View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by Carolina Digital Repository THE INFLUENCE OF TECHNIQUE ON THROWING PERFORMANCE AND INJURY RISK IN JAVELIN THROWERS Steven Leigh A dissertation submitted to the faculty of the University of North Carolina at Chapel Hill in partial fulfillment of the requirements for the degree of Doctor of Philosophy in the Curriculum of Human Movement Science. Chapel Hill 2012 Approved by: Bing Yu, PhD Jesus Dapena, PhD Michael Gross, PT, PhD Li Li, PhD Joseph Myers, PhD, ATC ABSTRACT STEVEN LEIGH: The Influence of Technique on Throwing Performance and Injury Risk in Javelin Throwers (Under the direction of Bing Yu) The overall objective of this dissertation was to understand the effects of elite javelin throwers’ techniques on their athletic performance and their risk for injury. Javelin throwing is a complex, multi-joint task that requires great coordination, muscular strength, and control to generate the forces necessary to propel implements at high velocities. A javelin thrower’s technique has crucial effects on the release variables that determine their performance. The need to generate high release speeds means that javelin throwing techniques exert significant musculoskeletal stress to multiple joints, which may cause acute and overuse injuries. Since an athlete’s technique affects both their performance and their injury risk, it is necessary to understand the inter-relationships between technique, performance, and injury in throwing events, such as the javelin. Three-dimensional kinematic and kinetic data were reduced from the video images of elite javelin throwers competing in the USA Track and Field National Outdoor Championships. Cross-sectional and longitudinal, subject-specific statistical analyses were performed to investigate the relationships between javelin throwing technique and performance, to further investigate potential risk factors for injuries, to investigate the differences in technique between injured and uninjured athletes, and to classify technique variables based on their relationship with performance or injury. ii Technique variables that were associated with differences in performance and injury were identified. Differences were found between males and females, and for specific subjects. These differences do not mean that javelin throwing technique was different between genders or subjects. In general, it is important for javelin throwers to effectively transfer run-up momentum and throwing arm action into great release speed, and to control the release. Great joint forces were observed in javelin throwers, were associated with movements of the shoulder and elbow, and are the mechanism for javelin throwing injury. Some technique variables were identified that were only associated with either performance or injury. These variables may be modified to improve performance without increasing injury risk, or to decrease injury risk without affecting performance. For technique variables that affect both injury prevalence and performance, other training methods and treatments may be necessary to allow for improved performance without increased injury risk. iii ACKNOWLEDGEMENTS This project was financially supported by USA Track & Field, a Smith Graduate Research Grant from the Graduate School at The University of North Carolina at Chapel Hill, and a Matching Dissertation Grant from The International Society of Biomechanics. iv TABLE OF CONTENTS LIST OF TABLES......……...………………...………….....…............................................. vii LIST OF FIGURES……..…………………………............................................................... ix LIST OF ABBREVIATIONS AND SYMBOLS...……….....……………...……............…. xi Chapter I. INTRODUCTION............................................................................................................ 1 Background and Significance…...……………................……..................…..........……. 1 Statement of the Problem…..………………….................…......................….........…… 7 Specific Aims of the Dissertation.…..………………...............…........…....……........… 8 Definitions of Key Terms..……………....……..........………...........………........……. 10 II. REVIEW OF LITERATURE…………............…………………………….........……. 15 Javelin Throwing Technique............................................................................................ 15 Javelin Throwing Performance........................................................................................ 22 Biomechanical Factors that Affect Performance in Javelin Throwing............................ 24 The Influence of Technique on Javelin Throwing Performance..................................... 41 Injuries in Over-arm Throwing........................................................................................ 44 The Influence of Technique on Javelin Throwing Injuries.............................................. 54 v III. METHODS………………………………...........………………........…………........... 55 Subjects............................................................................................................................ 55 Data Collection................................................................................................................ 57 Data Reduction................................................................................................................. 62 Data Analysis................................................................................................................... 75 IV. RESULTS..………………………………................……………………….................. 82 Injury Survey................................................................................................................... 82 Kinematic Data Screening............................................................................................... 83 Technique and Performance….…................................................................................... 84 Technique and Injury……............................................................................................... 93 V. DISCUSSION………………………….……………………………............................. 98 Technique and Performance...………………................................................................. 98 Technique and Injury...................................................................................................... 122 Limitations & Future Studies.....…................................................................................ 144 Summary........................................................................................................................ 147 Tables………......................................................................................................................... 149 Figures……........................................................................................................................... 178 References……...................................................................................................................... 210 vi LIST OF TABLES Table 3.1 Subject Demographics........................................................................................ 149 4.1 Injury Survey...................................................................................................... 150 4.2 Inter- and Intra-Rater Reliability........................................................................ 151 4.3 Female Performance Correlations...................................................................... 153 4.4 Male Performance Correlations…...................................................................... 154 4.5 Female Official Distance Multiple Regression................................................... 155 4.6 Male Official Distance Multiple Regression...................................................... 156 4.7 Female Release Speed Multiple Regression....................................................... 157 4.8 Male Release Speed Multiple Regression.......................................................... 158 4.9 Female Aerodynamic Distance Multiple Regression......................................... 159 4.10 Male Aerodynamic Distance Multiple Regression............................................. 160 4.11 Longitudinal Subject’s Descriptive Statistics………......................................... 161 4.12 Subject F1 Performance Correlations................................................................. 162 4.13 Subject F2 Performance Correlations................................................................. 163 4.14 Subject F3 Performance Correlations................................................................. 165 4.15 Subject M1 Performance Correlations................................................................ 167 4.16 Subject M2 Performance Correlations................................................................ 168 4.17 Subject M3 Performance Correlations................................................................ 169 4.18 Shoulder and Elbow Forces and Torques........................................................... 170 4.19 Shoulder and Elbow Force and Torque Correlations…...............…….............. 171 vii 4.20 Injured Females Technique Differences…………………................................. 172 4.21 Injured Males Technique Differences…………………………........................ 173 4.22 Female Technique Groupings for Performance or Injury……........................... 174 4.23 Male Technique Groupings for Performance or Injury…............….................