among competitive swimmers characterized by pain and dysfunction of the shoulder complex. Currently, the term does not define a specific clinical diagnosis and its etiology is considered to be multifactorial. In the literature shoulder pain prevalence varies according to the adopted definitions (from 3% to 91%); however, in the Italian environment there is no prevalence study regarding swimmer shoulder. Prevention by means of dry land activities may assist in delimiting shoulder pain in swimmers. Purposes: The purpose of this study was to investigate the prevalence of swimmer’s shoulder over the prior 12 months among teenage athletes and the preventive activities carried out across different sport’s teams. A second purpose was to determine whether the extent of the condition is affected by dry land preventive activity. And finally, to compare different preventive activities related to the prevalence of swimmer’s shoulder. Study design: Retrospective epidemiological cross-sectional study of prevalence Methods: Athletes from four levels of training: Esordienti A, Ragazzi, Juniores and Cadetti (according to Italian Swimming Federation F.I.N.’s partition age) belonging to eight Italian swimming teams and their respective coaches were involved in this study. Two types of questionnaires were created and completed by both the athletes and their coaches during May 2015. The collected data were analyzed by means of descriptive and inferential statistics. Results: Shoulder pain prevalence over the previous 12 months from the completion of the survey was 51%. In six out of eight of the societies a specific shoulder dry land warm-up was carried out before water training, whereas among seven out of eight societies also utilized weekly sessions of performance (physical) training. Statistically significant differences were noticed between shoulder pain and gender, weekly frequency and duration of dry land warm-up and duration of physical training. Conclusion: The results of the current study indicate that shoulder pain is prevalent in youth swimmers (51%) and appears to be affected by dry land preventive activities. A weekly frequency of dry land warm-up more than five times appeared to protect swimmers from pain (p=0.044); whereas, a dry land warm-up duration greater than 10 minutes seems to cause shoulder pain (p=0.043). A single physical training duration lower than 45 minutes seems to be associated with pain (p=0.035). Levels of evidence: 3a Key words: Dry land warm-up, prevention, shoulder pain, swimmer’s shoulder

1

Valdobbiadene, Treviso, Italy ULSS 2 Marca Tevigiana, Treviso, Italy 3 University of Padua, Padua, Italy 4 University of Siena, Siena, Italy 5 University of Rome “Tor Vergata”, Rome, Italy 2

CORRESPONDING AUTHOR Monica Tessaro Valdo Salute, Valdobbiadene, Treviso, Italy, +393496692858 E-mail: monicatessaro93@gmail.com

The International Journal of Sports Physical Therapy | Volume 12, Number 5 | October 2017 | Page 798 DOI: 10.16603/ijspt20170798

INTRODUCTION Swimmer’s shoulder The term “swimmer’s shoulder” does not define a specific clinical diagnosis, but rather indicates a typical condition among competitive swimmers characterized by pain and dysfunction of shoulder complex.1 This term was first used in 1974 by Kennedy and Hawkins to describe a common and painful syndrome of repeated shoulder impingement in swimmers.2 Furthermore, this definition specifies that the pain is referred to the anterior area of the shoulder during or at the end of training, compromising athletes’ performance during competitions.3 According to a study published in 1974,2 the prevalence of shoulder pain in swimmers was 3% whereas in more recent publications the percentage has increased up to 91%. The considerable gap between the two figures lies both in the difference between the underlying assumptions used to establish the definition of the painful event and also in the different inclusion and exclusion criteria adopted. At present, a clear consensus is lacking regarding the causes of shoulder pain in swimmers and the etiology of swimmer’s shoulder is considered to be multifactorial.3 Kennedy and Hawkins originally suggested that this syndrome was caused by repetitive primary shoulder impingement (outlet impingement) of the supraspinatus tendon and/or the long head of biceps tendon under the anterior inferior one third of the coracoacromial arch coupled with recurrent episodes of avascularity of these two tendons.3,4,5 However, there is no evidence suggesting that the incidence of primary impingement is greater in the swimming population than in the ordinary population.5 Two authors subsequently differentiated primary from secondary impingement (or “non-outlet impingement”).3,6 Secondary impingement can be defined as impingement secondary to the instability of the glenohumeral joint (GHJ). The term “instability” is referred to any structural or functional deficit in the GHJ leading to pathologic motion of this joint. Instability can be defined also as a symptomatic laxity.5 Factors contributing to the development of swimmer’s shoulder include: neuromuscular system alterations, joint overload, muscular soreness

and imbalances, excessive or reduction of flexibility, biomechanics of swimming, style technique and training mistakes.3,7,8 To date, GHJ laxity is no longer considered as one of the most important etiological factors.7 Prevention of swimmer’s shoulder Several authors have suggested that prevention programs based on dry land activities should be employed in order to reduce risk factors in predisposed subjects and to restrict the pathology’s onset in the other subjects.3,9,10,11 In a systematic review, the authors suggested that prevention may be especially important for collegiate freshman swimmers who in their early eligibility years are unaccustomed to the considerable collegiate level yardage that is required, and appear to be more prone to injury.11 This conclusion agrees with the study result of Bak et al who found that the main factor in the development of swimmer’s shoulder seems to be the high training volume during adolescence without an organized dry land training program which affects muscular balance of the shoulder complex.8 The proposed preventative activities include the training of strength, resistance, balance, muscular flexibility and stability, the improvement of proprioception and neuromuscular control, and the correction of swimming technique. It is important to point out that warm-up should not lead to muscular fatigue because performance may be compromised. Several authors have investigated the use of warm-up for preventing injuries but there is a lack of studies regarding warm-up effectiveness in swimming.12,13 A recent systematic review also pointed out the lack of research into prevention programs in non-contact sports (such as swimming) and their effect on upper extremity injuries.14 Recent authors have indicated that pre or post-exercise static muscle stretching in different sports neither reduces delayed-onset muscle soreness (DOMS) in young healthy adults,15 nor prevents injuries14 or improves performance.16 Stretching can be effective for people subject to serious muscular stiffness.15 Furthermore, there is strong evidence that high load dynamic warm-up enhances upper body and strength performance through sport specific movements in different sports.16 A recent systematic review and meta-analysis shows that strength

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training seems to reduce muscle skeletal injuries to less than one third, but no one of the included randomized controlled trials studied a swimmers population.14 Despite the lack of evidence related directly to swimming, multiple types of warm-up programs may be useful for swimmers. Painful shoulder biomechanics in swimmer In 1991 Pink et al conducted an electromyographic and cinematographic analysis of the normal freestyle stroke and studied the main differences in muscular activity between the painful shoulder and the non-painful shoulder.4,17 The observed changes of the phases of the stroke were at first considered as a direct effect of the attempt to avoid Neer’s sign.4 However, another study’s authors stateed that it is unknown whether the stroke alterations seen in painful swimmers are the cause or a consequence of the pain.17 Specifically, in swimmers with painful shoulders the main difference in muscle action was markedly lower serratus anterior activity during middle-pull through resulting in shoulder instability and in compensatory use of the rhomboids.4 Although this is not the only way to limit shoulder instability, these two muscles are designed to function antagonistically so when the rhomboids contract, the direction of pull is directly opposed to that of the serratus anterior, causing asynchronous muscle action and poor steering of the scapula which affects GHJ stability.4 Another asynchrony is related to the decrease in activity of the subscapularis during mid-recovery and an overall general increase of activity of the infraspinatus muscle.4 Similar to the serratus anterior, the subscapularis is susceptible to fatigue because of its continual activity in swimmers. Moreover, the subscapularis may decrease its function to avoid the painful degree of internal rotation required during the freestyle stroke. During hand entry in swimmers with painful shoulders, there is a decrease in activity of the anterior and middle deltoids and in the upper trapezius and rhomboids; at hand exit there is also a reduction in activity of the two heads of the deltoid. This reduced activity is related to the dropped elbow position seen during recovery which is one of the hallmark signs of injury. The dropped elbow allows the swimmer to decrease the degree of humeral internal rotation in order to avoid pain and lets the swimmers enter

the water with a wider hand entry.4 The swimmer with shoulder pain may present an asymmetric pull: the painful arm may not generate forces equal to the contralateral side causing difficulties in staying at the center of the lane and consequently leading to compensation by decreasing the pull on the contralateral side or by changing the beat of the kick. In order to recognize this painful condition, it is important to pay attention to other signs such as the early hand exit and the excessive body roll.4 In subsequent years, other studies by Pink and Ruwe analyzed the electromyography and cinematographic activity of the painful shoulder related to butterfly stroke and to breaststroke finding similar pathological signs.17 Despite a many studies regarding differences in muscular activity and stroke biomechanics between athletes with painful and non-painful shoulders, a cause and effect relationship between these two elements cannot be inferred.17 However, most believe that shoulder pain is mainly a biomechanical problem due to muscular dysfunction and imbalances. Therefore, the purpose of this study was to investigate the prevalence of swimmer’s shoulder over the prior 12 months among teenage athletes and the preventive activities carried out across different sport associations. A second purpose was to determine whether the extent of the condition is affected by dry land preventive activity. And finally, to compare different preventive activities related to the prevalence of swimmer’s shoulder. METHODS Study design This was a retrospective observational study. It was achieved through the creation and completion of questionnaires by competitive teenage swimmers belonging to different sports teams and categories, and their coaches. Setting Eight Italian competitive sports teams affiliated with the Italian Swimming Federation (F.I.N) participated in the study. There were 274 athletes affiliated with these teams. Before the survey distribution, authorizations from all sport’s teams’ presidents were obtained. Each participant agreed

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to personal data processing and signed the form in compliance with the Italian Legislative Decree no. 196 dated 30/06/2003. In May 2015 the paper questionnaires were delivered personally to one coach for each sports team who allocated them to their athletes. After three to four weeks as arranged with the coaches, the questionnaires were collected and withdrawn by the author. Participants The inclusion criteria for questionnaire assignment were: competitive swimmers belonging to any of the following four categories of Italian swimmers: Esordienti A, Ragazzi, Juniores and Cadetti. These categories are defined according to F.I.N.’s partition age: Esordienti A= Males (M) 12-13 years old, and females (F) 11-12 years old; Ragazzi= M 14-16 years old, and F 13-14 years old; Juniores= M 17-18 years old, and F 15-16 years old; and Cadetti= M 19-20 years old, and F 17-18years old. All subjects (athletes and trainers) agreed to allow personal data processing giving their informed consent. Athletes belonging to other categories were excluded; as were as athletes with previous history of injury that required a following operation to one or both shoulders before the survey. Variables The questionnaire for the athletes was organized into five sections: 1) the study introduction letter; 2) the form for informed consent in compliance with the Italian Legislative Decree no. 196 dated 30/06/2003; 3) personal and anthropometric data (name, date of birth, gender, weight, height), swimming data and training data (years of competitive swimming, specialty, weekly frequency and duration of training, weekly volume) and other sports data (current or past practice of other sports, level, years of practice, weekly frequency, duration training); 4) shoulder pain prevalence and characteristics of pain (number of events, work load, side, age at the first or unique event, period of the last event, training phase, numerical pain scale (NPRS) regarding pain intensity, stroke, objects, consequences, pain reliefs); 5) shoulder pain prevention strategies utilized (dry land warm-up and general physical training and information regarding prevention exercises usefulness).

The questionnaire for the coaches was organized in three sections: 1) the study introduction letter; 2) personal data (name, society name, years as coach), training data (trained categories, range of age trained, weekly frequency, duration and volume of the training and weekly volume); 3) six questions regarding: warm-up activity (mobilizations/ overhead activities/stretching/muscular strengthening) and their characteristics (frequency, duration) and the reasons if they were not performed; physical training (period of practice, weekly frequency, duration, presence of a physical trainer); the most common stroke used during training; the need for changing programs because of shoulder pain experienced by swimmers; eventual drop out from competitions due to shoulder pain; the overall knowledge about “swimmer’s shoulder”. Bias The questionnaires were pilot tested with two athletes and two coaches in advance to assess their understandability. After analyzing the contributions of the pilot subjects, three questions were adjusted. All athletes filled out the questionnaires in the same month during the survey to avoid possible differences regarding the training session and competitions. This study could present a selection bias: the questionnaire was assigned to all athletes of the eight sport’s teams but there were different rates of compliance among the eight teams. Moreover, some sport societies may have chosen only the strongest athletes to be part of the team. For these reasons, the results of this study sample may not be representative of all swimmers. Extent of the study Statistical methods Data was managed and processed in an Excel spreadsheet. The Analysis Tool Pak that the application provides was used to conduct both descriptive and inferential statistics. The sample used for the main analysis of causality between pain and different training variables consists of a total of 166 observations. The sample has been divided in two subgroups where the discriminant is the presence of pain versus no pain. The sub-group size is of 87 and

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Table 1. Athletes’ rate of compliance specific for each sport society (sports team) and athletes’ number divided into Italian Swimming Federation (FIN) categories.

79 observations respectively. The Student’s T-Test was used to investigate differences between groups. The T-Test was performed under the hypothesis of unpaired samples with different variances. The alpha value was set at p<0.05, as is commonly accepted in scientific publications. RESULTS 274 athletes were recruited for the participation and received the questionnaire; 204 completed it. Seven of those were excluded from the analysis because one of them was filled out illegibly and the remaining six had been completed by athletes belonging to not-included categories. Thus 197 questionnaires were included in the survey and used for statistical analysis. The rate of athletes’ compliance was 71.9% (197/274) (Table and Figure 1). All 19 coaches that were solicited participated in the study, for a response rate of 100% (19/19). Athletes sample description The sample consisted of 54.82% females and 45.18% males. The average age and its standard deviation (±) was 14.01 (±2.12) years. The average BMI was 18.96 (±2.42). According to F.I.N. categories the sample was composed of 36.04% Esordienti A, 39.09% Ragazzi, 17.26% Juniores and 7.61% Cadetti. Regarding the complete sample, the average number of

Figure 1. Athletes general rate of survey completion.

weekly training sessions was 5.27 (±0.81), with 2.12 (±0.28) hours for each training session, and 25.31 (±9.02) kilometers per week (Tables 2 & 3). Coaches sample description The average years of participation in coaching for the coaches was 10.5 (±6). They were distributed between societies: two coaches for Society 1, three coaches for Societies 2-3, one coach for Society 4, two coaches for Societies 5-6-7 and fours coaches for Society 8. Prevalence of shoulder pain The total sample prevalence of shoulder pain related to the 12 months prior to the questionnaires’ compilation was 51% (101/197): 51% belonging to Esordienti A, 47% to Ragazzi, 67% Juniores and

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Table 2. Training frequency and volume related to categories, reported by athletes.

Table 3. Training frequency and volume related to categories reported by coaches.

40% Cadetti’ categories. Moreover, the total sample with pain was composed 56% (61/108) of women and 45% (40/89) of men. With reference to “pain” sample, 71.29% (72/101) showed the symptoms within six months of the questionnaires’ completion, 28.71% (29/101) between six months and 12 months of the questionnaires’ completion. Sixteen point six percent (16/96) did not experience shoulder pain in the prior 12 months to completion of the survey and 83.33% (80/96) did not ever experience it during their sport career (Table 4). Table 5 reports shoulder pain prevalence related to athletes among sport’s teams.

Shoulder pain in relation to anthropometric and sport variables There was a statistically significant relation between shoulder pain and gender, with females more likely to experience pain (p= 0.048). No statistically significant differences were found between shoulder pain and weight (p= 0.386), height (p= 0.273), BMI (p= 0.495) and age (p= 0.317). With reference to sport variables, no statistically significant differences were found between pain and years of competitive swimming (p= 0.479), weekly training frequency (p= 0.114), training duration (p= 0.161) and weekly volume (p= 0.309).

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Table 4. Distribution of pain episodes by categories and interval.

Table 5. Pain prevalence among societies.

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Figure 4. Onset of most recent pain episode. Figure 2. Pain and distance specialty.

Figure 3. Pain and stroke specialty.

There were no statistically significant differences between pain and the current or past practice of another sport which demands overhead activities (such as volleyball, handball and tennis) in addition to swimming; however, such values approached statistical significance (current overhead sport practice p= 0.091; past overhead sport practice p= 0.106). Pain was more frequent in the sprinter swimmers (50 m and 100 m) with a respective prevalence of 12% and 41% (Figure 2). In reference to the swimming specialty the following prevalence of shoulder pain was experienced by the sample of the study: 54.7% freestyle, 56.5% butterfly, 40.3% backstroke, 44.9% breaststroke and 70% medley (Figure 3). Characteristics of pain The average number of pain episodes was two to three for the 51% of the subjects in pain sample. In pain

sample, 31% has been forced to reduce the swimming volume, that is stopping training and/or skipping the following trainings, whereas 69% did not reduce the swimming volume. Pain came out after 4.88 (±2.80) years of competitive swimming practice. The unique or the first pain event happened in a specific period of age: 15% at 11 years old, 22% at 12 years old and 16% at 13 years old. The most recent event occurred within one week of the questionnaire’s compilation for 22%, within previous month for the 44%, within the prior six months for 20%, and within the prior six and 12 months for 14% (Figure 4). The average duration of the pain episode was 4.5 days (±10). With regard to the timing of appearance of pain, 10% reported it during warm-up, 27% experienced it during the first half of training and the 47% experienced it during the second half of training, and the residual 16% said it began when out of the water after training. Shoulder pain intensity during training was evaluated by means of NPRS was 4.58 (±1.71), specifically 4.66 (±1.72) reported by women and 4.43 (±1.69) by men. Regarding stroke type, the pain was produced during freestyle for 52.44%, butterfly stroke for 27.19%, backstroke for 13.04% and 7.33% for breaststroke. Considering the specific phase of freestyle stroke, pain appeared during early-pullthrough phase (30.1%), late-pull through phase (27.4%), recovery phase (24%) and glide phase (18.5%) (Figure 5). All coaches stated freestyle as the most frequently performed stroke during training, even if they attempted to train the athletes using all the four strokes. After pain’s appearance, 45.33% of the swimmers reported that they would “continue the training even if I would need to stop, but with reduced intensity and effort”, 34% stated “I

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Figure 7. Reliefs for pain. Figure 5. Pain in relation to freestyle stroke phases.

Figure 6. Pain effects on training.

can continue the training with no changes”, 16.33% chose “I temporally stop and then I restart” and 4.33% signaled “I have to finish the training as I cannot carry on” (Figure 6). Figure 7 shows the reliefs taken by swimmers to resolve the pain. Moreover,

some athletes reported that their pain was produced or aggravated by the use of hand paddles (13 athletes), elastic bands (14), kick boards (10), and isotonic machines (2). Swimmer’s shoulder prevention Dry land shoulder-specific warm-up carried out before training in the pool was practiced by six out of eight societies included in the study, in particular 155 out of 197 athletes and 14 out of 19 coaches. Dry land shoulder-specific warm-up was carried out an average weekly frequency of 5.79 (±2.05) times with average duration 20.36 (±13.02) minutes (Table 6). The lack of dry land warm-up was justified by the coaches of the relevant societies due to insufficient time and the skills of the athletes being inadequate to for correct and efficient performance of the

Table 6. Frequency and duration of dry land warm-up for societies (sports teams).

