Enhancing Sprint Performance in Team Sport Athletes
Effective methods of monitoring and training sprint-running performance for team sport athletes are important for optimising physical preparation for a range of sports. Wearable resistance (WR) training involves attaching external load to the body during physical activity. Recent advances in WR technology have enabled efficient loading methods also of the lower body. The overarching research question of this thesis was “Can WR training enhance sprint-running performance?” The aim of the research was to develop WR speed training guidelines for team sport athletes, based on an understanding of the acute and chronic biomechanical and performance changes that occur with speed training with lower body WR. The objective of Section 1 was to review and assess sprint profiling technologies that can reliably provide insights into some of the kinematic and kinetic determinants of sprint performance. Radar-derived and non-motorised treadmill-derived speed variables typically had acceptable reliability when the average of two sprint trials were analysed. Section 2 involved reviewing two inter-related sprint training methods: lower body WR training and the acute performance enhancement (APE) effects of ballistic exercises on subsequent sprint performance. Potential benefits of the methods and research gaps were identified, which became the focus of subsequent chapters. Section 3 consisted of four cross-sectional studies evaluating the acute biomechanical and sprint performance impacts of lower body WR loading. Early acceleration phase sprint times (≤ 10 m) were not significantly affected by WR up to 5% body mass (BM), but the percentage decrement in maximum velocity phase sprint velocity was approximately equivalent to the magnitude of the lower body loading relative to participant BM (i.e. 3-5%). During both the acceleration phase and the maximum velocity phase lower body WR (3-5% BM) resulted in significantly increased ground contact time (4-6%) and decreased step frequency (-2 to -3%). Wearing moderate (3% BM) WR was associated with increased functional theoretical maximum horizontal ground reaction force (GRF) at the start of acceleration, while heavy (5% BM) WR resulted in significantly lower (-4%) effective vertical GRF during acceleration and lower effective horizontal GRF and power (-5 to -8%) during the maximum velocity phase. There was some evidence that loading a dynamic warm-up or a series of sprints with lower body WR was more effective at achieving APE of sprint acceleration performance compared to loaded jumps. The final section of the thesis included a six-week training study. Similar small improvements in sprint performance (1-3%) and hip strength (3-11%) in the control and WR intervention groups meant that there was no evidence of additional benefit to training with lower body WR compared to traditional speed training. A range of limitations of the training study were discussed. Practical applications covered in the final chapter included: that lower body WR up to 5% BM provides a specific sprint training overload to the mechanical determinants of sprint performance; different loading recommendations were made for the acceleration phase, the maximum velocity phase and for the APE of subsequent unloaded sprint performance. Further training studies are required to determine if longitudinal benefits exist for WR training compared to traditional speed training.