External mechanical work done during the acceleration stage of maximal sprint running and its association with running performance.

This study aimed to elucidate how external mechanical work done during maximal acceleration sprint running changes with increasing running velocity and is associated with running performance. In twelve young males, work done at each step over 50 m from the start was calculated from mechanical energy changes in horizontal anterior-posterior and vertical directions and was divided into braking (- and , respectively) and propulsive ( and , respectively) phases. The maximal running velocity () appeared at 35.