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Table 7. Frequency, duration, and timing of physical training for societies.

exercises. Physical performance enhancement training was carried out by all societies except one at the beginning of the sport season or during the year with an average weekly frequency of 2.08 (±0.70) times and an average duration of 1.48 (±0.77) hours. In four out of seven societies coaches were supported by an athletic trainer (Table 7). Dry land program activities were based on the interactions with other coaches/sports trainers/physical therapists 54.8% of the time, on personal research (such as academic studies) 26.2% of the time, and on research material supplied by S.I.T. in 19%. Figure 8 shows the involved body regions included in dry land warm-up, the core and the lower limbs were the less trained areas during physical training. Figure 9 shows the different warm-up activities;

Figure 8. Body regions involved in dry land warm up.

Figure 9. Activities included in dry-land warm up.

strength training and active mobilization of the shoulders were performed more than stretching and overhead exercises. Finally, 12 out of 19 coaches stated that they were rarely forced to change training programs because of shoulder pain complained of by swimmers, only one coach declared he often changes his training programs and the remaining six coaches never needed to change their training programs because of athlete’s shoulder pain. Shoulder pain in relation to dry land warm-up and physical training variables Several variables of physical training showed statistically significant differences between the pain sample and the no pain sample. The weekly frequency of warm-up of the pain sample and the no pain one is on average respectively 4.70 and 5.13

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(p= 0.044), indicating that swimmers with a weekly frequency of more than five has less pain. Dry land warm-up minutes differed between the two groups (p= 0.043), indicating that a dry land warm-up duration of greater than 10 minutes was associated with greater shoulder pain. Finally training duration of a session was statistically different between groups, (p= 0.035), a training duration more than 45 minutes appearing to benefit the athletes. There were no other statistically significant differences in training variables between groups. DISCUSSION Shoulder pain in relation to anthropometric and sport variables The present study observed that the prevalence of swimmer’s shoulder was moderate among competitive teenage swimmers, with 51% of the participating athletes reporting at least one painful event during the 12 months preceding the collection of data. This value is greater than the results of the other international studies published in literature where prevalence ranges between 18% to 38%.1,9,18,19 Only Sein et al in their study found a higher prevalence value than the current study, equal to 91%.7 The variability of the results can be attributed to the different inclusion and exclusion criteria utilized in the studies; however, another plausible explanation may be athletes’ inability (in particular athletes belonging to the younger age categories such as Esordienti A) to differentiate between pain and soreness. It could be important that coaches define and teach this difference and their respective signs and symptoms to athletes in order to make swimmers aware of this condition, and to minimize the potential for cumulative damage as well as hasten the return to sport after an injury as Pink and Tibone stated in their study.4 The correlation between shoulder pain and sex was found to be statistically significant for females (p= 0.048). This result could be attributed to arm strokes being shorter than those of their male colleagues, which enhances the risk of suffering from an overuse injury due to the higher amount of arm revolutions per lap.3 Although this difference is small for short distances, it becomes significant for long distances, potentially causing major shoulder overload

for female swimmers. Another reason for this statistically significant correlation and for NPRS values regarding shoulder pain intensity which was higher among female swimmers (4.66 [±1.72]) than among male swimmers (4.43 [±1.69]) could be the different pain perception between sexes20. The literature shows that women have a lower pain thresholds in comparison with men and this seems to be affected by multiple biological (sex hormones) and psychosocial processes.21 Although there are described differences in laxity between males and females, it is likely not the major contributor to the multifactorial etiology of swimmer’s shoulder.1,7,9 Because the difference approached statistical significance (p= 0.091), it could be suggested that practicing another sport in addition to swimming that overloads upper limbs, may promote the onset of pain. To benefit from the effects of cross-training and to prevent the onset of shoulder pain, it may important to practice a sport or another physical activity which trains strength and core stability or develops aerobic capacity rather than impact sports and sports that use the upper extremities primarily, as Auvinen et al have suggested.22 In accordance with other publications,9,11,18 the results of this study did not demonstrate a statistically significant correlation between shoulder pain and weekly volume of training (p= 0.309); which contrasts with the popular opinion that swimmer’s shoulder is a consequence of volume of load on the shoulder’s complex. Characteristics of pain Seventy percent of the total sample experienced shoulder pain one to three times during the 12 months before data collection. The average duration of pain episodes was 4.5 days (±10) and pain relief strategies used to address the painful episode (49.5% do nothing and 6.4% rest and interrupt training) seem to indicate the self-resolving character of pain, which is likely due to soft tissue inflammation. The results of this study concur with the findings of Sein et al.7 and Tate et al.19 that specific swimming strokes have little effect in predisposing elite swimmers to shoulder pain and that early pull-through phase and late pull-through phase of freestyle stroke

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are the part of the stroke with a high frequency of pain onset (30% during early pull-through phase and 27% during late pull-through phase). It has been suggested that if during glide phase the rhomboids, anterior serratus and upper trapezius muscles are strained or are not recruited with the correct activation timing, they cannot allow a good GHJ stabilization predisposing swimmers to shoulder impingement.19 Shoulder pain in relation to dry land preventive activities The lowest percentage of injury was seen in Society (sports team) 2 equal to 36.67% (compared to the average injury percentage=55.96%); this value approached to critical value equal to 30.12%. Paradoxically Society 2 is one of the two societies that did not perform dry land warm-up, although physical training was utilized during the entire competitive season with the participation of a sports trainer. Conversely, Society 5 did not perform dry land warm-up but included physical training in September without participation of a sport trainer; in this case injury percentage was equal to 57.14% (greater than the general average). However, this result could be due to athletes’ rate of compliance to respond to the questionnaire which was the lowest one for Society 2 among the eight involved societies. Conversely, Society 4 showed an injury percentage among the highest, (equal to 75%) and this is the only society that did not utilize physical training. Therefore, from this qualitative comparison of data and considering sample differences it can be deduced that physical training represents an element which may significantly affect the onset and prevalence of pain. A separate comment is required for Society 6, which trains only athletes belonging to the Esordienti A category (youngest swimmers), who then move to Society 3 as they reach the adequate age. By comparing injury percentage, it can be noticed that Society 6 presents the highest value equal to 77.78% (rate of questionnaire compliance=100%) and Society 3 a value equal to 42.22% (rate of questionnaire compliance=81.82%). The considerable difference may be explained as the younger athletes’ difficulty distinguishing pain from soreness, as previously suggested, but also as the consequence of a natural selection according to which only athletes with good

physical condition or a low enough pain are the ones to continue competitive swimming. From the statistically significant correlations found in this study it appears that considering the quantity of warm-up in terms of both frequency and duration and the quality of warm-up are of fundamental importance. With regard to the statistically significant findings related to physical training, it can be observed that training, apart from swimming may play an important preventative role. Warm-up during physical training should include a general warmup including activities of moderate intensity which require use of large muscles and that enhance body temperature (such as cyclette or a light run) and a dynamic warm-up specific to activating muscles used in swimming through use of dynamic motions and elastic band exercises (for example: arm revolutions, dry land swimming movements, trunk rotations, internal/external GHJ rotation).23 From the results of recent studies in different sports (except swimming), static stretching should be performed only in the specific case of stiffness and muscular or capsular shortening as it does not show any protective injury effect, while strength training can improve performance and reduce muscle skeletal injuries.14 Results of the current study indicate that the core and lower limbs are the less trained areas during physical training; however, it is important to work intensely on core stability since a recent study noticed statistically significant correlations between shoulder pain and a low core performance assessed using the side bridge test, the prone bridge test and the closed kinetic chain upper extremity stability test.19 Other authors have stated that endurance training of core muscles is an essential component in any injury prevention program.3 Adequate corestability allows for efficiency during swimming, it facilitates powerful and efficient strokes and kicks without excess energy dispersion, contributes to the production of body rotation in freestyle and backstroke, and manages or controls body undulations in breaststroke and buttefly24. Training of the lower limbs serves a fundamental preventive role as it helps develop an adequate balance with the other elements of the kinetic chain reducing the risk of shoulder overload. This supports the findings of Bak

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et al. who stated that it was necessary to associate training in water with dry land training in order to influence muscular balance in particular during adolescence when the athlete’s bodies are continuously changing.8 Limitations The main limitation of this study is the questionnaire that was utilized. The authors developed this questionnaire for this research only and did not establish any reliability or validity statistics for it. Some pilot testing was utilized for clarifications, but no further analysis was performed. The structure of the questionnaire did not allow for deeper analysis by inferential statistics related to dry land preventive activities. Secondly, the lack of studies published in the literature regarding the prevention of injuries in swimming or upper limb injury prevention did not allow comparison of the results of this study with other evidence. Finally, as the study specifically excluded former-athletes who left their swimming career due to shoulder pain, it was not possible to examine how or whether this condition led to ceasing competition or training. CONCLUSION The results of this study demonstrate that swimmer’s shoulder is a prevalent condition among competitive adolescent swimmers and that it is related to by warm-up and dry land physical training practices. Although this study included about 200 competitive teenage swimmers, further investigations are needed to analyze the preventive role of dry land programs on swimmer’s shoulder. REFERENCES 1. Mc Master WC, Roberts A, Stoddard T. A correlation between shoulder laxity and interfering pain in competitive swimmers, Am J Sports Med. 1998; 26(1):83-86. 2. Kennedy JC, Hawkins RJ. Swimmer’s shoulder. Phys Sports Med. Vol. 2. McGraw-Hill, New York, 1974:3538. 3. Wanivenhaus F, Fox A, Chaudhury S, et al. Epidemiology of injuries and prevention strategies in competitive swimmers. Orthop Surg. 2012; 4(2):246-251. 4. Pink M, Tibone J. The painful shoulder in the swimming athlete. Orthop Clin North Am. 2000; 31:247-261.

5. Blanch P. Conservative management of shoulder pain in swimming. Phys Ther Sport. 2004; 5:109-124. 6. Belling, Sørensen AK, Jørgensen U. Secondary impingement in the shoulder. Scand J Med Sci Sports. 2000; 10:266–278 7. Sein M, Walton J, Linklater J, et al. Shoulder pain in elite swimmers: primarily due to swim-volumeinduced supraspinatus tendinopathy. Br J Sports Med. 2010; 44(2):205-213. 8. Bak K. The practical management of swimmer’s painful shoulder: etiology, diagnosis and treatment. Clin J Sport Med. 2010; 20(5):386-90. 9. Walker H, Gabbe B, Wajswelner H, et al. Shoulder pain in swimmers: a 12 months prospective cohort study of incidence and risk factors. Phys Ther Sports. 2012; 13:243-249. 10. Borsa PA, Scibek JS, Jacobson JA, et al. Sonographic stress measurement of glenohumeral oint laxity in collegiate swimmers and age matched controls. Am J Sports Med. 2005; 33:1077-1084. 11. Wolf B, Ebinger A, Lawler M, et al. Injury patterns in Division I collegiate swimming. Am J Sports Med. 2009; 37(10):2037-41. 12. Neiva HP, Marques MC, Barbosa TM, et al. Warm-up and performance in competitive swimming, Sports Med. 2014; 44:319-330. 13. Balilionis G, Nepocatych S, Ellis CM, et al. Effects of different types of warm-up on swimming performance, reaction time and dive distance. J Strength Cond Res. 2012; 26(12): 3297–3303. 14. Lauersen JB., Bertelsen DM, Andersen LB. The effectiveness of exercise interventions to prevent sports injuries: a systematic review and metaanalysis of randomised controlled trials. Br J Sports Med. 2014; 48:871-877. 15. Herbert RD, de Noronha M, Kamper SJ. Stretching to prevent or reduce muscle soreness after exercise. Cochrane Database of Systematic Reviews. Issue 7. Art. No.: CD004577. DOI: 10.1002/14651858.CD004577. pub3; 2011. 16. McCrary JM, Ackermann BJ, Halaki M. A systematic review of the effects of upper body warm-up on performance and injury. Br J Sports Med. 2015; 49:935–942. 17. Heinlein S, Cosgarea A. Biomechanical considerations in the competitive swimmer’s shoulder. Sports Phys Ther. 2010; 6:519-525. 18. Bailón-Cerezo, J. Torres-Lacomba, M. y GutiérrezOrtega, C. Prevalencia del dolor de hombro en nadadores de competición: estudio piloto / Shoulder Pain Prevalence in Competitive Swimmers: A Pilot Study. Rev Int Med Cienc Act Fís Deporte. 2016; 16:317-334.

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19. Tate A, Turner G, Knab S, et al. Risk factors associated with shoulder pain and disability across the lifespan of competitive swimmers. J Athl Train. 2012; 47(2):149-158. 20. Rollmann GB, Lautenbacher S. Sex differences in muscoloskeletal pain. Clin J Pain. 2001; 17:20-24. 21. Bartley EJ, Fillingim RB. Sex differences in pain : a brief review of clinical and experimental findings. Br. J. Anaesth. 2013;111(1):52-58. 22. Auvinen JP, Tammelin TH, Taimela SP, et al. Muscoloskeletal pains in relation to different sport

and exercise activities in youth. Med Sci Sports Exerc. 2008; 40(11):1890-1900. 23. Salo D, Riewald S. “Riscaldamento e raffreddamento” In La preparazione atletica per il nuoto. Libreria dello Sport; 2013:19-32. 24. Salo D, Riewald S. “Esercizi per la stabilità del tronco” In La preparazione atletica per il nuoto. Libreria dello Sport; 2013:87-110.

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IJSPT

ORIGINAL RESEARCH

AGE DIFFERENCES IN MEASURES OF FUNCTIONAL MOVEMENT AND PERFORMANCE IN HIGHLY TRAINED YOUTH BASKETBALL PLAYERS Oliver Gonzalo-Skok, PhD1 Jorge Serna, PhD1 Matthew R. Rhea, PhD2 Pedro J. Marín, PhD, PT3

ABSTRACT Background: There is a lack of information about the influence of age on functional movement tests (FMT) and performance tests as well as in their relationships in young basketball players. Purpose: The purpose of the present study was to determine the variations in FMT and jump and/or sprint performance scores between age groups (U-14 vs. U-16) in Highly-trained young basketball players. The second purpose was to investigate the relationship between FMT for lower body and jump and/or sprint performance in highlytrained young (U-14 and U-16) male basketball players. Study Design: Descriptive study. Methods: Thirty elite young (U-14 to U-16) male basketball players performed several FMT (weight-bearing dorsiflexion test [WB-DF] and a modified Star Excursion Balance test [SEBT]) and performance including unilateral and bilateral countermovement jumps, unilateral horizontal jumping, linear sprinting and performance tests. Results: All anthropometric and performance tests showed a statistically significant advantage (p<0.05) in the U-16 group, excluding the unilateral jump with left leg (p=0.127). Five out of the eight FMT performed showed a statistically significant advantage (p<0.05) in the U-16 group. The U-14 group did not differ statistically from the U-16 group in WB-DF with left leg and the SEBT anterior right leg and posteromedial left leg reaches. Effect size calculations did show small to moderate effects in favor of U-16. Only two significant correlations (p<0.05) between functional movement and performance measures were identified in the U-16 group for either limb (10-m sprint and SEBT-PLL, SEBTCompositeL), while a total of 13 significant correlations (p<0.05) in the U-14 group were found. Conclusions: The results of this study demonstrated differences in FMT and jump and/or sprint performance test between age groups (U-16 vs U-14). The findings of this study support the idea that the age of the player should be considered when interpreting FMT scores, which could have implications when implementing the FMT for injury risk prediction. Level of evidence: 2b Key Words: Functional testing, sports performance, sprinting speed, vertical jump

1

Faculty of Health Sciences, University of San Jorge (USJ), Zaragoza, Spain. 2 A.T. Still University, Mesa, AZ, USA 3 CYMO Research Institute, Valladolid, Spain. Conflict of interest The last author declared potential conflicts of interest. He has patented the LegMotion system and OctoBalance system.

