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Middle-distance athletes are faced with a unique challenge to generate high running velocities (between 6.00 and 8.00 m∙s-1) while making movements as economical as possible (Williams & Cavanagh, 1987). Research suggests that 54% of the variation in running economy can be attributed to gait and spring-mass characteristics. The aims of this thesis were to establish a valid means of measuring gait and spring-mass characteristics away from the laboratory environment and then to provide a biomechanical evaluation of middle-distance running during competition and training in order to identify gait and spring-mass characteristics that influence performance time. Accordingly this thesis has demonstrated that high-speed, Optojump and laser distance measurement (LDM) device all provided a valid measurement of gait and spring-mass characteristics. Spring-mass characteristics obtained through mathematical modelling (estimations based on high-speed video data only) during running were comparable to the gold standard direct measurement (using a force platform). These mathematical models allow for estimations of Kvert and Kleg to be reported away from the laboratory environment on an outdoor 400 m synthetic athletics track. During outdoor track competition international-level athletes achieved a lower performance time as a consequence of a longer step length and lower Kvert¬ and Kleg. For the first time this suggests that a longer step length, greater knee flexion, lower Kvert and Kleg are differentiating factors associated with a reduced middle-distance performance time. Whereas, over a single training session and training block regional-level athletes maintained running velocity by significantly increased step frequency and a reduction in Kvert/BW. Overall, this thesis implies that middle-distance training should monitor how athletes sustain a high running velocity with more emphasis placed on step length to develop competitive performance by increasing flight distance. To increase the travel during flight it is suggested that athletes increase vertical ground reaction forces through plyometric exercises (e.g. stretch-shortening cycle) and continual development of middle-distance training history. |
