0955658 Biomechanical assessment and determinants of punching in boxers Seth Lenetsky PhD A thesis submitted to Auckland University of Technology in fulfilment of the requirements for the degree of Doctor of Philosophy (PhD) 2018 School of Sport and Recreation I 0955658 Abstract Punching is a fundamental human movement that is the defining action of many combat sports, most of all boxing where it is the primary method of attack. This thesis investigated the biomechanics and determinants of punching to answer the question, “What defines effective punching in boxing?” The first chapter of the thesis expanded on these themes, as well as identifies current gaps in the literature relating to the analysis of punching in boxing. Chapter two was a narrative review of methods used to assess impact kinetics and the contributors to impact kinetics in combat sports. The third chapter was a narrative review on effective mass, an impact variable of interest in the literature. The chapter focused on defining the variable and the methods proposed to maximise effective mass. The review found that effective mass was the inertial contribution of a fighter to impact. Additionally, the review found that double peak muscle activation is currently the only process proposed in the literature to increase effective mass. There is a potential gap in the literature regarding continued force application by the lower body during impact. Chapter four, a qualitative study of experienced boxing coaches exploring their views on effective punching performance. The results of the study are in agreement with Chapter two in that the lower body’s contribution was key to producing an effective punch. Chapter five presents an original method to measure impact kinetics using practical, simple, affordable, and relevant equipment. Reliability test statistics determined that all measures had acceptable reliability (CV ≤ 4.6%). Validity was determined via linear regression of a spectrum of loads and coefficient of determination. All variables were found to have a good fit to the model (푟2 ≥ 0.92) except for rate of force development (푟2 ≥ 0.57). Chapter six, assessed the reliability of the method described in Chapter five on a cohort of experienced boxers and untrained participants tested intra and intersession. Reliability statistics were small (ICC < 0.67 and CV < 10%) to moderate (ICC < 0.67 or CV < 10%) and technical error of measurement was moderate (TEM = 0.60 – 1.19). Chapter seven was a mixed method analysis of ground reaction forces, electromyography, and high-speed video to define the phases of straight and hook punches. The definition of phases was a novel contribution to the punching literature, identifying three phases for straight punches (initiation, execution, and impact) and four for hook punches II 0955658 (wind-up, initiation, execution and impact). The chapter used qualitative and quantitative methods to discover the uniqueness of each punch type and the differences between lead and rear hand punches of the same punch type. Chapter eight, the final experimental study of the thesis, used the findings from throughout this research to identify the determinants of impact kinetics in straight and hook punches. Findings from the study further reinforce the uniqueness of each punch type as no individual variable determined impact kinetics across them. There were general commonalities, as the majority of determinants were found in the lower body (19 of the 28), confirming the findings of Chapter Two, and those related to the upper body indicated that relaxation of the musculature was key to optimising impact kinetics. Results relating to effective mass found that double peak muscle activation had no correlation, while the lower body had meaningful correlations. This finding confirms the theory introduced in Chapter Three regarding the lower body’s continued force application during impact, but conflicts with current theories relating to double peak muscle activation. The final chapter (nine) is a summary of findings, areas for future research, and practical applications. This PhD has contributed knowledge regarding the understanding of effective mass in punching, the role of ground reaction forces as a key to punching, the kinematic and kinetic events of punching in a phase model, and the determinants of impact kinetics in straight and hook punching. III 0955658 Table of contents ABSTRACT ........................................................................................................... II LIST OF FIGURES .............................................................................................. VII LIST OF TABLES ................................................................................................ VIII LIST OF EQUATIONS ......................................................................................... IX LIST OF APPENDICES ........................................................................................ IX ATTESTATION OF AUTHORSHIP ........................................................................ XI CANDIDATE CONTRIBUTIONS TO CO-AUTHORED PUBLICATIONS ............... XII ACKNOWLEDGEMENTS ................................................................................. XIV ETHICAL APPROVAL ...................................................................................... XVII LIST OF COMMON ABBREVIATIONS ........................................................... XVIII CHAPTER 1 - INTRODUCTION AND RATIONALE ............................................. 19 Background and importance 19 Rational and significance 24 Thesis aims 25 Thesis structure 26 CHAPTER 2 - ASSESSMENT AND CONTRIBUTORS OF PUNCHING IMPACT KINETICS IN COMBAT SPORTS: IMPLICATIONS FOR STRENGTH AND CONDITIONING ............................................................................................... 30 Reference, Author contribution, Preface, and Abstract 30 Introduction 31 Methods 31 Measurement and analysis of punching impact kinetics 31 Contributors to punching impact kinetics 34 Potential strength and conditioning strategies for improvement of punching impact kinetics 36 Practical applications 38 Conclusion 43 IV 0955658 CHAPTER 3 - IS EFFECTIVE MASS IN COMBAT SPORTS PUNCHING ABOVE ITS WEIGHT? ........................................................................................................... 44 Reference, Author contribution, Preface, and Abstract 44 Introduction 45 Effective mass 46 “Double peak muscle activation” in review 54 Practitioner interventions 56 Conclusion 57 CHAPTER 4 - COACHING BOXING: AN EXPERT ANALYSIS OF PUNCHING PERFORMANCE IN BOXERS ............................................................................. 58 Reference, Author contribution, Preface, and Abstract 58 Introduction 60 Methods 61 Results 63 Discussion 66 Conclusion 70 Acknowledgements 71 CHAPTER 5 - A PRACTICAL METHOD FOR THE MEASURMENT OF STRIKING IMPACT KINETICS VIA ACCELEROMETRY AND INERTIAL MODELLING .......... 72 Reference, Author contribution, Preface, and Abstract 73 Introduction 74 Inertial modelling of striking bag 76 Methods 82 Statistical analysis 84 Results 85 Discussion 88 Conclusion 89 CHAPTER 6 - VARIABILITY AND RELIABILITY OF PUNCHING IMPACT KINETICS IN UNTRAINED PARTICIPANTS AND EXPERIENCED BOXERS ......................... 91 Reference, Author contribution, Preface, and Abstract 91 Introduction 92 Methods 93 Statistical analysis 96 V 0955658 Results 96 Discussion 98 Conclusion 99 CHAPTER 7 - DEFINING THE PHASES OF BOXING PUNCHES: A MIXED METHOD APPROACH ..................................................................................... 101 Reference, Author contribution, Preface, and Abstract 101 Introduction 102 Methods 104 Results 107 Discussion 126 Conclusions 128 CHAPTER 8 A & B - GROUND REACTION FORCES AND ELECTOMYOGRAPHIC DETERMINANTS OF PUNCHING IMPACT KINETICS IN MALE BOXERS ................................................................................................ 129 Reference, Author contribution, Preface, and Abstract 129 Introduction 130 Methods 132 Results 140 Discussion 165 Conclusion 181 CHAPTER 9 - CONCLUSION, DIRECTION OF FUTURE RESEARCH, AND PRACTICAL APPLICATIONS .......................................................................... 183 Conclusion 183 Synthesis of Findings 186 Direction of future research 187 Practical applications 188 REFERENCES ................................................................................................... 190 APPENDICES ................................................................................................... 198 VI 0955658 List of figures Figure 1. Thesis structure. ................................................................................... 26 Figure 2. Differences between an actual strike and the ballistic modelling of effective mass. ...................................................................................................... 48 Figure 3. A general representation of the double peak activation pattern throughout a rear hand punch. ........................................................................... 55 Figure 4. A graphical representation of the key variables. .................................. 77 Figure 5. Visualisation of Equation 19. ............................................................... 81 Figure 6. Output of the custom-made LabVIEW programme. ........................... 84 Figure 7. Linear regressions comparing the pendulum mass and the dependent variables. .............................................................................................................