PRE-TENSING DOES NOT BENEFIT SPRINT STARTS
Dapena, J., Gutiarrez-DaVila, M., & Campos, A. (2006). The effect of muscular pre-tensing on the sprint start. Medicine and Science in Sports and Exercise, 38(5), Supplement abstract 745.
This study examined the horizontal forces developed by sprinters through the feet and hands in starts using large and small amounts of pre-tensing. Male sprinters (N = 19) performed a “pre-tensed” start and a “conventional” start, respectively with large and small forces exerted against the blocks in the “set” position.
The forward force received by the feet in the “set” position was significantly higher in the pre-tensed start than in the conventional start. The pre-tensed start lasted slightly longer than the conventional start and used a slightly longer horizontal range of motion but produced no statistical difference in horizontal velocity at the end of the start. At the onset of motion and for a short period afterward, the propulsive forces exerted on the feet were larger in the pre-tensed starts than in the conventional starts, but the resistive forces exerted on the hands were also larger during this period. This suggests that limitations in the capability for quick deactivation of the arm muscles after the onset of motion negated the advantage of the larger propulsive forces of the legs.
Implication. Pressing the feet hard against the blocks while waiting for the gun is not advantageous in the sprint start.
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