Analysis of the segmental contribution in sprint start performance

Abstract

In this study, a calculation system has been applied to examine the contribution of five groups of body segments to the horizontal displacement of the Center of Mass (CM) in block starts and to explore their relationship with the horizontal velocity of the CM at the end of 0.1s and 0.312s of the acceleration phase. Twenty sprinters with a personal record in 100 m of 11.05 ± 0.31s have participated. The horizontal reaction forces were recorded using two force platforms synchronized to a video camera that recorded the sagittal plane of motion. The contribution of the legs at the end of the acceleration phase was 91.2 ± 2.4% and the free leg was 8.1 ± 1.0%. The trunk + head is the first group of segments that begins to contribute to the horizontal displacement of the CM, reaching 39.3 ± 24.3% in the first 0.1s. His quick forward contribution causes a reactive backward force that could be related to an ankle dorsiflexion of 8º ± 3º and 9º ± 3º, back and front leg, respectively. The early contribution of the head + trunk has been positively correlated with the horizontal velocity at the end of the acceleration phase (r = 0.622, p = 0.003), which confirms its importance as a performance indicator in block starts.