CORRESPONDING AUTHOR Pedro J. Marín, PhD. CYMO Research Institute, Valladolid, Spain. E-mail: pjmarin@cymori.com

The International Journal of Sports Physical Therapy | Volume 12, Number 5 | October 2017 | Page 812 DOI: 10.16603/ijspt20170812

INTRODUCTION The ability to perform high intensity actions (HIA) is an important prerequisite for successful participation in most team-sports.1,2 Several authors have shown that HIA such as acceleration,3 maximum running speed,4 change of direction ability (CODA)4 and explosive power5 are related to match performance and competitive level. Specifically, 83% of goals in soccer are preceded by at least one powerful action made by the scoring or the assisting player.6 Furthermore, international basketball players perform significantly more HIA than their national counterparts.7 Thus, power and speed abilities seem to be relevant in decisive situations in team-sports. Functional movement tests (FMT) examine the ability of the body to move through sufficient range of motion (ROM) to perform dynamic tasks and include the weight-bearing dorsiflexion test (WB-DF) and the Star Excursion Balance test (SEBT). It is worth noting that a limited WB-DF score and a substantial between-limbs difference in the anterior direction in the SEBT seem to indicate a greater injury risk in several pathologies.8-10 For example, limited ankle dorsiflexion has been shown as a risk factor for developing patellar tendinopathy in junior elite basketball.8 Furthermore, those team-sports players who have suffered an anterior cruciate ligament reconstruction reach lower anterior distances with both limbs (involved and uninvolved) during the SEBT.9 In addition to this information, the functional asymmetries presented in functional movement or jumping tests are also a predictive measure of lower extremity injuries. In this regard, an individual with a difference greater than 4 cm in the anterior SEBT reach distance is 2.5 times more likely to sustain a lower extremity injury.10 Additionally, a difference greater than 1.5 cm in the WB-DF can be considered as a cut-off to predict a lower extremity injury.11 Also, an asymmetry equal to or above 10% during jumping tasks detects players at higher injury risk (i.e., four fold).12 Thus, it seems that the use of these measures in a physical fitness testing battery might be important in determining risk of injury. Recently, the relationship between functional asymmetries and performance tests has received some research attention. For example, players displaying greater symmetry during functional testing

(assessed via unilateral vertical jump or distance reached during a dynamic balance test) are faster than their asymmetrical counterparts during linear and change of direction (COD) sprint tests.13 Asymmetries in the WB-DF are also related to decreased performance in COD tasks.14 As such, it seems that functional asymmetries might play a key role in performance. However, there is scarce information about the age-related differences in FMT and performance in young basketball players. Thus, the purpose of this study was to determine the variations in FMT and jump and/or sprint performance scores between age groups (U-14 vs. U-16) in highly-trained young basketball players. The second purpose was to investigate the relationship between FMT for lower body and jump and/or sprint performance in highly-trained young (U-14 and U-16) male basketball players. It was hypothesized that: i) U-14 players would have decreased FMT and jump and/ or sprint performance scores compared with U-16 and, ii) based on the aforementioned studies, was that the younger age group would have higher correlations between the FMT and performance tests. METHODS Experimental approach to the problem A crossover study design, in which the participants were randomly assigned, was utilized for this study. The season lasted 10 months. The first two months were the pre-season period (August and September). Thereafter, the competitive period comprised eight months (from October to May). The study was conducted during April and May. Several FMT (weightbearing dorsiflexion test and modified star excursion balance test) and performance tests (jumping, sprinting and changing direction tests) were administered. All players were familiar with the procedures of all tests (they had performed all tests at least six times) and were asked not to perform any strenuous exercise during the day before testing. Players were also asked to follow their normal nutritional habits on the day of the test. FMT were executed the same day and in the same order (WB-DF and modified SEBT) while performance tests were performed another day and also in the same order (jumping, sprinting and COD tests). The first day all players performed all FMT, while the second day they executed all

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performance tests. All tests were conducted at the same time of the day (18:00 to 20:00) on two different days separated by 72 h. Subjects Thirty elite young male basketball players (U-16, n=15; 15.6 ± 0.6 years; U-14, n=15; 13.7 ± 0.5 years) volunteered to participate in the present study. Players belonged to a first Spanish basketball division (ACB-Liga Endesa) club academy squad. All players participated in an average of 12 hours of combined basketball (6-7 sessions), strength/power (two sessions) and speed, agility and quickness (SAQ) (one session) training sessions plus two competitive matches per week. At the time of the study, all players were competing at the national level (i.e., Spanish National Basketball League). Furthermore, some players (n=6) were also competing at the international level (i.e., European and World Basketball Championships). Written informed consent was obtained from both the players and their parents before beginning the investigation. The present study was approved by the institutional research ethics committee, and conformed to the recommendations of the Declaration of Helsinki. Functional movement tests Weight-bearing dorsiflexion test Ankle dorsiflexion was evaluated through the LegMotion system (LegMotion, your MOtion®, Albacete, Spain).15 Each player started with their hands on their hips, and put the assigned foot on the middle

of the longitudinal line just behind the transversal line on the platform (Figure 1). The alternate foot was positioned off the platform with toes at the edge of the platform. Each trial consisted of flexing the ankle as much as possible without raising the heel of the assessed ankle trying to touch a marker, situated just behind the patella, with their knee. The distance achieved was recorded in centimeters. Three trials were allowed with each ankle (i.e., left and right) with 10 seconds of passive recovery between trials. The third value in each ankle was used in subsequent analysis of weight-bearing dorsiflexion (WB-DF). Modified Star Excursion Balance Test Dynamic balance was assessed by using the OctoBalance device (OctoBalance, Check your MOtion®, Albacete, Spain), a modified version of the SEBT (Figure 2), which analyzed three lower limb excursion directions: anterior (SEBT-A), posteromedial (SEBTPM) and posterolateral (SEBT-PL).14 The measurement system is based on an extending measuring tape, which is magnetized to an octagonal platform in each direction, to measure the distance reached. Each trial consisted of pushing the marked point, situated at the top of the measuring tape, with the toes (i.e, big toe) as far as possible in the designated direction. Prior to the commencement of each trial, the measuring tape was established at 30 cm. Each trial was validated by a visual inspection to ensure that each trial was performed without putting the toes on the marked point, and to ensure that their

Figure 1. The International Journal of Sports Physical Therapy | Volume 12, Number 5 | October 2017 | Page 814

Figure 2.

heel remained on the anterior-posterior line on the platform (the whole foot must be on the platform and with the heel on the border line of the octagon). Players were instructed to maintain their hands on their hips throughout the test. Warm-up consisted of two trials with each leg (i.e., two with left stance and two with right stance). Thereafter, three trials were allowed with each leg with 10 seconds of passive recovery between trials. The mean result of the three trials for each leg was used for subsequent analysis.14 Performance tests Bilateral countermovement jump (CMJ) test Lower limb bilateral explosive power was assessed using a vertical countermovement jump (CMJ) (centimeters) with flight time measured by the Optojump (Optojump, Microgate, Bolzano, Italy) to calculate jump height.16,17 Each trial was validated by a visual inspection to ensure that each jump was without any leg flexion, each landing was without any leg flexion on the first contact time and, thereafter, the subject was allowed to flex the hip, knee and ankle for better absorption of forces. Subjects were instructed to maintain their hands on their hips during CMJ. The depth of the CMJ was self-selected. Each test was performed three times, separated by 45 seconds of passive recovery, and the best jump was recorded and used for analysis.

Unilateral countermovement jump (CMJ) test Each subject started by standing solely on the designated leg, maintaining their hands on their hips during unilateral CMJ and the alternate leg flexed to 90° at the hip and knee. Players were asked to jump as high as possible and to land on the assessed leg (Optojump, Microgate, Bolzano, Italy). Leg swing of the alternate leg was not allowed. Failure to maintain proper technique resulted in an invalid jump (i.e., loss of hands on hips, 90° flexion, or use of leg swing). Each test was performed twice, separated by 45 seconds of passive recovery, and the best jump for each leg was recorded. The variables used for analyses were: 1-legged left CMJ (CMJL) and 1-legged right CMJ (CMJR). Unilateral horizontal jump (HJ) test Unilateral horizontal jump test was measured using a regular measuring tape. Each subject stood with the toes of the designated leg positioned just behind a starting line (marked with tape), hands placed behind the back and the alternate leg flexed to 90° at the hip and knee. When ready, each subject flexed then rapidly extended the assessed leg and jumped as far as possible (forward distance). The subjects were instructed to perform a controlled, balanced landing and to stick the landing for 2-3 s until the tester registered the landing position. No extra hops were allowed during testing. Failure to hold the

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landing position for 2-3 s resulted in a disqualified hop. The point of the shoe closest to the starting line upon landing was used to determine the distance jumped. Leg swing of the alternate leg was allowed. Each test (left and right) was performed twice, separated by at least 45 seconds of passive recovery, and the best jump for each leg was recorded. The variables used in analyses were: 1-legged left HJ (HJL) and 1-legged right HJ (HJR).

differences was also expressed as standardized mean difference (Cohen effect sizes, ES). The criteria to interpret the magnitude of the ES were as follows: <0.2 trivial, >0.2 to 0.6 small, >0.6 to 1.2 moderate, >1.2 large.19 Relationships between variables were determined using Pearson´s correlations. The significance level was set at p ≤ 0.05. Data were analyzed using PASW/SPSS Statistics 20.0 (SPSS Inc, Chicago, IL, USA).

Speed tests Running speed was evaluated by 25-m sprint times (standing start) with 5-m, 10-m and 20-m split times. The front foot was placed 0.5 m before the first timing gate. Time was recorded with photoelectric cells (Witty, Microgate, Bolzano, Italy). The 25-m sprint was performed twice, separated by at least three minutes of passive recovery. The best time was recorded for analysis.

RESULTS Descriptive values for anthropometric data are reported in Table 1. All data were found to be normally distributed. As would be expected based on maturation, U-16 players were taller, heavier, and had a larger wingspan compared to U-14 players.

180° Change of direction test A 10-m sprint test was performed. The front foot was placed 0.5 m before the first timing gate (Witty, Microgate, Bolzano, Italy). Each player sprinted from the start/finish line, completely crossed the 5-m line with either right or left foot, and turned 180° to sprint back to the start/finish line. Players executed two valid trials with each foot, separated by at least two minutes, with the fastest retained for calculations. The variables used in analyses were COD 180° with left (COD180L) and right leg (COD180R). V-cut test In the V-cut test, players performed a 25-m sprint with 4 CODs of 45° each 5 m.18 The front foot was placed 0.5 m before the first timing gate (Witty, Microgate, Bolzano, Italy). For the trial to be valid, players had to pass the line, placed on the floor, with one foot completely at every turn. If the trial was considered a failed attempt, a new trial was allowed. The distance between each pair of cones was 0.7 m. Players performed two trials separated by at least three minutes. Time of the fastest trial was recorded.

Performance tests Performance tests are reported in Table 2. All performance tests showed a significant advantage (p<0.05) in the U-16 group excluding the CMJL (p=0.127). Functional movement tests Descriptive values for FMT are provided in Table 3 and Figure 3. Five out of the eight FMT performed showed a statistical advantage (p<0.05) in the U-16 group. While the U-14 group did not differ statistically from the U-16 group in WB-DFL, SEBT-AR, and SEBT-PML, ES calculations did show small to moderate effects in favor of U-16. Correlations The correlations between the FMT and performance tests are reported in Table 4 and Table 5. Only two moderate significant correlations (r= 0.547 to 0.561; p<0.05) between functional movement and performance measures were identified in the U-16 group for either limb (0-10m and SEBT-PLL, SEBT-CompositeL). Table 1. Anthropometric data and between-group comparisons for U-14 and U-16 basketball players. Bolded values represent statistically significant differences.

Data analysis Data are presented as mean ± SD. The distribution of each variable was examined with the Shapiro-Wilk normality test. The magnitude of between-session The International Journal of Sports Physical Therapy | Volume 12, Number 5 | October 2017 | Page 816

Table 2. Performance test data and between-group comparisons for U-14 and U-16 basketball players. Bolded values represent statistically signiďŹ cant differences.

In the U-14 group, a total of 13 significant correlations (p<0.05) were found. Pearson correlations in the U-14 group ranged from 0.498 to 0.723 and reflect moderate relationships (both positive and negative). DISCUSSION The primary finding of the present study is that the older group (U-16) had higher FMT and jump and/or sprint performance scores compared with younger group (U-14), a finding that is not unexpected given the normal maturation of young athletes. However,

these results may have unique applications for clearing players for sport participation based on requirements to return to a norm-referenced score. Another significant finding of this study was that moderate to strong correlations were detected between certain functional movement and performance tests with the greatest number of correlations identified in the U-14 group. Based on the results of this study, FMT and jump and/or sprint performance test scores should be evaluated based on normative data that are specific to the individual’s age and a greater

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Table 3. Functional movement tests data and between-group comparisons for U-14 and U-16 basketball players. Bolded values represent statistically signiďŹ cant differences.

unipedal stance and monitoring the centre of pressure motion in a force platform unipedal or bipedal, eyes open or eyes shut] and dynamic [SEBT] balance) are apparent both across sports and across performance levels within a given sport. Individual differences in balance ability may relate to individual variations in performance among athletes of differing levels of competitive achievement or the maturation. While such differences, or relationships, cannot infer causation, greater focus on balance training at specific times in athletic development may contribute to successful performance.

Figure 3.

focus on functional movement development among younger athletes is warranted. A review of the literature20 has suggested that differences in balance ability (i.e., static [the timed

The 10-m sprint time (i.e., split time in a 25-m sprint) recorded among basketball players in the current study is similar to professional basketball players aged between 27 to 31 years old as measured in other studies.21,22 According to Schiltz et al.21 professional and junior-level basketball players displayed similar isokinetic knee profiles and functional performances (i.e., bilateral CMJ, bilateral CMJ with arm swing, a 10-m sprint, single-leg drop jump, and

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Table 4. Correlations between functional movement and performance for left limb. Bolded values indicate statistically signiďŹ cant correlations.

Table 5. Correlations between functional movement and performance for right limb.

single-leg 10 s continuous jumping). In the present study, in general, U-16 players demonstrated increased jump and/or sprint performance scores compared with U-14 players. It seems that some

abilities such as sprinting performance (i.e., 10-m sprint time) might be different at younger stages (U-14 vs. U-16), though when the age at peak height velocity (APHV) is achieved and the adolescents

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are in a post-pubertal stage (approximately at 15-16 years) no significant sprinting differences are found. This statement is supported in young soccer players where greater differences are presented between U-14 and U-16 in comparison to U-16 to U-18 in 10-m sprint time.23 However, it is important to note that these differences disappeared when the biological age (APHV) was used as a covariate in the betweengroup comparisons. Thus, sprinting differences might be related to maturational status. In the current study, age appears to be an important factor that may have an impact on associations between FMT and jump and/or sprint performance scores. Anterior excursion data demonstrated various significant relationships to performance measures, primarily in 0-5m, 0-10m, and 0-20m sprint times and horizontal jump. Faster subjects had greater anterior reach. Both left and right excursion scores related to better performance times, demonstrating that greater dynamic ROM relates to increased quickness and acceleration among these elite basketball athletes (U-14). Similarly, Lockie et al.24 found a significant relationship between dynamic stability, as measured by functional reaching, and multidirectional speed (i.e., linear and change of direction speed) in field sport athletes. However, in that study, posterior-lateral and composite excursion data related to slower performance times, demonstrating that greater dynamic ROM was related to decreased acceleration (0-10 m) among these elite basketball athletes (U-16). Gonzalo-Skok et al.14 reported similar results in a similar sample of basketball players. Differences in body size and proportions between U-14 and U-16 could explain the differences in correlations between groups. According to Gribble et al.25 performance on the SEBT varies depending on sport, sex, and age. In addition, the effect of competition level (i.e., high school, collegiate, and professional) on Y-Balance test scores, a variation of the SEBT, in soccer players has been established. In general, professional soccer players exhibited greater dynamic balance during the Y Balance test than did high school soccer players.26 Endo et al.27 reported that lower extremity tightness and balance were significantly correlated in young baseball players. Hoch et al.11 demonstrated a significant proportion of the variance within the anterior reach

distance in this direction of the SEBT may be a good clinical test to assess the effects of dorsiflexion ROM restrictions on dynamic balance. The results from the current study suggest that the better performance in all tests for the U-16 group are based on the maturational status and skill level of these players compared to the younger ones. The lack of significant difference in the CMJ-l might be due to different functional use of left leg (i.e., almost all players were right leg dominant) during basketball skills such as the layup. Furthermore, limitations of the current study should be recognized. The study is inherently limited because it only assessed a small number of elite players in each group and future researchers should determine if similar relationships exist in a larger sample. Data should also be collected on various sports to examine the generalizability of these findings to other athletes beyond basketball. Finally, a greater range in age among study participants would provide more detail regarding the changes in functional movement and performance relationships at different stages of athletic development. In spite of these limitations, the current data suggest that both FMT and performance testing are age-sensitive and can provide the practitioner with useful information regarding performance limitations. CONCLUSIONS The results of this study demonstrated differences in FMT and jump and/or sprint performance test between age groups (U-16 vs U-14). The findings of this study support the idea that the age of the player should be considered when interpreting FMT scores, which could have implications when implementing the FMT for injury risk prediction. REFERENCES 1. Ben Abdelkrim N, El Fazaa S, El Ati J. Time-motion analysis and physiological data of elite under-19year-old basketball players during competition. Br J Sports Med. 2007;41(2):69-75. 2. Gabbett T, King T, Jenkins D. Applied physiology of rugby league. Sports Med. 2008;38(2):119-138. 3. Chaouachi A, Brughelli M, Chamari K, et al. Lower limb maximal dynamic strength and agility determinants in elite basketball players. J Strength Cond Res. 2009;23(5):1570-1577.

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4. Ben Abdelkrim N, Castagna C, Jabri I, Battikh T, El Fazaa S, El Ati J. Activity profile and physiological requirements of junior elite basketball players in relation to aerobic-anaerobic fitness. J Strength Cond Res. 2010;24(9):2330-2342. 5. Ziv G, Lidor R. Vertical jump in female and male basketball players--a review of observational and experimental studies. J Sci Med Sport. 2010;13(3):332339. 6. Faude O, Koch T, Meyer T. Straight sprinting is the most frequent action in goal situations in professional football. J Sports Sci. 2012;30(7):625-631. 7. Ben Abdelkrim N, Castagna C, El Fazaa S, El Ati J. The effect of players’ standard and tactical strategy on game demands in men’s basketball. J Strength Cond Res. 2010;24(10):2652-2662. 8. Backman LJ, Danielson P. Low range of ankle dorsiflexion predisposes for patellar tendinopathy in junior elite basketball players: a 1-year prospective study. Am J Sports Med. 2011;39(12):2626-2633. 9. Clagg S, Paterno MV, Hewett TE, Schmitt LC. Performance on the modified star excursion balance test at the time of return to sport following anterior cruciate ligament reconstruction. J Orthop Sports Phys Ther. 2015;45(6):444-452. 10. Plisky PJ, Rauh MJ, Kaminski TW, Underwood FB. Star Excursion Balance Test as a predictor of lower extremity injury in high school basketball players. J Orthop Sports Phys Ther. 2006;36(12):911-919. 11. Hoch MC, McKeon PO. Normative range of weightbearing lunge test performance asymmetry in healthy adults. Man Ther. 2011;16(5):516-519. 12. Gustavsson A, Neeter C, Thomee P, et al. A test battery for evaluating hop performance in patients with an ACL injury and patients who have undergone ACL reconstruction. Knee Surg Sports Traumatol Arthrosc. 2006;14(8):778-788. 13. Lockie RG, Callaghan SJ, Berry SP, et al. Relationship between unilateral jumping ability and asymmetry on multidirectional speed in team-sport athletes. J Strength Cond Res. 2014;28(12):3557-3566. 14. Gonzalo-Skok O, Serna J, Rhea MR, Marin PJ. Relationships between Functional Movement Tests and Performance Tests in Young Elite Male Basketball Players. Int J Sports Phys Ther. 2015;10(5):628-638. 15. Calatayud J, Martin F, Gargallo P, Garcia-Redondo J, Colado JC, Marin PJ. The validity and reliability of a new instrumented device for measuring ankle dorsiflexion range of motion. Int J Sports Phys Ther. 2015;10(2):197-202.

