Differences in support leg kinetics between non-sprinters and sprinters during maximal speed sprinting

Abstract

In general, non-sprinters (team sport athletes) exhibit lower sprint performance than sprinters. The differences in spatiotemporal and ground reaction force (GRF) variables between non-sprinters and sprinters have been reported previously. The differences may not simply reflect sprint ability but rather sport-specific characteristics, implying variation in joint kinetics. Therefore, this study aimed to examine the differences in lower limb joint kinetics during the stance phase of maximal speed sprinting between non-sprinters and sprinters. Twenty-six male non-sprinters (13 soccer and 13 baseball players) and 12 male sprinters participated. Sprint data around the maximal speed phase were measured using a motion capture system and force plates. Kinetic variables of the lower limb joints and GRFs during the stance phase were compared between the two groups. As a result, maximal sprint speed was lower in non-sprinters (8.53 ± 0.38 m/s) than in sprinters (9.62 ± 0.25 m/s). The vertical and anteroposterior GRFs throughout the stance phase were smaller in non-sprinters than in sprinters. Moreover, compared with sprinters, non-sprinters exhibited smaller ankle plantarflexion torques but larger knee and hip extension torques. The results indicate that knee and hip extension torques compensate for insufficient ankle plantarflexion torque in generating vertical and anteroposterior GRFs in non-sprinters. The differences in sprint mechanics between non-sprinters and sprinters might be influenced by differences in sports specificities. Therefore, increasing ankle plantarflexion torque may improve maximal-speed sprint performance in non-sprinters; however, the direct transfer of this suggested modification to short sprints involving frequent changes of direction requires careful consideration.