Athletic performance is one topic which has been relatively unexplored in the area of biomechanics despite the fact that biomechanical factors will play a vital role in an athlete's performance. The main purposes of this investigation were to determine the mechanical energy contribution of the lower extremity joints to the activities of running, sprinting, long jumping and vertical jumping and to determine if reducing the amount of energy lost by an athlete at a joint increases athletic performance.

The results of this study indicate that the ankle joint was the largest energy absorber and the largest energy generator of all the lower extremity joints during the stance phase of running, sprinting, long jumping and vertical jumping. The knee joint played a larger role than the hip joint during running but the hip had a larger influence than the knee during sprinting. For both the long jump and the vertical jump, the knee joint had the same relative contribution to both, whereas the hip joint made a larger relative contribution to the long jump than it did to the vertical jump. The metatarsophalangeal joint was a large energy absorber for all activities and generated only a minimal amount of energy at take-off due to a lack of extension. Additional results showed that a reduction in the amount of energy absorbed at the metatarsophalangeal joint resulted in an increase in vertical jump height performance with the increase in jump height being closely related to the decrease in energy lost.

The information provided in this dissertation contributes to the understanding of each joint's role in the performance of different athletic activities. The information may be useful in increasing performance by developing appropriate training programs, modifying athletic movements or developing athletic equipment which reduces the amount of energy lost by an athlete.