16. Attia A, Dhahbi W, Chaouachi A, Padulo J, Wong DP, Chamari K. Measurement errors when estimating the vertical jump height with flight time using photocell devices: the example of Optojump. Biol Sport. 2017;34(1):63-70. 17. Glatthorn JF, Gouge S, Nussbaumer S, Stauffacher S, Impellizzeri FM, Maffiuletti NA. Validity and reliability of Optojump photoelectric cells for estimating vertical jump height. J Strength Cond Res. 2011;25(2):556-560. 18. Gonzalo-Skok O, Tous-Fajardo J, Suarez-Arrones L, Arjol-Serrano JL, Casajus JA, Mendez-Villanueva A. Validity of the V-cut Test for Young Basketball Players. Int J Sports Med. 2015;36(11):893-899. 19. Hopkins WG, Marshall SW, Batterham AM, Hanin J. Progressive statistics for studies in sports medicine and exercise science. Med Sci Sports Exerc. 2009;41(1):3-13. 20. Hrysomallis C. Balance ability and athletic performance. Sports Med. 2011;41(3):221-232. 21. Schiltz M, Lehance C, Maquet D, Bury T, Crielaard JM, Croisier JL. Explosive strength imbalances in professional basketball players. J Athl Train. 2009;44(1):39-47. 22. Shalfawi SA, Sabbah A, Kailani G, Tonnessen E, Enoksen E. The relationship between running speed and measures of vertical jump in professional basketball players: a field-test approach. J Strength Cond Res. 2011;25(11):3088-3092. 23. Mendez-Villanueva A, Buchheit M, Kuitunen S, Douglas A, Peltola E, Bourdon. Age-related differences in acceleration, maximum running speed, and repeated-sprint performance in young soccer players. J Sports Sci. 2011;29(5):477-84. 24. Lockie RG, Schultz AB, Callaghan SJ, Jeffriess MD. The Relationship between Dynamic Stability and Multidirectional Speed. J Strength Cond Res. 2013. 25. Gribble PA, Hertel J, Plisky P. Using the Star Excursion Balance Test to assess dynamic posturalcontrol deficits and outcomes in lower extremity injury: a literature and systematic review. J Athl Train. 2012;47(3):339-357. 26. Butler RJ, Southers C, Gorman PP, Kiesel KB, Plisky PJ. Differences in soccer players’ dynamic balance across levels of competition. J Athl Train. 2012;47(6):616-620. 27. Endo Y, Sakamoto M. Relationship between lower extremity tightness and star excursion balance test performance in junior high school baseball players. J Phys Ther Sci. 2014;26(5):661-663.

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IJSPT

ORIGINAL RESEARCH

INJURY PATTERNS IN ADOLESCENT ELITE ENDURANCE ATHLETES PARTICIPATING IN RUNNING, ORIENTEERING, AND CROSS-COUNTRY SKIING Philip von Rosen, Ph.D1 Frida Floström, M.Sc1,2 Anna Frohm, Ph.D1,2 Annette Heijne, Ph.D1

ABSTRACT Background: Prospective injury registration studies, monitoring adolescent elite athletes, are sparse in running, orienteering and cross-country skiing, yet essential for developing prevention programs. Purpose: The aims of this study were to describe the injury prevalence/incidence, severity grade, injury location, risk factors and the prevalence of illness in running (RU), orienteering (OR) and cross-country skiing athletes (CR). Study Design: Prospective cohort study. Methods: One hundred fifty adolescent elite athletes (age range 16-19), participating in orienteering (25 females, 20 males), running (13 females, 18 males), cross-country skiing (38 females, 36 males), from 12 National Sports High Schools in Sweden, were prospectively followed over one calendar year using a reliable and validated web-based questionnaire. Results: The main finding was that the average weekly injury prevalence was higher during the pre-season compared to the competitive season in all three sports. RU reported the significantly (p<0.05) highest average weekly injury prevalence (32.4%) and substantial injury prevalence (17.0%), compared to OR (26.0, 8.2%) and CR (21.1%, 8.9%). Most injuries occurred in the lower extremity (RU 94.4%; OR 91.9%; CR 49.9%) and foot and knee injuries had the highest severity grade in all three sports. History of serious injury (p=0.002, OR 4.0, 95% CI 1.6-9.7) and current injury at study start (p=0.004, OR 4.0, 95% CI 1.5-11.2) were identified as the strongest risk factors for substantial injury. Younger athletes aged 16 (p=0.019, OR 2.6, 95% CI 1.2-5.8) and 17 (p=0.045, OR 2.4, 95% CI 1.0-5.9), had a significantly higher injury risk for substantial injury compared to older athletes aged 18-19. Conclusion: Practitioners should be aware of the increased injury risk during pre-season and in younger athletes. By focus on prevention of foot and knee injuries, the injuries with the highest severity grade will be targeted in adolescent elite athletes participating in running, orienteering and cross-country skiing. Level of evidence: 2b Key words: athletics, elite sports, injury burden, youth

1

Karolinska Institutet, Department of Neurobiology, Care Sciences, and Society (NVS), Division of Physiotherapy, Huddinge, Sweden 2 Swedish Sports Confederation Centre, Bosön SportsClinic, Lidingö, Sweden Acknowledgement We would like to express our gratitude to all athletes participating in the study. Funding This work was supported by the Swedish National Centre for Research in Sports under Grant FO2016-0009. No direct or indirect financial supports have occurred from the direct applications of this research project.

CORRESPONDING AUTHOR Philip von Rosen, PhD, Division of Physiotherapy, NVS, Karolinska Institutet, Alfred Nobels Allé 23, SE-141 83 Huddinge, Sweden. Phone: +46–8-524 888 37 E-mail address: philip.von.rosen@ki.se

The International Journal of Sports Physical Therapy | Volume 12, Number 5 | October 2017 | Page 822 DOI: 10.16603/ijspt20170822

INTRODUCTION The training sessions in endurance sports are often of long duration involving repetitive movements, likely contributing to the high risk of overuse injuries.1-3 By identifying the injury incidence and prevalence as well as associated risk factors and injury mechanisms in sports, effective injury prevention programs can be designed, aiming to reduce the risk for injuries and unhealthy behaviors. Despite the value of injury surveillance studies, few reports have included youth athletes and especially adolescent elite athletes.4 The knowledge of the injury incidence and prevalence in this age group (age 13-19) is limited and in most sports unknown. This study focuses on exploring injury patterns in adolescent elite athletes participating in running, orienteering, and cross-country skiing. Although running, orienteering, and cross-country skiing have a long history, few prospective studies on injury occurrence are available in the scientific literature. Instead, most reports are point prevalence studies based on data collected during competitions and championships.5-9 Such data is not representative of an entire season, covering both preseason and competition periods. Long-term prospective reports in running are sparse, especially following young running athletes (RU) over an entire season. Rauh et al.10 monitored high school cross-country runners over a 15-year period and found an overall injury rate of 13.1/1000 training sessions/competitions. Most running injuries occur in the lower extremity11 and the incidence of severe injuries, such as stress fractures, have been found to be high.12 In a one-year prospective study by Jacobsson et al,13 following track & field athletes, including middle- and long-distance runners, more than 50% of all injuries were severe in nature resulting in at least three weeks absence from normal training. Different risk factors for a running injury have been implicated, such as a high training volume, history of previous injury as well as a higher overall injury risk in female runners compared to male runners.2,11,14,15 Still, these studies are mainly based on adult runners. In cross-country skiing the athletes complete races over courses of varying lengths using mainly two

type of skiing styles, classic or skate. Cross-country skiing athletes (CR) are traditionally considered as having low-risk for severe injuries.16, 17 However, low back pain has been proposed as a severe injury in this group of athletes,17-19 whereas other reports have shown the injury severity to be higher in the lower extremity, including knee and anterior thigh injuries.2, 16 Few reports have monitored CR prospectively over a complete season. In a retrospective study, Ristolainen et al.2 identified the overall injury incidence rate to 2.1/1000 hours of exposure in elite cross-country skiing athletes aged 15-35 years. Orienteering athletes (OR) must run through tough terrain and at the same time making route choices, in order to complete the course as fast as possible. Both prospective3,8 as well as cross-sectional studies6,9 have identified injuries to most often occur in the lower extremity. Von Rosen et al.3 followed 64 adolescent elite OR over 26 weeks and the incidence rate was 18 injuries/1000 hours of training with an average weekly prevalence of 18% for severe injuries. The high incidence rate is likely influenced by the injury definition of including all kinds of physical complaints. No difference between injured male and female athletes was found. The incidence of injuries seems to be higher in OR3 compared to CR and TR.2,16 However, different injury definitions and surveillance periods have been used, making study comparisons difficult. In summary, prospective reports monitoring adolescent elite athletes over a complete season are sparse in orienteering, running and cross-country skiing, yet essential for development of injury prevention programs. The aims of this study were to describe the injury prevalence/incidence, severity grade, injury location, risk factors and the prevalence of illness in RU, OR and CR. METHODS Data collection The National Federations of Orienteering, Track & Field, and Skiing were invited to a physical information meeting about the KASIP-study (Karolinska Athlete Screening Injury Prevention). After the meeting, the three National Federations of Sports agreed to participate and twelve Swedish National

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Sports High Schools were invited to participate. One of the authors visited each school to inform the athletes and their coaches about the purpose of the study and the voluntary nature of participation. By definition, all adolescent athletes studying at National High Sports Schools are elite athletes because their sport performance results were of such a standard that allowed entry. To attend these schools athletes need to be among the top in terms of ranking in their age group for respective sporting events on national level. A running athlete was defined as an athlete participating in 800-10 000 meter events. A total of 224 athletes (age range 16-19) were then invited by e-mail and 189 athletes (84.4%) responded to the invitation. Written consent was obtained from all athletes. A questionnaire was e-mailed to all athletes weekly over one calendar year, consecutively starting between September and December 2013, using the software; Questback online survey (Questback V. 9.9, Questback AS, Oslo, Norway). Athletes that did not respond to the questionnaire received an e-mail reminder four days later. An online background questionnaire was also distributed to the athletes during the first week of the study. In order to provide a valid picture of the injury burden over a complete season, keep a constant response rate and avoid a biased result based on occasional

responders during the first five weeks, in line with Clarsen et al.,20 a total of 39 athletes were excluded from the analysis (n = 6 due to missing background data, n =33 due to less than 10% response rate) (Figure 1). The excluded athletes were equally distributed among the three sports (p=0.368). The final cohort therefore consisted of 150 adolescent elite athletes (female = 74, male = 76), median 17 years (range 16-19) and included 67.0% of the initial selection of athletes (Figure 1). This study is approved by the Regional Ethical Committee in Sweden (No: X). Questionnaires The weekly distributed questionnaire was based on the reliable and validated version of the OSTRC (Oslo Sports Trauma Research Centre) Overuse Injury Questionnaire,21 previously used in multiple sports studies,3, 16, 20 as well as questions about new injuries used by Jacobsson et al.13 in a track & field surveillance study. OSTRC Overuse Injury Questionnaire quantifies injury consequences on sports participation, performance, training and pain based on four questions with alternative responses.21 It assesses injuries effect on participation (four alternative responses from ”full participation” to ”cannot participate”), reduction in training volume (five alternative responses from ”no reduction” to ”cannot participate”), reduced sporting performance (five alternative responses from ”no effect” to ”cannot participate”) and experience of pain (four alternative

Figure 1. Flowchart of participant enrollment. f= female; m= male. The International Journal of Sports Physical Therapy | Volume 12, Number 5 | October 2017 | Page 824

responses from ”no pain” to ”severe pain”). In addition, athletes were asked to report all performed training and competition time in hours/week. The completion of the questionnaire took approximately five minutes. Operational definitions All injury data were self-reported and the athletes were asked to report an injury as any physical complaint that affected participation in normal training or competition, led to reduced training volume, experience of pain or reduced performance in sports.21 A substantial injury was defined as an injury leading to moderate or severe reductions in training volume, or moderate or severe reduction in performance, or complete inability to participate in sports.21 A new injury was categorized as a recurrent or a non-recurrent injury, based on if the injury occurred in the same body site as the previous injury within the last year. Illness was defined as a self-reported health problem other than the musculoskeletal system, such as cold, influenza etc., resulting in reduced training volume or difficulties participating in normal training or competition. A complete season refers to the time athletes were followed, including both pre-season and competitive season. Based on occurrence of main competitions, the competitive season for CR was defined as started from beginning of November to end of March, for OR as beginning of May to end of September and for RU as beginning of May to middle of September. This resulted in follow up periods for running, orienteering, cross-country skiing of 20/32, 27/25, 23/29 weeks for pre-season/competitive season, respectively. STATISTICAL METHODS Descriptive statistics for continuous variables are presented as mean and standard deviation (SD), for nonnormally distributed or ordinal data as median with 25th–75th percentiles (p25–p75), and as frequency and proportion (%) for categorical data. The response rate, prevalence and incidence measures of injury were determined and ninety-five percent confidence intervals (95% CI) were computed for these measures. Prevalence of injury, injury consequences and illness was calculated by dividing the number of

athletes reporting injury, illness or injury consequences, by the number of respondents for each week. The average weekly injury prevalence, substantial injury prevalence, injury consequences prevalence and illnesses prevalence over one calendar year, were determined. The incidence rate of injuries was estimated by summing all new injuries per 1000 hours of exposure to sports. The injury incidence was determined by taking the proportion of athletes reporting a new injury for each week. The average value was used. The average response rate was calculated by dividing the number of respondents with the total number of athletes for each week and taken the average number of these values. The prevalence of injury was determined for the pre-season and competitive season. A severity score was determined, by allocating a numerical value from 0 to 25 to the responses in the four questions in the OSTRC Overuse Injury Questionnaire.21 The four questions were then summed. Consequently, a score of 0 represents no injury and 100 the highest level of severity. To demonstrate the relative impact of injuries in each body site the severity grade was calculated by summing athletes’ severity scores over one calendar year for each body site and dividing the sum with the total number of respondents. The severity grade can be described as a measure of the consequences of injuries on sports participation, training, performance and pain, adjusted for different group sizes and response rates in each sport. Please see Clarsen et al.21 for additional information about the calculation of severity grade. The injury risk for substantial injury in the three sports overall were calculated using the Pearson’s chi-square test. The risk factors included were sport types, sex, age, history of serious injury, injury at study start, number of rest days/week and number of training sessions/week. Number of rest days/week and number of training sessions/week were dichotomized at the 50% percentile, i.e. ≥3 rest days/week, ≥7 training sessions/week. Odds ratios were calculated for each risk factor. Throughout calculations, the significance level was set to P < .05. All analyses were performed using the SPSS software for Windows, version 22.0 (SPSS, Evanston, IL) and Microsoft Excel software (Excel 2013; Microsoft Corp, Redmond, WA).

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RESULTS Demographics and response rate In average, the orienteering athletes (OR) had a training volume of 7.1 (SD 3.0), running athletes (RU) 8.3 (SD 3.6) and cross-country skiers (CR) 9.8 (SD 4.7) hours per week. At the start of the study, 33.3% (n=15) of the OR and 35.5% (n=11) of the RU were injured, compared to 10.8% (n=8) of the CR. In CR, 20.3% (n=15) reported to have sustained a serious injury the previous year that partly or completely hindered training for at least three weeks, compared to 37.8% (n=17) and 41.9% (n=13) in OR and RU, respectively. Injury incidence and prevalence of injury and illness OR had a significantly (p<0.05) higher injury incidence rate (5.7 injuries/1000 hours exposure to sports, 95% CI 4.2-7.1) compared to CR (2.5 injuries/1000 hours exposure to sports, 95% CI 1.8-3.1) (Table 1). The prevalence of injury was significantly (p<0.05) higher during the pre-season compared to the competitive season in each sport (Figure 2). The average weekly injury prevalence, average weekly substantial injury prevalence were significantly (p<0.05) higher in RU, than for OR and CR. Male RU had a significantly (p<0.05) higher average weekly injury prevalence (39.3%) and substantial injury prevalence (23.2%) compared to female RU

(21.9%; 8.2%), whereas in CR, female athletes had a significantly (p<0.05) higher average weekly injury prevalence (26.6%) and substantial injury prevalence (11.1%), compared to male athletes (14.1%; 5.9%). The prevalence of illness was equally distributed in each sport (range 14.0-15.0%) and no significant (p<0.05) difference between sexes was found within sports. The most common illnesses in all three sports were cold and flu. Injury location The majority of injuries occurred in the lower extremity, however, the proportion varied in each sport. In OR, 91.9% (n=56) were located in the lower extremity, mainly the foot (39.3%, n=24), knee (23.0%, n=14) and the lower leg (13.1%, n=8). In RU, 94.4% (n=34) of all injuries were located in the lower extremity, 2.8% (n=1) in the lower back and 2.8% (n=1) in the shoulder. In CR, 49.9% (n=29) of all injuries were located in the lower extremity, 15.5% (n=9) in the lower back, 12.1% (n=7) in the shoulder and 8.6% (n=5) in the hand. Injury risk and severity grade A total of 155 unique new injuries were identified, including 41 recurrent injuries (26.5%). History of serious injury (p=0.002, OR 4.0) and current injury at study start (p=0.004, OR 4.0) were identified as the strongest risk factors for substantial injury

Table 1. Demographics of orienteering, running and cross-country skiing athletes.

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Figure 2. The prevalence of injury showed bi-weekly over the 52 week study period (• indicate the competitive season for each sport) with the average injury prevalence for the pre-season (Pre) and competitive season (Com).

DISCUSSION This is one of the first prospective cohort studies presenting and comparing injury data in endurance sports of adolescent elite athletes, collected over one calendar year. The main finding was that the average weekly injury prevalence was higher during

the pre-season compared to the competitive season. Three risk factors were identified; having a history of serious injury, having an injury at the start of the study, and being 16-17 years old as compared to the 18-19 year old athletes. Most injuries

as well as the injuries with the highest severity grade occurred in the lower extremity, mainly the foot and the knee, which calls for prevention programs targeting these regions.

Figure 3. Relative impact of injuries by sport (RU= running athletes; OR= orienteering athletes; CR= cross-country skiing athletes). Shown as top ďŹ ve highest relative impact per body site for each sport.

(Table 4). Younger athletes of age 16 (p=0.019, OR 2.6) and 17 (p=0.045, OR 2.4) had a significantly higher injury risk for substantial injury compared to older athletes of age 18-19. The injuries that caused the highest severity grade were mainly located in the foot and the knee region in all the three sports (Figure 2).

The findings support the concept that a previous or current injury could increase the risk of a severe injury,22,23 in adolescent elite athletes participating in endurance sports. In contrast to Ristolainen et al.,24 number of rest days or number of training sessions per week did not affect the injury risk. This may be due to different study-designs (prospective vs. retrospective) or sample characteristics, such as including adult athletes in Ristolainen et al. That younger athletes had a higher injury risk than older athletes in endurance sports may be related to the increased pressure, competiveness, or training load occurring during the first years in National Sports High Schools. Although injury risk has been found to be high during competition in track & field event5,25,26 or orienteering,9 the injury risk was found to be higher during pre-season compared to the

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Table 2. The injury incidence rate, the average weekly injury incidence and injury prevalence data and illness presented for all athletes and by sex in each sports (95% CI in parentheses).

Table 3. Number of injuries (%) per sport.

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Table 4. Overall risk for substantial injury, showed with odds ratio (OR) and corresponding 95% conďŹ dence interval (95% CI).

competitive season in all three endurance sports and markedly higher during pre-season in orienteering. This finding supports the results from Rauh et al.,14 showing that runners had a higher injury risk during pre-season, possibly explained by the long training sessions or high training volume endured during pre-season in endurance sports.24 The training variation may be less pronounced during pre-season, compared to the competitive season. Although the three sports included have similar characteristics with athletes undertaking high training loads, there were clear differences in injury patterns in terms of injury and substantial injury prevalence, discussed below. Since, running is part of the umbrella term track & field, many authors have previously reported longitudinal injury data for track & field athletes overall, instead of per athletic event category. This makes it hard to compare the data to the cohort of runners. However, the existing studies have shown that runners, at least during competitions, may have a higher injury risk compared to other disciplines of track & field.5,25,26 In line with a systematic review of long-distance runners by van Gent et al.,11 most injuries occurred in the lower extremity, which were also the region with the highest injury severity grade. No significant sex differences of injury

incidence in RU was found, in line with Bennell & Crossley12 and Alonso et al.,26 but contrary to Alonso et al.5, 25 and Jacobsson et al.13,27 The use of different injury definitions, study designs and study period may explain the diversity between studies. For example, in Alonso et al.5 athletes were only followed over specific championships, whereas in Bennell & Crossley12 and Jacobsson et al.,13 athletes were closely monitored during one year. However, there was a significant difference in the average injury prevalence and substantial prevalence, illustrating a higher injury burden in male RU compared to female RU. Only two reports, using relatively small samples, have followed OR prospectively.3,8 Linde8 monitored OR monthly, whereas in von Rosen et al.,3 OR were weekly monitored during 26 weeks. In line with these two reports, the majority of injuries in elite OR occurred in the lower extremity, mainly the foot, lower leg and the knee. A similar distribution of injury locations identified in this report, has been found in middle- and long-distance runners,10,14 illustrating comparable injury patterns in athletes of running and orienteering. High training volume on uneven surfaces has been proposed as an explanation to the high occurrence of injuries in the lower extremity.28 Linde8 found that most injuries were

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ankle sprains. In this study, foot and knee injuries caused the highest severity grade of all injuries. Female OR had a higher overall injury incidence rate (6.6 injuries/1000 hours exposure to sports) and injury prevalence (31.7%) compared to male athletes (4.6 injuries/1000 hours exposure to sports, 18.9%). In summary, the prevalence of injuries was high in OR, but not as high as in RU. The average weekly injury prevalence and injury incidence was lower in CR compared to RU and OR. A low injury incidence in youth elite CR is in concordance with reports of adult elite CR.17 Sex differences are limitedly reported in this sport and the few published studies have shown conflicting results. For instance, no sex differences regarding injury incidence rates occurred in World Cup CR,17 whereas in one report neck pain was found to be more common in female compared to male CR.18 In this report, female athletes reported a higher prevalence of injury (26.6%) and substantial injury (11.1%) compared to male athletes (14.1%, 5.9%). The difference between studies may be explained by different study-designs or definition of injury. According to previous authors, low back pain is a common musculoskeletal disorder in CR.18,29 In this report, the incidence as well as the severity grade of lower back injury was higher in CR compared to OR and RU. However, considering the incidence and the severity grade of foot injuries in CR, foot injuries should be the first priority, with low back pain a secondary priority, when designing prevention programs for this cohort. With regard to illness, endurance athletes are believed to have an increased susceptibility to infections due to a high training load.30 Even though the prevalence of illness is rarely reported in prospective reports, the incidence of illness has shown to increase during championships and during intense period of competitions.31 In this report the prevalence of illness was equally distributed in CR (14.6%), RU (14.0%) and OR (15.0%), probably related to similar training and competition load in these three sports. Interestingly, at the start of the study both a higher proportion of RU were injured and had a history of a severe injury compared to OR and CR. When analyzing the injury data on an individual level, the

occurrence of injuries was not only associated with occurrence of new injuries but also related to injuries occurring prior to the start of the study. Of all athletes, 10% (n=22) started the study reporting the same injury for at least ten of the first fifteen weeks. Directing action towards prevention of new injuries is a priority, but it may be as important to fully rehabilitate injured athletes and delay return to sports participation until that time. Health practitioners should therefore pay attention and treat early injury symptoms to prevent long-term injuries. In addition, preventive actions should be based on injury prevalence and severity as well as incidence. Finally, by focusing on foot and knee injuries in CR, OR and RU, the injuries with the highest incidence and most serious consequences will be targeted in these sports. The strength of this study is the long study period, in which athletes with similar characteristics from three different sports were followed weekly over one calendar year including a complete season. The twelve schools included are located all over Sweden and include all available athletes in these three sports studying on National Sports High Schools. Therefore, the athletes could be defined as a homogeneous group, characterised by elite athletes competing at the highest national level of their age group. The questionnaire used is valid, reliable and has been repeatedly used in a sport context during recent years.13,21 In addition, a broad spectrum of injury patterns was recorded, including injury incidence/prevalence, severity grade and injury risk factors. No attempt was made to classify injuries based on e.g. ICD-10, since correctly classified injuries require diagnosis by trained medical staff.32 It must also be recognized that this study has limitations. Following athletes during a complete year requires patience and persistence by the athletes. Due to the present respondent fatigue the prevalence and incidence data may be underestimated.16 However, this phenomenon did not affect the results in terms of occurrence of substantial injuries, in concordance with previous reports.3,21 Based on Clarsen et al.20 athletes with a response rate of less than 10% were excluded. The analysis of the demographics of the excluded athletes showed no differences regarding sports participation compared to the main

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cohort. The response rate was in line with Clarsen at al.20 and no significant difference was found between sports. The risk factor analysis was determined only for substantial injury, since this injury definition is leading to great consequences on sports participation, training and performance level. Further on, the risk factors were calculated for endurance athletes overall, since the power was too limited to detect sport specific risk factors. CONCLUSION This is one of the first prospective cohort studies comparing injury data, collected weekly over a complete season, in adolescent elite athletes participating in running, orienteering and cross-country skiing. The main finding was that the average weekly injury

prevalence was higher during the pre-season compared to the competitive season in all three sports. RU had a higher average weekly injury prevalence and substantial injury prevalence compared to OR and CR. Athletes who had history of serious injury, who started the study with an injury or who were 16-17 years old were identified as having a higher risk of injury. Practitioners should be aware of increased injury risk during pre-season and focus on prevention of foot and knee injuries to target the severe injuries with greatest prevalence in these sports. REFERENCES 1. Knobloch K, Yoon U, Vogt PM. Acute and overuse injuries correlated to hours of training in master running athletes. Foot Ankle Int. 2008;29:671-676. 2. Ristolainen L, Heinonen A, Turunen H, et al. Type of sport is related to injury profile: a study on cross country skiers, swimmers, long-distance runners and soccer players. A retrospective 12-month study. Scand J Med Sci Sports. 2010;20:384-393. 3 von Rosen P, Heijne AI, Frohm A. Injuries and associated risk factors among adolescent elite orienteerers: a 26-Week prospective registration study. J Athl Train. 2016;51:321-328. 4. Steffen K, Engebretsen L. More data needed on injury risk among young elite athletes. Br J Sports Med. 2010;44:485-489. 5. Alonso JM, Tscholl PM, Engebretsen L, et al. Occurrence of injuries and illnesses during the 2009 IAAF World Athletics Championships. Br J Sports Med. 2010;44:1100-1105. 6. Ekstrand J, Roos H, Tropp H. The incidence of ankle sprain in orienteering. Sci J Orienteer. 1990;6:3-9.

7. Junge A, Engebretsen L, Mountjoy ML, et al. Sports injuries during the Summer Olympic Games 2008. Am J Sports Med. 2009;37:2165-2172. 8. Linde F. Injuries in orienteering. Br J Sports Med. 1986;20:125-127. 9. Linko PE, Blomberg HK, Frilander HM. Orienteering competition injuries: injuries incurred in the Finnish Jukola and Venla relay competitions. Br J Sports Med. 1997;31:205-208. 10. Rauh MJ, Margherita AJ, Rice SG, et al. High school cross country running injuries: a longitudinal study. Clin J Sport Med. 2000;10:110-116. 11. van Gent RN, Siem D, van Middelkoop M, et al. Incidence and determinants of lower extremity running injuries in long distance runners: a systematic review. Br J Sports Med. 2007;41:469-480. 12. Bennell KL, Crossley K. Musculoskeletal injuries in track and field: incidence, distribution and risk factors. Aust J Sci Med Sport. 1996;28:69-75. 13. Jacobsson J, Timpka T, Kowalski J, et al. Injury patterns in Swedish elite athletics: annual incidence, injury types and risk factors. Br J Sports Med. 2013;47:941-952. 14. Rauh MJ, Koepsell TD, Rivara FP, et al. Epidemiology of musculoskeletal injuries among high school crosscountry runners. Am J Epidemiol. 2006;163:151-159. 15. van der Worp MP, ten Haaf DS, van Cingel R, et al. Injuries in runners; a systematic review on risk factors and sex differences. PLoS One. 2015;10:e0114937. 16. Clarsen B, Bahr R, Heymans MW, et al. The prevalence and impact of overuse injuries in five Norwegian sports: Application of a new surveillance method. Scand J Med Sci Sports. 2015;25:323-330. 17. Flørenes TW, Heir S, Nordsletten L, et al. Injuries among World Cup freestyle skiers. Br J Sports Med. 2010;44:803-808. 18. Bergstrøm KA, Brandseth K, Fretheim S, et al. Back injuries and pain in adolescents attending a ski high school. Knee Surg Sports Traumatol Arthrosc. 2004;12:80-85. 19. Foss IS, Holme I, Bahr R. The prevalence of low back pain among former elite cross-country skiers, rowers, orienteerers, and nonathletes: a 10-year cohort study. Am J Sports Med. 2012;40:2610-2616. 20. Clarsen B, Bahr R, Andersson SH, et al. Reduced glenohumeral rotation, external rotation weakness and scapular dyskinesis are risk factors for shoulder injuries among elite male handball players: a prospective cohort study. Br J Sports Med. 2014;48:1327-1333.

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21. Clarsen B, Myklebust G, Bahr R. Development and validation of a new method for the registration of overuse injuries in sports injury epidemiology: the Oslo Sports Trauma Research Centre (OSTRC) overuse injury questionnaire. Br J Sports Med. 2013;47:495-502. 22. Chomiak J, Junge A, Peterson L, Dvorak J. Severe injuries in football players. Influencing factors. Am J Sports Med. 2000;28: S58-S68. 23. Waldén M, Hägglund M, Ekstrand J. Injuries in Swedish elite football--a prospective study on injury definitions, risk for injury and injury pattern during 2001. Scand J Med Sci Sports. 2005;15:118-125. 24. Ristolainen L, Kettunen JA, Waller B, et al. Trainingrelated risk factors in the etiology of overuse injuries in endurance sports. J Sports Med Phys Fitness. 2014;54:78-87. 25. Alonso JM, Junge A, Renström P, et al. Sports injuries surveillance during the 2007 IAAF World Athletics Championships. Clin J Sport Med. 2009;19:26-32. 26. Alonso JM, Edouard P, Fischetto G, et al. Determination of future prevention strategies in elite track and field: analysis of Daegu 2011 IAAF

Championships injuries and illnesses surveillance. Br J Sports Med. 2012;46:505-514. 27. Jacobsson J, Timpka T, Kowalski J, et al. Prevalence of musculoskeletal injuries in Swedish elite track and field athletes. Am J Sports Med. 2012;40:163-169. 28. Creagh U, Reilly T. Physiological and biomechanical aspects of orienteering. Sports Med. 1997;24:409-418. 29. Alricsson M, Werner S. Self-reported health, physical activity and prevalence of complaints in elite cross-country skiers and matched controls. J Sports Med Phys Fitness. 2005;45:547-552. 30. Engebretsen L, Steffen K, Alonso JM, et al. Sports injuries and illnesses during the Winter Olympic Games 2010. Br J Sports Med. 2010;44:772-780. 31. Soligard T, Steffen K, Palmer-Green D, et al. Sports injuries and illnesses in the Sochi 2014 Olympic Winter Games. Br J Sports Med. 2015;49:441-447. 32. Timpka T, Alonso JM, Jacobsson J, et al. Injury and illness definitions and data collection procedures for use in epidemiological studies in Athletics (track and field): consensus statement. Br J Sports Med. 2014;48:483-490.

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IJSPT

ORIGINAL RESEARCH

INJURIES IN QUIDDITCH: A DESCRIPTIVE EPIDEMIOLOGICAL STUDY Rachel Pennington1 Ashley Cooper2 Evan Edmond3 Alastair Faulkner4 Michael J Reidy4 Peter S E Davies4

ABSTRACT Background: Quidditch is a fast growing, physically intense, mixed-gender full-contact sport. Originally adapted from Harry Potter novels, quidditch was first played in 2005 in the USA but is now played worldwide. It is essential to elucidate patterns of injury for the safety and growth of the sport of quidditch. It also provides a unique opportunity to study injury patterns in mixed-gender full-contact sport, an area of increasing importance with the developing culture of transition from single-gender to mixed-gender sports. Purpose: The purpose of this investigation was to examine the types of injuries sustained while playing quidditch in terms of their incidence, anatomical distribution and severity, and gender distribution. Methods: An anonymous self-reporting questionnaire was distributed to all active quidditch players in the UK. Data collection included player demographics, type of injury, mechanism of injury, player position, experience and treatment required, relating to the previous 12 months. Results: A total of 348 participants of 684 eligible athletes responded to the questionnaire representing a 50.87% response rate. There were 315 injuries reported by 180 athletes in total, with an overall incidence of 4.06 injuries per 1,000 hours. A statistically significantly different rate of concussion was observed with female athletes sustaining more concussion than males (p=0.006). The overall rate of concussion was 0.651/1000hrs in males and 1.163/1000hrs in females (0.877/1000 hours overall). Conclusions: This study provides the first quantitative description of injury rates in quidditch. The overall injury rates are no higher than those reported in other recreational contact sports. Female athletes were found to have a higher rate of concussion, which needs further investigation. These findings are relevant to players concerned about safety in quidditch and to governing bodies regarding governance of the sport. Level of Evidence: 3b Key words: Concussion, descriptive epidemiological study, fracture, Harry Potter, injury, quidditch

1

University of Edinburgh Medical School, Edinburgh, Scotland Manchester Royal InďŹ rmary, Central Manchester Foundation Trust, Manchester, UK 3 John Radcliffe Hospital, Oxford, UK 4 Department of Trauma and Orthopaedics, Ninewells Hospital, Dundee, UK 2

CORRESPONDING AUTHOR Peter S E Davies Department of Trauma and Orthopaedics, Ninewells Hospital, Dundee, DD21UB +447412562140 E-mail: petersedavies@doctors.org.uk

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INTRODUCTION The real-life sport of quidditch was first adapted from JK Rowling’s Harry Potter novels in 2005 in the USA.1 Since then, it has grown vastly in popularity involving approximately 20,000 players in 25 countries across the world, including the UK, Australia, Brazil, Uganda and Korea.2,3 So far there have been three quidditch World Cups held by the International Quidditch Association, where national teams can compete at an international level. Within the UK, the annual British Quidditch Cup is the largest and most prestigious UK tournament with the 32 best UK teams competing, having qualified from their respective regional tournaments.4 Summer 2017 marked the launch of the Quidditch Premier League, whereby eight regional teams will battle for the title of quidditch UK champion.5 Rules are largely based on the fictional game: Three “chasers” try to score past one “keeper” by throwing the “quaffle” (a slightly soft volleyball) through any of the three opposing team’s hoops for 10 points. Meanwhile, two “beaters” attack opposing players with one of three “bludgers” (dodge balls), which temporarily knock a player out of the game if hit. The final ball is the “snitch”, which consists of a human runner shielding a tennis ball in a sock hanging from the back of their shorts. 6 An award of 30 points is made to the team whose “seeker” is able to catch the snitch. Catching the snitch also ends the game. There are therefore two teams of seven people and up to five balls in play at any one time. Substitutions can be made at any time during the game and players can switch positions by being substituted out of the game and swapping headbands (the colors of which are used to designate player roles). The likeness continues even down to the athletes carrying ‘broomsticks’ (PVC pipes) between their thighs at all times. Competitive sports are based on a handicap that defines it (e.g. one must pass backwards in rugby) and for quidditch this is the use of a broomstick. Unlike the fictional game, players are unable to elevate themselves into the air therefore this remains a ground-based sport, which is played on grass. The pitch is pill shaped, with two semicircles capping the ends of a rectangle. Superficially, it may appear that the true uniqueness of quidditch is the handicap of being mounted

upon a broomstick, and the possible consequences this has in terms of running and tackling dynamics and injury patterns. However, quidditch is at the forefront of pushing for gender inclusivity in sport with it’s unique mixed-gender rule and full contact nature. Most sports are segregated by sex: with women only competing against women, and men only competing against men. Even the few mixed sex sports dictate a specific number of ‘female’ or ‘male’ players on each team. This can make sport a hostile environment for non-binary athletes (non-binary is defined as “having both masculine and feminine characteristics and/or identifying as being neither male nor female”).7 The IQA (International Quidditch Association) have a “four maximum” gender rule which states that a team can contain a maximum of four players actively playing who identify as the same gender at one time.3 This means that a player of any gender, whether they do or do not identify with a gender at all, can be involved. Quidditch has previously been likened to rugby, due to its full contact nature and lack of body padding.8 Therefore it could be assumed that the two sports will have similar injury patterns. However, the addition of the broom, and the mixed gender aspect of the sport make quidditch unique. The purpose of this study is to therefore examine the types of injuries sustained while playing quidditch in terms of their incidence, anatomical distribution and severity, and gender distribution. This will hopefully determine the safety of the sport under the current rules and provide information for the public, athletes and medical professionals. METHODS A descriptive epidemiological study was conducted to examine injury patterns sustained by quidditch club members registered with the national governing body, Quidditch UK. All athletes who were recorded as having competed in a competitive match in the most recent season were invited to participate in a self-reporting questionnaire. An introductory statement on the questionnaire stated that participation in the questionnaire is completely voluntary and that all information given is confidential. Consent was implied by the participant completing the questionnaire. Data collection took place between March and July of 2016.

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A web-based survey was created on GoogleDrive, a third-party site, which allowed confidential data to be collected. Data collection referred to the previous 12 months and included patient demographics; number of years’ experience; self-reported skill level defined as novice, intermediate or advanced; type of injury sustained; mechanism of injury; player position at time of injury; number of injuries sustained; type of medical professional that was the first responder; treatment required and time of return to quidditch. Incidence was defined as rate of injury per 1,000 hours of quidditch played during the study period. Both practices and matches were included in this figure. Injury was defined as any injury sustained whilst playing quidditch that required “medical attention”, meaning the players medical condition was assessed by a qualified professional, including first aiders, nurses, paramedics and doctors. A superficial injury is defined as an abrasion, superficial hematoma, and superficial laceration. Statistical analysis was performed using SPSS Version 20.0 (IBM, Armonk, New York, USA). A chi-squared test was performed for analysis of categorical data. RESULTS Demographics A total of 348 participants of 684 eligible athletes responded to the questionnaire representing a 50.87% response rate. Of these there were 164 females, 176 males, and five transgender participants. Three participants did not disclose their sex. Overall mean height of athletes was 170.37cm (SD 22.33cm), mean weight was 71.57kg (SD 18.74) and mean BMI was 24.02kg/m2 (SD 6.84). Hours played per week The mean number of hours played per week per player was 4.28 (SD 1.86). The total number of hours played was 77,532 hours in the year studied.

Incidence of Injury There were 315 injuries reported by 180 athletes in total, with an overall incidence of 4.06 injuries per 1,000 hours. Data on player position and type of injury sustained was missing for 14 of these injuries. Players of increasing skill level were observed to report higher injury rates (see Table 1). Ninety-five participants sustained one injury, 52 sustained two injuries, 22 sustained three injuries, five sustained four injuries, and six sustained five injuries overall. There were 141 injuries in females, 163 in males, eight in transgender players and three in athletes who did not disclose their sex. Twenty-seven injuries were sustained in seekers, 151 were sustained in chasers, 77 were sustained in beaters, 44 sustained in keepers and two sustained in snitches (Table 2). Types of injury No differences were seen between males and females in superficial injuries (p=0.103), sprains (p=0.129), fractures (p=0.854) or dislocations (p=0.750) (Table 3). A statistically significantly different rate of concussion was observed with female athletes sustaining more concussion injuries than males (p=0.006). In particular female beaters sustained far more concussions (n=17) compared with their male counterparts (n=2), (p=0.002). The overall rate of concussion was 0.651/1000hrs in males and 1.163/1000hrs in females (0.877/1000 hours overall). Treatment Of those injuries that were not treated in hospital, 70 were managed by a paramedic, 102 were managed by a volunteer first-aider, 25 were managed by a primary care physician and two were managed at a minor injuries centre. Data on treatment was missing for 29 injuries. A total of 17 injuries required hospital admission. Sixty-eight presented to the emergency department

Table 1. Number of injuries per self-perceived skill level.

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Table 2. Frequency of injury location per player position.

Table 3. Frequency of injury between males and females.

and did not require hospital admission. One patient presented to an otolaryngologist and one patient was managed by a nurse (but not in the emergency department). For those patients admitted to hospital and requiring surgical input: one participant was conservatively managed for a tibial fracture; one participant required wrist open reduction internal fixation, one participant underwent open reduction and internal fixation for a tibial fracture; one underwent double meniscus repair and ACL reconstruction; one required single meniscus repair and ACL reconstruction; one required a diagnostic knee arthroscopy, one required an open ACL reconstruction. Return to quidditch The mean time to return to quidditch was 27.37 days (SD 45.48, Range 0-365). Data on recovery time was missing from 55 injuries. Three injuries resulted in those participants not returning to quidditch. DISCUSSION Incidence of injury Incidence of injury was found to be 4.06 per 1,000 hours. Actual practical and game incidence rates could not be specified, but this overall figure appears to be low in comparison with injury rates of other

team sports. For example, men’s amateur rugby league has been found to have injury rates as high as 114 per 1000 hours, amateur Australian football has an injury rate of 27.2 per 1000 hours and professional men’s football has been reported as having an injury rate of 8.0 per 1,000 hours.9,10,11 Types of injury Head and extremity injuries were the most common injuries observed in quidditch. This is a similar injury pattern seen in a study of youth rugby injuries.12 The concussion incidence rate is of particular interest, which was reported as 0.877/1000 hours. In isolation, this does not appear to be an alarming figure when compared to other full contact sports, for example the concussion incidence rate in a study of rugby league injuries was 8/1000 hours.13 A systematic review of rugby league injuries estimated the incidence of concussion during match play to be as high as 8.0 and 17.5 injuries/1000 playing hours, however this study also highlighted large variation in concussion rates due to different methods of sampling and different definitions of injury used.14 Over twenty percent of quidditch injuries (21.5%) reported were described as ‘concussion’. This is relatively high when compared to other full contact sports, for example amateur rugby union where con-

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cussion constituted 4.7% of the injuries reported.15 Even in professional level rugby, concussion only formed 3-10% of injuries.16 Therefore while the absolute risk of concussion compared to other mainstream contact sports is low, concussion seems to be over represented in the sport of quidditch. It was also observed that more females sustained concussion compared with males (42 vs. 26). In particular, female beaters reported far higher numbers of concussion vs. male chasers (17 vs. 2). Observed differences in concussion rates warrant further investigations. In the last 10 years, the understanding of concussion as a brain injury has become accepted in many sports. The need for immediate withdrawal from play of the athlete, assessment with SCAT 3 and graduated return to play has become widely accepted.17 This recognition is as important for amateur sport as it is for professional sport. In the case of quidditch as an amateur sport the minimal time between concussion and return to play should be 12 days. Furthermore, in the case of a second concussion within 12 months’ medical review should be sought. The findings of this study should inform the discussions of the International Quidditch Association around both the information provided to participants and the education necessary to recognise and manage concussion when it occurs. Gender and injury There are mixed findings in the literature regarding injury patterns in players of different genders. For example, it has been reported that female athletes have a higher incidence of ACL injuries than male athletes.18 19 Conversely, the main finding in a Belgian study of football players was that the injury rate was 24% lower in females.20 These findings may suggest that in some sports, there is a difference in incidence of injury between genders and the type of injury may be the differentiating factor between gender rather than the overall incidence. In this study there was no statistically significant overall difference in rates of injury between different genders in superficial injuries (p=0.103), sprains (p=0.129), fractures (p=0.854) or dislocations (p=0.750), which bolsters the quidditch community’s position on a safe gender inclusive sport.

Skill level and injury Players of increasing self-reported skill level were observed to have higher injury rates. This result may be due to confidence of the more advanced players to go in for tackles or collisions during the game where risk of injury is greater. Another explanation is that advanced players may have played a higher proportion of their hours as games, and as such were exposed to a higher risk of injury at these times. Player position and injury Chasers sustained the most injuries out of the injured population. However, information about the non-injured population’s playing positions within the 12 month period is not available. So while it can be shown that the most chasers got injured out of all the players that reported an injury, whether this is a high or low proportion of all the chasers in the UK cannot be determined. Therefore a causal link cannot be made as positions of players who did not sustain an injury within the 12-month period were not recorded and relative risk calculations could not be performed. Snitches and seekers sustained the fewest injuries, perhaps as a result of less game time. In quidditch, the snitch gets released on the 18th minute of the game. This means that the snitch and the seeker only commence involvement from the 18th minute onwards. There are also fewer players in these positions in play at any one time. Considering the fact that the average game lasts approximately 30-40 minutes, this means that these positions receive about half the amount of game time as other positions, for example chasers. Counterbalancing the lack of comparative game time, snitching is anecdotally known to be an aggressive role, which may increase the risk of injury. The athlete spends the duration of their game evading two seekers and can use full contact to do so. Study strengths and limitations This study is the first of its kind to explore risk of injury in quidditch. It is important to quantify injury risk in any new sport, but particularly important in quidditch considering the rapid increase in participation globally. As a pilot study, this stands alone to describe the injuries observed over a 12-month period amongst quidditch players in the

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UK, however, its limitations reduce the strength of any conclusions drawn. The response rate of this survey was 50.9%, and as such may predispose to non-response bias. Fortunately the sample consists of every registered active quidditch player in the UK, and is therefore representative of the population of interest. Non-response bias was minimized by clearly stating that responses were confidential, and not asking identifiable information such as team name. Non-response bias may have been caused if injured athletes were more likely to complete the questionnaire than uninjured teammates, for example if they believed their responses were more useful to the study. However, athletes were encouraged to complete the questionnaire with equal emphasis on injured and non-injured athletes. It is also important to note the possibility of recall bias, as the players were expected to recall the details of injuries from the past twelve months. The whole basis of the study is reliant on self-reported data, so the possibility of inaccurate reporting should be considered. Estimating exposure time for each player is more complex in quidditch than other sports due to match length variance as the game ends when the snitch is caught, not after a set time period. Players were asked to report average hours played per week. The respondents were not asked to specify whether their injuries were sustained during practice or game time, and similarly the respondents were not asked to define their playtime as such. A further limitation is the possibility of misreporting chronic overuse injuries. This could be the case due to the fact that the injury definition used included the need for the player to require medical attention on the pitch. Some chronic overuse injuries may alternatively present to a general practitioner or a physiotherapist, rather than requiring medical attention acutely during play. Furthermore, the study relies of the self-reported information from the players. Understanding of medical terminology will differ between participants and sometimes it is difficult to understand what a participant means by a particular response. For example, one player described a ‘double meniscus repair’, but it is unclear what the player is describing anatomically.

Future research Follow up studies should focus on collecting more information about player exposure to quidditch, in terms of time spent playing games and in practice. Medical literature on injuries in other sports has previously shown considerable difference in injury rates, depending on the context/nature of the participation, for example training vs. games.21 22 It would also be useful to collect more information about players who are not in the injured cohort, for example what position they usually play. In order to form a causal link between position of player and injury rate, this information is vital. At this stage, the impact the broomstick has on injury patterns cannot be determined, and so further research could also focus on mechanism of broomstick related injury. This is important to analyze as it is one of the factors that makes quidditch a unique sport, along with its mixed gender nature. A prospective observational study would be preferable for future research into quidditch injuries to eliminate several forms of bias encountered. However this pilot study gives an overview of a new sport and will guide further research efforts. CONCLUSION Quidditch is an inclusive sport, but, like its fictional relation, it is not without risk of injury. The risk of all injury appears no greater than other established sports, despite the mixed gender nature. However, there is a high incidence of concussion in quidditch which needs to be explored in future research. In the interim, education around the recognition and management of concussion should be made a priority. REFERENCES 1. About. International Quidditch Association website. http://iqaquidditch.org/about.html. Accessed July 10, 2017. 2. Homepage. International Quidditch Association website. http://iqaquidditch.org/. Accessed July 10, 2017. 3. Off to a flying start: Quidditch Premier League launched in UK. The guardian webstie. https:// www.theguardian.com/books/2016/nov/15/ quidditch-premier-league-harry-potter-sport-jkrowling. Accessed July 10, 2017.

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4. What is the British Quidditch Cup? Quidditch UK website. https://quidditchuk.org/BQC. Accessed July 10, 2017. 5. What is the QPL? Quidditch Premier League website. https://quidditchpremierleague.com/what-is-qpl/ Accessed July 10, 2017. 6. US Quidditch rulebook ninth edition. US Quidditch website. https://www.usquidditch.org/files/USQ_ Rulebook_9.pdf. Accessed July 10, 2017. 7. TRANSlation. LGBT Youth Scotland webisite. Page 2. https://www.lgbtyouth.org.uk/files/documents/ youthresources/Translation_-_Gender_Identity_ Explained.pdf. Accessed July 10, 2017. 8. Safety in Quidditch: A Pre-Report. US Quidditch website. https://www.usquidditch.org/ news/2012/10/safety-in-quidditch-a-pre-report Accessed July 10, 2017. 9. Stephenson S, Gissane C, Jennings D. Injury in rugby league: a four year prospective survey. Br_J Sports Med. 1996; 30: 331-334. 10. Gabbe B, Finch C, Wajswelner H, Bennell K. Australian football: injury profile at community level. J Sci Med Sport. 2002; 5(2): 149-160. 11. Ekstrand J, Hagglund M, Walden M. Injury incidence and injury patterns in professional football: The UEFA injury study. Br J Sports Med. 2009; 45(7): 553–558. 12. Archbold HAP, Rankin AT, Webb M, et al. RISUS study: Rugby injury surveillance in Ulster schools. Br J Sports Med. 2017; 51 (7): 600-606. 13. Stephenson S, Gissane C, Jennings D. Injury in rugby league: a four year prospective survey. Br_J Sports Med. 1996; 30: 331-334. 14. Gardner A, Iverson GL, Levi CR, Schofield PW, Kay-Lambkin F, Kohler RM, Stanwell P. A systematic review of concussion in rugby league. Br J Sports Med. 2015; 49 (8): 495-498.

15. Swain MS, Lystad RP, Henschke N, Maher CG, Kamper SJ. Match injuries in amateur Rubgy Union: a prospective cohort study – FICS Biennial Symposium Second Prize Research Award. Chiropr Man Therap. 2016. 24: 17. 16. Kaux J-F, Julia M, Delvaux F, Croisier J-L, Forthomme B, Monnot D, Chupin M, Crielaard J-M, Goff C, Durez P, Ernst P, Guns S, Laly A. Epidemiological review of injuries in Rugby union. Sports. 2015; 3 (1): 21–29. 17. McCrory P, Meeuwisse WH, Aubry M, et al. SCAT3. Br J Sports Med. 2013; 47 (5): 259–262. 18. Agel J, Arendt EA, Bershadsky B. Anterior Cruciate ligament injury in national collegiate athletic association basketball and soccer: A 13-Year review. Am J Sports Med. 2005; 33 (4): 524–530. 19. Myklebust G, Maehlum S, Holm I, Bahr R. A prospective cohort study of anterior cruciate ligament injuries in elite Norwegian team handball. Scand J Med Sci Sports. 1998; 8 (3): 149–153. 20. Mufty S, Bollars P, Vanlommel L, Van Crombrugge K, Corten K, Bellemans J. Injuries in male versus female soccer players : Epidemiology of a nationwide study. Acta Orthop Belg. 2015; 81 (2): 289-295. 21. Dick R, Romani WA, Agel J, Case JG, Marshall SW. Descriptive Epidemiology of Collegiate Men’s Lacrosse Injuries: National Collegiate Athletic Association Injury Surveillance System, 1988–1989 Through 2003–2004. J Athl Train. 2007; 42 (2): 255–261. 22. Dick R, Ferrara MS, Agel J, Marshall SW, Hanley MJ, Reifsteck F. Descriptive Epidemiology of Collegiate Men’s Football Injuries: National Collegiate Athletic Association Injury Surveillance System, 1988–1989 Through 2003–2004. J Athl Train. 2007; 42 (2): 221-233.

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IJSPT

CASE SERIES

FUNCTIONAL OUTCOMES OF HIP ARTHROSCOPY IN AN ACTIVE DUTY MILITARY POPULATION UTILIZING A CRITERION-BASED EARLY WEIGHT BEARING PROGRESSION K. Aaron Shaw, DO1 Jeremy M. Jacobs, MD1 J. Richard Evanson, MD1 Josh Pniewski, DPT1 Michelle L. Dickston, DPT1 Terry Mueller, DO1 John A. Bojescul, MD1

ABSTRACT Introduction: Hip arthroscopy allows surgeons to address intra-articular pathology of the hip while avoiding more invasive open surgical dislocation. However the post-operative rehabilitation protocols have varied greatly in the literature, with many having prolonged periods of limited motion and weight bearing. Purpose: The purpose of this study was to describe a criterion-based early weight bearing protocol following hip arthroscopy and investigate functional outcomes in the subjects who were active duty military. Methods: Active duty personnel undergoing hip arthroscopy for symptomatic femoroacetabular impingement were prospectively assessed in a controlled environment for the ability to incorporate early postoperative weight-bearing with the following criteria: no increased pain complaint with weight bearing and normalized gait pattern. Modified Harris Hip (HHS) and Hip Outcome score (HOS) were performed preoperatively and at six months post-op. Participants were progressed with a standard hip arthroscopy protocol. Hip flexion was limited to not exceed 90 degrees for the first three weeks post-op, with progression back to running beginning at three months. Final discharge was dependent upon the ability to run two miles at military specified pace and do a single leg broad jump within six inches of the contralateral leg without an increase in pain. Results: Eleven participants met inclusion criteria over the study period. Crutch use was discontinued at an average of five days following surgery based on established weight bearing criteria. Only one participant required continued crutch use at 15 days. Participants’ functional outcome was improved postoperatively, as demonstrated by significant increases in HOS and HHS. At the six month follow up, eight of 11 participants were able to take and complete a full Army Physical Fitness Test. Conclusions: Following completion of the early weight bearing rehabilitation protocol, 81% of participants were able to progress to full weight bearing by four days post-operative, with normalized pain-free gait patterns. Active duty personnel utilizing an early weight bearing protocol following hip arthroscopy demonstrated significant functional improvement at six months. Level of Evidence: Level 4, Case-series Key words: Active-duty military, functional outcomes, hip arthroscopy, postoperative weight bearing

1

Dwight David Eisenhower Army Medical Center, Ft Gordon, GA, USA

No funding was received for this study. Each author certifies that he or she has no commercial associations that might pose a conflict of interest in connection with the submitted article. The opinions or assertions contained herein are the private views of the authors and are not to be construed as official or reflecting the views of the Department of Defense or US Government. The authors are employees of the US government. This work was prepared as part of their official duties and, as such there is no copyright to be transferred.

CORRESPONDING AUTHOR K. Aaron Shaw, DO Department of Orthopaedic Surgery 300 East Hospital Road Fort Gordon, GA 30905 P: (706) 787-6158 Fax: (706) 787-2901 E-mail: kenneth.a.shaw34.mil@mail.mil

The International Journal of Sports Physical Therapy | Volume 12, Number 5 | October 2017 | Page 840 DOI: 10.16603/ijspt20170840

INTRODUCTION Hip arthroscopy has become a growing treatment option for femoracetabular impingement (FAI). Numerous authors have demonstrated that hip arthroscopy is a successful treatment modality with high rates of return to sport, as well as significant improvements in clinical and functional outcomes.1-6 Additionally, it has been found to be a safe procedure with a low rate of major and minor complications, estimated at 0.58% and 7.5% respectively.1 Rehabilitation following hip arthroscopy is integral to the clinical outcome.7 However, there is a vast disparity in the post-operative rehabilitation protocols reported through the literature,8 including weight bearing restriction,8-12 brace use,13-15 and utilization of continuous passive motion machines5,13,14 with variations in these components according to specific procedures performed.8 Some of these restrictions are put in place to facilitate healing following surgery but others are related to early catastrophic complications, including femoral neck fractures and hip dislocations and instability,16,17 but all lack the support of high quality evidence.8 The purpose of this case series was to describe a criterion-based early weight bearing protocol following hip arthroscopy and investigate functional outcomes in the subjects who were active duty military. The authors hypothesized that weight bearing restrictions after hip arthroscopy can be counterproductive and may lead to post-operative sequelae including adhesion formation, hip flexor contractures, increased capsular tension with internal and external rotation, and altered gait patterns. METHODS Patients undergoing hip arthroscopy between May 2011 and June of 2012 for symptomatic FAI were prospectively evaluated. Inclusion criterion included active-duty personnel undergoing arthroscopic surgery for FAI treated with femoral neck osteochondroplasty, acetabuloplasty, labral repair or debridement, and/or fractional psoas lengthening who received postoperative therapy by a single physical therapist at the treating facility. Diagnosis of FAI was determined by one of two sports medicine fellowship trained orthopaedic surgeons upon assimilation of clinical exam and radiographic studies. Patients

were excluded from participation if they were not active military personnel or received therapy at another facility. Functional outcome measures were assessed using the modified Harris Hip score (HHS) and the Hip Outcome Score (HOS) preoperatively and re-administered six months following surgery. All subjects were treated with a criterion-based early weight bearing progression post-operatively in controlled environments. Full weight bearing as tolerated was permitted immediately following surgery using bilateral crutch assistance with progression to full weight bearing facilitated according to the criteria presented in Table 1. Subjects self-restricted weight bearing with crutch assistance and were progressed to full, unassisted weight bearing through formal gait instruction, beginning with a step-to gait pattern, followed by step-through gait pattern with crutch assistance and progressing to unassisted gait as tolerated. A normalized gait pattern was identified as near symmetrical hip extension at toe-off when comparing the side of the surgical intervention to the non-involved side during visual gait analysis. Subjects were progressed with a standardized hip arthroscopy protocol, consisting of a four-phases progression. The protocol was standardized for all arthroscopic hip procedures, with no deviations determined by the type of surgical intervention (Appendix 1 and 2). Progression through the phases was dictated by to patient performance on weight bearing progression and time following surgery. Phase I covers, on average, the first three weeks following surgery. During this time, subjects are allowed immediate weight-bearing as tolerated, discontinuing crutch use immediately if the patient achieves progression criteria presented in Table 1. Subjects are supervised through stretching exercises and non-resisted straight-leg raises and heel slides. They also begin stationary bike using slow revolution to emphasize hip motion. Hip flexion is limited to not exceed 90 degrees for the first three weeks post-op. Once subjects have completed the weight bearing progression and have full passive motion with a non-antalgic gait, they are transitioned to Phase II for weeks 3-6 during which time strengthening exercises are added with proprioceptive exercises and treadmill walking. Running is restricted for the first

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Table 1. Progressive weight bearing philosophy for rehabilitation following hip arthroscopy. Questions are designed to be answered by the treating therapist.

12 weeks. Subjects then progress to Phase III with more intensive proprioceptive and plyometric exercises with continued strengthening exercises aimed at restoration of symmetric muscular strength. Phase IV begins at three months post operative, at which time a supervised walk-to-run program is implemented and subjects are allowed to begin situp and push-up training (two of the three criteria assessed as part of the Army Physical Fitness Test (APFT) with the third component consisting of a two mile run). At the completion of the four phase protocol, subjects are released from activity restrictions (US Army physical profile) and allowed to complete an APFT, a biannual requirement for all military personnel. Statistical Methods Demographic and functional outcome measures were recorded for all patients. Activity restrictions were identified by identifying the presence of a profile by cross-referencing the US Army Physical Disability Agency database to identify activity restrictions as related to training and completion of an APFT. The ability to pass an APFT was also recorded. Functional outcome scores, HHS and HOS, were compared before surgery and at final follow up with paired Students t-test with calculation of 95% confidence intervals. Statistical significance was predetermined as p=0.05. RESULTS Sixty subjects were identified for participation during the study period. Of these, 19 subjects were excluded due to non-active military status, with an additional 30 subjects excluded for receiving there

therapy at another institution leaving 11 service members who met enrollment criteria. All 11 subjects underwent hip arthroscopy to address various subtypes of FAI and completed rehabilitation using the accelerated weight bearing rehabilitation protocol. Complete follow-up examinations were performed in 11/11 (100%) active duty soldiers and all subjects completed a full rehabilitation course. Average follow-up was six months and no subjects were lost to follow-up. In addition to diagnostic arthroscopy, post-operative procedures included labral debridement (n=3), labral repair (n=7), femoral neck osteochondroplasty (n=7), and acetabuloplasty for pincer lesion (n=6). Demographic data, pre-operative, and post-operative outcomes scores are listed in Table 2 and statistical analysis is summarized in Table 3. Crutch use was discontinued at an average of five days following surgery based on established weight bearing criteria. Only one subjects required continued crutch use at 15 days. Mean preoperative HHS and HOS scores were 59.8 and 61.1 respectively. These measures improved to 94.1 (HHS) and 95.23 (HOS) at the six month visit. The mean improvement in HHS score was 34.3 and the mean improvement in HOS score was 34.2. Both outcomes had a an effect size > 3.3, indicating a high overall impact of the surgery. There was a statistically significant difference (p < 0.01) comparing pre-operative and post-operative outcome scores for both the HHS and HOS questionnaires. In addition, the function in sport subscale of the HOS demonstrated similar results improving 37.1 points from 56.7 pre-operatively to 93.7 at the six month visit. This change was also found to be statistically significantly different (p < 0.01).

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Table 2. Demographic, crutch use, and outcomes scores for patients undergoing hip arthroscopy.

Postoperatively, all subjects were given activity restrictions, referred to as a physical profile in the military, limiting activity and military participation. At six months post-operatively, all subject’s profiles were reviewed evaluating ongoing limitations. Three of 11 subjects (27%) had continued restriction with regard to performing the two-mile run event of the APFT. All other subjects (8/11) passed this event without restrictions. All subjects (11/11) completed the sit up and pushup events. All eleven service members were deemed deployable at the conclusion of the study period. There were no reported complications including: infection, femoral neck fracture, dislocations, heterotopic ossification, avascular necrosis of the femoral head, or loss of fixation concerning labral repairs. No neurovascular injuries occurred during hip arthroscopy in this population.

DISCUSSION Many existing protocols for rehabilitation after hip arthroscopy have comparable initial goals which include initial stretching exercises, ROM, and strength restrictions.8,11-14,18 Weight bearing status has considerable variation between surgeon and procedure, with some protocols restricting weight bearing during the first four to six weeks while others allow immediate weight-bearing for specific procedures.8,13,14,18 In this study, weight bearing is initiated in a controlled environments without crutches as early as the second day following surgery, regardless of the surgical procedure performed. Progression to full weight bearing was dictated by subject ability to pass the criterion described, as well as their tolerance and motivation. Requirements for transition to unprotected weight bearing included toleration to pain and near normal gait pattern. Subjects who

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Table 3. Comparison of functional outcome score before and after surgery.

participated in this study had significantly improved HHS scores and HOS at six months, with minimal restriction on military duty. The outcomes of this study are comparable to previously reported studies with significant functional improvement as well as high return to sport/activity.4-7,13,14,18-20 This studies results suggest that accelerated weight bearing and early ROM can assist in attaining positive outcomes in terms of early improvements in rehabilitation while minimizing potential adverse effects, a concept that is supported in the literature.18 Likewise, there were no observed failures related to early weight bearing to include catastrophic failures such as femoral neck fracture or hip instability.

may have introduced bias. The US Army physical profile was also used to assess outcomes and many of the limitations placed upon a soldier are subjective according to the individual provider’s assessment of function and physical abilities. Neither the Army physical profile or the APFT have been validated as outcomes measures but have been used in numerous previous studies as an adjunct for functional outcomes.2, 21-23 Deployment standards are also variable according to job description within the military. Additionally, no subject included in this study underwent a capsular closure. As such, the extrapolation of these results to subjects undergoing a capsular closure is limited.

Limitations inherent to this study include the lack of a control group. Likewise, the sample size is small (inherent to a case series), limiting the ability to perform detailed subgroup analysis and the subject population does not reflect the general population, limiting its external validity. Although one therapist administered treatment and collected post-operative data, he was not blinded to study directives which

CONCLUSIONS In conclusion, the results of this case series support the implementation of early weight-bearing using a criterion-based protocol in a controlled setting for patients undergoing hip arthroscopy for symptomatic FAI. Future studies are needed to assess the long-term outcomes in active-duty patients treated with this protocol.

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REFERENCES 1. Harris JD, McCormick FM, Abrams GD, et al. Complications and reoperations during and after hip arthroscopy: a systematic review of 92 studies and more than 6,000 patients. Arthroscopy. 2013;29:589595. 2. Dutton JR, Kusenzov NA, Lanzi JT, Garcia EJ, Pallis MP. The Success of Hip Arthroscopy in an Active Duty Population. Arthroscopy. 2016;32:2251-2258. 3. Gillespie JA, Patil SR, Meek RD. Clinical outcome scores for arthroscopic femoral osteochondroplasty in femoroacetabular impingement: a quantitative systematic review. Scot Med J. 2015;60:13-22. 4. McCarthy J, Barsoum W, Puri L, Lee JA, Murphy S, Cooke P. The role of hip arthroscopy in the elite athlete. Clinical orthopaedics and related research. 2003:71-74. 5. McDonald JE, Herzog MM, Philippon MJ. Return to play after hip arthroscopy with microfracture in elite athletes. Arthroscopy. 2013;29:330-335. 6. Redmond JM, El Bitar YF, Gupta A, Stake CE, Vemula SP, Domb BG. Arthroscopic acetabuloplasty and labral refixation without labral detachment. Am J Sports Med. 2015;43:105-112. 7. Bedi A, Chen N, Robertson W, Kelly BT. The management of labral tears and femoroacetabular impingement of the hip in the young, active patient. Arthroscopy. 2008;24:1135-1145. 8. Grzybowski JS, Malloy P, Stegemann C, Bush-Joseph C, Harris JD, Nho SJ. Rehabilitation Following Hip Arthroscopy - A Systematic Review. Frontiers in surgery. 2015;2:21. 9. Edelstein J, Ranawat A, Enseki KR, Yun RJ, Draovitch P. Post-operative guidelines following hip arthroscopy. Curr Rev Musculoskeltal Med. 2012;5:1523. 10. Domb BG, Sgroi TA, VanDevender JC. Physical Therapy Protocol After Hip Arthroscopy: Clinical Guidelines Supported by 2-Year Outcomes. Sports Health. 2016;8:347-354. 11. Wahoff M, Dischiavi S, Hodge J, Pharez JD. Rehabilitation after labral repair and femoroacetabular decompression: criteria-based progression through the return to sport phase. Inter J Sports Phys Ther. 2014;9:813-826. 12. Wahoff M, Ryan M. Rehabilitation after hip femoroacetabular impingement arthroscopy. Clin Sports Med. 2011;30:463-482.

13. Nho SJ, Magennis EM, Singh CK, Kelly BT. Outcomes after the arthroscopic treatment of femoroacetabular impingement in a mixed group of high-level athletes. Am J Sports Med. 2011;39 Suppl:14s-19s. 14. Philippon MJ, Briggs KK, Yen YM, Kuppersmith DA. Outcomes following hip arthroscopy for femoroacetabular impingement with associated chondrolabral dysfunction: minimum two-year follow-up. J Bone Joint Surg Br. 2009;91:16-23. 15. Marchie A, Panuncialman I, McCarthy JC. Efficacy of hip arthroscopy in the management of synovial chondromatosis. Am J Sports Med. 2011;39 Suppl:126s-131s. 16. Matsuda DK. Acute iatrogenic dislocation following hip impingement arthroscopic surgery. Arthroscopy. 2009;25:400-404. 17. Ayeni OR, Bedi A, Lorich DG, Kelly BT. Femoral neck fracture after arthroscopic management of femoroacetabular impingement: a case report. J Bone Joint Surg Am. 2011;93:e47. 18. Byrd JW, Jones KS. Arthroscopic management of femoroacetabular impingement: minimum 2-year follow-up. Arthroscopy. 2011;27:1379-1388. 19. Domb BG, Dunne KF, Martin TJ, et al. Patient reported outcomes for patients who returned to sport compared with those who did not after hip arthroscopy: minimum 2-year follow-up. J Hip Preserv Surg. 2016;3:124-131. 20. Larson CM, Giveans MR, Stone RM. Arthroscopic debridement versus refixation of the acetabular labrum associated with femoroacetabular impingement: mean 3.5-year follow-up. Am J Sports Med. 2012;40:1015-1021. 21. Nute DW, Kusnezov N, Dunn JC, Waterman BR. Return to Function, Complication, and Reoperation Rates Following Primary Pectoralis Major Tendon Repair in Military Service Members. J Bone Joint Surg Am. 2017;99:25-32. 22. Scully WF, Parada SA, Arrington ED. Allograft osteochondral transplantation in the knee in the active duty population. Mil Med. 2011;176:1196-1201. 23. Eisenstein ED, Lanzi JT, Waterman BR, Bader JM, Pallis MP. Medialized Clavicular Bone Tunnel Position Predicts Failure After Anatomic Coracoclavicular Ligament Reconstruction in Young, Active Male Patients. Am J Sports Med. 2016;44:26822689.

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Appendix 1. Overview of the Four Phase post-surgical hip arthroscopy rehabilitation protocol.

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Appendix 1. (continued) Overview of the Four Phase post-surgical hip arthroscopy rehabilitation protocol.

Appendix 2. Plyometric and proprioceptive exercises performed during the various phases of the postsurgical hip arthroscopy protocol.

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IJSPT

CASE REPORT

EXERCISE, MANUAL THERAPY AND POSTURAL RE-EDUCATION FOR UNCONTROLLED EAR TWITCHING AND RELATED IMPAIRMENTS AFTER WHIPLASH INJURY: A CASE REPORT Kelsey Flanders, PT, DPT, CLT1 Heather Feldner, PT, DPT, PhD, PCS2

ABSTRACT Background and Purpose: Whiplash Associated Disorders and the interventions used to remediate them are well documented in physical therapy literature. However, specific interventions for spasms of the neck musculature that also involve constant ear twitching have yet to be addressed. The purpose of this case report is twofold. First, to describe comprehensive physical therapy management and outcomes for a subject with uncontrolled ear twitching and related musculoskeletal impairments, and second, to discuss the physical therapist’s approach to evidence-based care when faced with a paucity of literature addressing physical therapy interventions for subjects with uncontrolled ear twitching. Case Description: The subject was a 14-year-old female who sustained a right anterolateral whiplash injury when struck in the head by a volleyball seven months prior to physical therapy. Beginning five months after that injury, she experienced uncontrolled and constant superior/inferior movement of her right ear (hereafter described in this report as a twitch) in addition to facial and cervical pain from her initial injury. She was unable to participate in high school athletics due to her pain. A multimodal treatment approach including exercise, manual therapy, and postural reeducation was utilized during the subject’s episode of care. Outcomes: After eight treatment sessions, the subjects’s cervical range of motion and upper extremity strength improved. The reported frequency of ear twitching decreased, as did reports of neck and shoulder pain. In addition, her Neck Disability Index improved from a score of 22, indicating moderate disability, to 9, indicating mild disability and she was able to return to sport activity. Discussion: With limited research to direct intervention, clinical reasoning was utilized to formulate an effective therapeutic intervention. A combination of manual therapy, exercise, and postural reeducation intervention was effective for this subject and could assist in guiding interventions for similarly unique clinical presentations in the future. Further research is needed to examine the etiology of ear twitching caused by muscle spasm and to develop additional evidence-based interventions for Whiplash Associated Disorders. Level of Evidence: Level 4 Key words: Ear twitching, manual therapy, postural reeducation, sternocleidomastoid muscle spasm, whiplash associated disorders

1 2

Saint Alexius Medical Center, Hoffman Estates, IL, USA Department of Mechanical Engineering, University of Washington, Seattle, WA, USA

CORRESPONDING AUTHOR Kelsey Flanders Saint Alexius Medical Center 1555 Barrington Rd, Hoffman Estates, IL, 60169 Phone: (847) 309-5941 E-mail: kflan1109@gmail.com

The International Journal of Sports Physical Therapy | Volume 12, Number 5 | October 2017 | Page 848 DOI: 10.16603/ijspt20170848

BACKGROUND AND PURPOSE Whiplash Associated Disorders (WAD) are extremely common in North America, and have a significant impact on individuals in terms of physical and psychosocial dysfunction, including long-term physical impairment, pain, and mental health conditions such as anxiety, depression, and post-traumatic stress disorder.1 Over half of patients with WAD report pain and physical dysfunction 12 months or longer following their initial injury.1 Further, WAD takes a large economic toll, resulting in over 200 billion dollars in health care expenditures yearly.2 While neck pain is the hallmark symptom of WAD, other symptoms have been reported in the literature, including headache, vestibular and visual changes, paresthesia, upper extremity pain, widespread stiffness and non-specific muscle spasm.1,3,4 Whiplash injuries are often discussed in the context of motor vehicle collisions, but can occur as a result of any impact characterized by a rapid acceleration followed by a rapid deceleration of the neck and head.5 Research into non-conventional whiplash impacts note that different directions of impact cause unique muscle responses and ultimately, unique cervical dysfunctions.6 Whiplash-associated cervical muscle spasms can be identified by the direction of impact. In rear-end impacts, the main impact is on the sternocleidomastoid (SCM) muscle. In frontal impacts, the upper trapezius muscle is commonly involved, and in lateral impacts, the splenius capitis is most affected.7 Kumar et. al.6 found that during injuries involving anterolateral impacts, the SCM, splenius capitis and upper trapezius electromyography (EMG) peak amplitudes increase steadily with increased magnitude of impact. In addition, head and neck acceleration and the resultant muscle response significantly increases when a whiplash impact is unanticipated.6 Physical therapy management for chronic WAD (longer than 12 weeks post-injury) may include exercise programs, manual joint manipulation, and biofeedback training to relieve pain and improve functional ability.5 In light of these findings for whiplash impairments, manual therapy and exercise were hypothesized to produce similar outcomes in a subject who experienced an unanticipated, anterolaterally directed, whiplash injury with resultant long-term

pain and muscle spasms in her neck musculature. These spasms were also uniquely associated with an uncontrolled, continuous, superior-inferior translation of the right ear, referred to in this case report as ‘ear twitching’. At the time of the subject’s initial visit, several authors had addressed the effects of whiplash injuries on neck impairments.1,3,4,8 However, none of the literature discussed the relationship between whiplash injury and ear twitching, nor physical therapy intervention for ear or SCM spasms specifically. Thus, this case report helps to fill a current gap by exploring the effectiveness of physical therapy intervention for ear twitching and associated neck pain and spasms. The purpose of this case report is twofold. First, to describe comprehensive physical therapy management and outcomes for a subject with uncontrolled ear twitching and related musculoskeletal impairments, and second, to discuss the physical therapist’s approach to evidencebased care when faced with a paucity of literature addressing physical therapy interventions for subjects with uncontrolled ear twitching. CASE DESCRIPTION: SUBJECT HISTORY AND SYSTEMS REVIEW A 14-year-old female, in her usual state of excellent health, was hit with a volleyball on the right anterolateral aspect of her head seven months prior to the initial physical therapy visit. Initial symptoms included right facial, bilateral cervical, and bilateral upper back pain. Five months after the initial injury, and two months prior to the initial therapy visit, the subject began her high-school softball season. During softball, the subject began experiencing frequent headaches and constant right “ear twitching”, symptoms which worsened over the subsequent two months leading up to the physical therapy evaluation. The subject’s chief complaints at time of initial evaluation included impaired ability to perform activities of daily living such as reading, texting and carrying a laundry basket. Of greatest importance to the subject, was her inability to participate with her peers in competitive sports due to the pain. The subject had no significant past medical history or comorbidities and was a student-athlete at a local high school. She was receiving no other intervention for her impairments at time of evaluation. The subject’s desired goals were to eliminate ear twitching

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and return to prior participation in high school athletics. CLINICAL IMPRESSION #1 It was evident from the subject’s description that the primary problem was chronic neck and shoulder pain with subacute ear twitching that limited the subject’s ability to participate in high school sports and other daily activities. It was hypothesized that the neck and shoulder pain were due to a combination of poor posture and long-term sequelae from a whiplash-type injury that had occurred seven months prior to the physical therapy evaluation. The most unique portion of the subject’s presentation was the presence of an uncontrolled ear twitch. Initially, it was unclear whether the ear twitching was due to a neuromuscular injury, musculoskeletal injury or combination of the two. A systems review revealed that all vital signs were normal. Additional examination was warranted to determine the precise cause of the ear twitching. Prior brain imaging, taken at the time of injury, was to be reviewed by the referring physician to rule out neurologic injury. A detailed neurological screen was also planned for the physical therapy examination to rule out any possible central nervous system causes. Additionally, a thorough strength, range of motion and segmental mobility evaluation for both the cervical spine and upper extremity was planned. Finally, the Neck Disability Index (NDI) was utilized to provide an objective measure of subject reported functional limitations. The subject’s unusual symptoms and clinical presentation provided a unique opportunity to explore interventions for symptoms without a concrete diagnosis and therefore made her a good candidate for a case report. The authors’ institutional review board granted ethical approval for this case report. The subject’s mother provided informed consent and permission for both creation of a case report and submission for publication, and the subject provided verbal assent to participate in the case report. EXAMINATION Initial medical evaluation by the subject’s primary physician showed normal brain computerized tomography (CT) and magnetic resonance imaging (MRI) scans. The subject was then referred to

physical therapy with a diagnosis of “cervicalgia”, the origin of which was determined to be musculoskeletal in nature. Upon initial observation, the subject’s right ear was repetitively moving superiorly and inferiorly at a rapid rate. Upon closer visual inspection, a spasm of the right proximal SCM muscle was witnessed in conjunction with the right ear movement. In sitting, the subject assumed a forward head posture with protracted scapulae. Upon palpation, bilateral scalene, SCM, and upper trapezius, and right-sided temporalis muscles were tender to palpation with trigger points present throughout each muscle. Palpation of the right side elicited more discomfort than the left. Segmental mobility testing of the cervical and upper thoracic spine revealed hypomobility and pain reproduction, especially with right unilateral posterior to anterior (PA) mobilization at C2 and central PA mobilization at C6-T1. The subject was screened for central nervous system dysfunction using myotome,9,10 dermatome (light touch and sharp/dull),11 and reflex testing in order to rule out neurologic contributions to her symptoms.12 No resting nystagmus, visual field cuts, or light sensitivity was observed. Based on these results, no other specific neurologic tests were performed. The Numeric Pain Rating Scale13,14 was used to assess her self-reported pain. This scale was used because it has been documented in the literature as providing fair to moderate reliability in patients with mechanical neck pain as well as adequate validity for the same population.15 The subject reported her pain at a 7/10 at worst and 5/10 at the time of the initial visit. Manual Muscle Testing (MMT) was performed in standard positions as described by Reese16 on major upper extremity muscle groups in order to assess the relationship between strength impairments and clinical presentation. Grading was assigned as described by Kendall et al.17 Manual muscle testing has been found to have good reliability and validity for neuromusculoskeletal dysfunctions.18 Reese has also summarized the literature of MMT reliability and found “good intra-rater reliability for MMT”.16 However, grades of 4/5 and higher have been found to lack sensitivity and precision which

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causes a ceiling effect.19 Because of this, a hand held dynamometer was utilized to measure grip strength in order to provide another measure of the subject’s strength for comparison. Measurements took place in the standard position,20 as described by Horowitz et al. For healthy adults, dynamometric grip strength measurements were found to have excellent intrarater and inter-rater reliability,21 as well as excellent criterion validity.21 The subject’s grip strength results supplemented the MMT results in order to assess strength impairments and their association with the subject’s functional limitations. The results of the MMT and dynamometry measurements are listed in Table 1. The subject had normal upper extremity range of motion (ROM) in all joints as assessed in standard positions as described by Norkin & White.22 Her cervical ROM was impaired, limited primarily by mus-

cular tightness. Goniometry has been found to be a valid test to measure range of motion,23 as well as possessing high intra-rater reliability for both shoulder24 and neck25 measurements. The results of the cervical ROM measurements are listed in Table 2. In addition, the NDI26 was utilized to assess the subject’s limitations in functional activities. The NDI is a self-report questionnaire that determines to what extent subjects’ neck pain affects their daily life. It has been found to have adequate test-retest reliability for mechanical neck pain26 and excellent construct validity for whiplash-associated disorders.27 The questionnaire has 10 questions, which are rated using a Likert scale of one to five, one being minimal impact on daily activity and five being significant impact on daily activity. A raw score of 5-14 indicates mild disability, 15-24 indicates moderate disability, 25-34 indicates severe disability, and above

Table 1. Manual Muscle Testing and Dynamometry.

Table 2. Cervical Range of Motion.

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34 indicates complete disability. The subject’s raw score of 22 indicated a moderate disability in her daily life due to neck pain. CLINICAL IMPRESSION #2 Following the examination, the data obtained confirmed the initial impression that the subject’s dysfunction was musculoskeletal in nature. Therefore, it was determined that the appropriate plan of action was to initiate physical therapy intervention to address her primary impairments of decreased range of motion, decreased postural awareness, decreased strength and pain. Since no evidence was available at the time to direct treatment for the ear twitch, interventions were directed toward the specific impairments identified during the examination in order to improve her ability to perform functional tasks and return to prior sport activity. This subject continued to be a prime candidate for a case report due to the musculoskeletal nature of her impairments and the limited research available to guide specific intervention for her unique pathological presentation. The subject was scheduled to receive physical therapy intervention twice per week for four weeks, at which point a reassessment would be performed. INTERVENTION The physical therapy intervention plan for this subject was developed by the primary physical therapist utilizing an evidence-based approach. A literature review was conducted using both medical and allied health databases including PubMed, CINAHL, Scopus, and the University of Illinois Chicago library’s literature search engine. Key words used in the search included: “ear twitching”, “ear wiggling”, “ear spasm”, “neck muscle spasm”, “temporalis spasm”, “rehabilitation”, and “physical therapy”. The literature found during that search was minimal and largely irrelevant. The search was then broadened to include: “whiplash” “anterolateral impacts” “chronic neck pain” and “sternocleidomastoid spasm”. While these results did not lead to significantly valuable descriptions of physical therapy interventions for this unique case, they enabled the physical therapist to research similar mechanisms of injury to understand the physiologic repercussions of an anterolateral whiplash injury and develop interventions

to address these impairments. Thus, the physical therapist blended the available literature, input from other experienced physical therapists, clinical practice guidelines for neck pain,28 and the therapist’s own clinical reasoning to develop the specific interventions utilized to address the subject’s impairments and functional limitations. Rehabilitation goals were focused on strengthening postural muscles and mobilizing cervical joints and musculature that were limiting movement and causing pain. Therapeutic exercise is widely used as part of a comprehensive treatment approach to physical therapy management of chronic neck pain. According Pangarkar et. al.,29, p. 510 “Postural evaluation, support and therapeutic exercises are considered to be a foundation of treatment.” Postural habits are believed to contribute to the development of cervical muscle imbalances and subsequent neck pain. Postural awareness and exercises based on stretching, strengthening and range of motion are proposed to help address these deficits. One Cochrane review by Kay et. al.30 found moderate evidence supporting focused stretching and strengthening at the cervical, shoulder and thoracic regions to improve chronic mechanical neck pain. In addition, retraining the deep cervical flexor musculature through strengthendurance and cranio-cervical flexion exercises has been shown to decrease neck pain symptoms for subjects suffering from chronic neck pain and may improve the capacity of the cervical spine to sustain an upright posture.31 In addition to therapeutic exercise, research has shown that a multimodal strategy of therapeutic intervention that utilizes exercise and mobilization/manipulation techniques may result in more significant improvements in pain and function, demonstrating a 28% to 70% treatment advantage over a control subject utilizing exercise alone.32 This information led to the development of a multimodal treatment plan, which included both manual therapy and exercise. A combination of therapeutic exercise, manual therapy, and a home exercise program (HEP) were designed to address the subject’s impairments. Table 3 describes the specific therapeutic interventions performed each session. These exercises were

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Table 3. Intervention Details.

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Table 3. Intervention Details (continued).

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progressed throughout the duration of treatment to include more complex, challenging and sport-specific exercises. Exercises were progressed when the subject was able to perform exercises without cueing for proper form and reported no fatigue with the exercise. Progression occurred by increasing intensity and complexity of exercises, such as advancing from a red to a green resistance band, and incorporating compliant surfaces such as a BOSU® and therapy ball to encourage shoulder and scapular stabilization in addition to strengthening. At the time of intervention, the subject was not receiving any other form of outside treatment for her impairments. OUTCOME After eight physical therapy sessions, the subject met all goals and reported significant improvement in neck pain and ear twitching. Resting neck pain improved from 5/10 at initial evaluation to 2/10 at discharge. She was also able to return to play for her competitive softball team. While the subject’s primary complaint of ear twitching was not completely resolved by discharge, the twitch occurred approximately six times per day as compared to the constant movement experienced at initial visit. The subject reported that in addition to decreased frequency, that she was “somewhat able to control” the ear movement now through active postural repositioning. The subject’s second major complaint of shoulder and neck pain at rest was completely resolved after eight sessions. Her only report of pain was after a lengthy double-header softball game prior to discharge. Her NDI score improved from a score of 22 indicating moderate disability at initial examination to a score of 9 indicating mild disability upon discharge. As the MCID for the Neck Disability Index is 7.5 points for mechanical neck pain,26 this change demonstrates clinically significant results. Specific functional improvements included an improved ability to text, read, and carry laundry without discomfort or onset of ear twitching movement. The strength and range of motion gains made by the subject are shown in Table 1 and Table 2 above. These gains may have contributed to her decreased pain and increased ability to perform functional activities. By her last session, the subject was able to self-correct her posture without cueing. While the

subject still experienced some pain and ear twitching, insurance limitations hindered the continuation of physical therapy intervention. At discharge, the subject planned to maintain compliance with her home exercise program to continue to make therapeutic gains and ultimately felt enough improvement in her symptoms to attend volleyball camp three months after discharge. DISCUSSION This case report presents the course of physical therapy intervention aimed at restoring functional mobility and decreasing the presence of ear twitching in a 14-year-old high school athlete. At the end of eight treatment sessions, the subject achieved all stated therapy goals and returned to competitive sport participation. Researchers have discussed the effects of unconventional whiplash injuries and the subsequently recommended physical therapy interventions, but the literature has failed thus far to report the onset of ear twitching after chronic WAD. In turn, research directing the physical therapy intervention of such a presentation is equally limited. This case highlights the challenge of developing an evidence-based treatment plan for a clinical presentation that is not documented in the literature, as well as provides promising outcomes for clinicians to consider when planning interventions for similar cases. Based on information from whiplash literature noting SCM muscle involvement in anterolateral impact whiplash injuries, as well as the subject’s clinical presentation of right SCM spasm and temporalis tenderness, it was hypothesized that the subject’s constant ear twitching was a result of a SCM spasm, which pulled the ear inferiorly on a resisting temporalis muscle. While a physical therapy diagnosis was not explicitly identified at the time of evaluation, the therapist recognized the unique mechanism of injury and relationship between the SCM muscle spasm and the ear twitch, which then led to the development of a plan of care. Although a formal diagnosis was not made, this working diagnosis guided the interventions, utilizing treatment strategies that were consistent with the available associated research to address the impairments of this unique pathological presentation.

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This case report has several limitations that restrict its ability to be applied to a larger population. The first is the lack of a concrete diagnosis to guide intervention, which has been addressed above. Second, the time frame available for this intervention was limited. Due to insurance limitations, only eight visits were allocated to treat chronic neck pain and subacute ear twitching. While progress was seen in eight visits, a longer duration of treatment may have provided greater clarity as to whether the intervention was successful long term or whether the subject’s progress would have plateaued with the current intervention. Third, long term results are unknown. Attempts to reach the subject following the episode of care were unsuccessful, however, as of this case report submission, thirty-three months following intervention, the subject did not return to the clinic to seek any additional care for associated symptoms. It is unknown whether the ear twitching ceased entirely or returned after the subject resumed sport competition. Finally, it is unclear whether one intervention provided more effect than another since a multimodal approach was utilized. Despite these limitations, while it is impossible in a single case to demonstrate a direct relationship between the interventions provided and the subject’s outcome, a positive outcome has been identified in this report. In this case report, the use of exercise, manual therapy, and postural reeducation resulted in the reduction of pain and frequency of ear twitching, as well as a restoration of functional mobility. Research discussing therapeutic intervention for whiplash-associated dysfunction highlights emerging evidence that a combination of therapeutic exercise and manual therapy are beneficial in subjects who experienced chronic mechanical neck pain as a result of whiplash injury.5,29,31,32 Because a lack of a formal diagnosis makes directing an intervention especially challenging, future research should focus on identifying a concrete diagnosis for constant uncontrolled ear twitching secondary to cervical muscle spasms in order to guide physical therapy intervention specifically for this clinical presentation. CONCLUSION This case report appears to be the first to describe a detailed course of rehabilitation for a subject with

a continuous ear twitch and neck pain after an anterolateral whiplash injury. This case report also details treatment planning for a patient whose clinical presentation cannot be found in the literature. Over eight treatment sessions, the subject made significant improvements in cervical range of motion, neck pain, and ear twitch presence. After treatment, she was able to return to all prior activities including competitive softball and volleyball play. REFERENCES 1. Sterling M. Physiotherapy management of whiplashassociated disorders (WAD). J Physiother. 2014;60(1):5-12. 2. Blincoe L, Seay A, Zaloshnja E, et al. The economic impact of motor vehicle crashes (No. HS-809 446,). Washington, DC, National Highway Traffic Safety Administration. 2002. 3. Heneghan N, Smith R, Rushton A. Thoracic dysfunction in whiplash-associated disorders: A systematic review and meta-analysis protocol. Syst Rev. 2016;5(26). 4. Woodhouse A, Vasseljen O. Altered motor control patterns in whiplash and chronic neck pain. BMC Musculoskelet Disord 2008;9(1):1. 5. Teasell RW, McClure JA, Walton D et. al. A research synthesis of therapeutic interventions for whiplashassociated disorder (WAD): Part 4 - noninvasive interventions for chronic WAD. Pain Res Manag. 2010;15(5):313-322. 6. Kumar S, Ferrari R, Narayan Y. Electromyographic and kinematic exploration of whiplash-type left anterolateral impacts. J Spinal Disord Tech. 2004;17(5):412-422. 7. Hedenstierna S, Halldin P, Siegmund GP. Neck muscle load distribution in lateral, frontal, and rear-end impacts: A three-dimensional finite element analysis. Spine. 2009;34(24):2626-2633. 8. Sterling M. A proposed new classification system for whiplash associated disorders—implications for assessment and management. Man Ther. 2004;9(2):60-70. 9. Clarkson HM. Musculoskeletal assessment: Joint range of motion and manual muscle strength. Lippincott Williams & Wilkins; 2000. 10. Kelly BT, Kadrmas WR, Speer KP. The manual muscle examination for rotator cuff strength. an electromyographic investigation. Am J Sports Med. 1996;24(5):581-588. 11. Kirshblum SC, Burns SP, Biering-Sorensen F et. al. International standards for neurological

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reliability and validity. Phys Ther. 1987;67(12):18671872. 24. Riddle DL, Rothstein JM, Lamb RL. Goniometric reliability in a clinical setting. shoulder measurements. Phys Ther. 1987;67(5):668-673. 25. Youdas JW, Carey JR, Garrett TR. Reliability of measurements of cervical spine range of motion-comparison of three methods. Phys Ther. 1991;71(2):98-104; discussion 105-6. 26. Young BA, Walker MJ, Strunce JB et. al. Responsiveness of the neck disability index in patients with mechanical neck disorders. Spine J. 2009;9(10):802-808. 27. Hoving JL, O’Leary EF, Niere KR et. al. Validity of the neck disability index, northwick park neck pain questionnaire, and problem elicitation technique for measuring disability associated with whiplashassociated disorders. Pain. 2003;102(3):273-281. 28. Childs JD, Cleland JA, Elliott JM, et. al. Neck pain: Clinical practice guidelines linked to the international classification of functioning, disability, and health from the orthopaedic section of the american physical therapy association. JOrthopSports Phys Ther. 2008;38(9):A1-A34. 29. Pangarkar S LP. Conservative treatment for neck pain: Medications, physical therapy, and exercise. Phys Med Rehabil Clin N Am. 2011;22(3):503-520. Accessed 26 January 2015. 30. Kay TM, Gross A, Goldsmith CH et. al. Exercises for mechanical neck disorders. The Cochrane Libr. 2005. 31. Borisut S, Vongririnavarat M, Vachalathiti R et. al. Effects of strength and endurance training of superficial and deep neck muscles on muscle activities and pain levels of females with chronic neck pain. J Phys Ther Sci. 2013;25(9):1157. 32. Gross AR, Goldsmith C, Hoving JL et. al. Conservative management of mechanical neck disorders: A systematic review. J Rheumatol. 2007;34(5):1083-1102. Accessed 26 January 2015.

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