Kinematic and Kinetic Comparison of Sprint-Specific Exercises: Impact on Maximal Sprint Acceleration Training.

Sprint-specific exercises (SSEs) are believed to train force, power and/or velocity qualities involved in the acceleration phase of sprinting. However, the kinetics and the kinematics of such exercises have never been explored. The aim of this study was to compare mechanical variables (horizontal and vertical forces, horizontal velocity of the centre of mass and the ratio of force) between SSEs and an all-out 40-m sprint acceleration (Sref). These variables were measured over each situation (Sref and 14 SSE) using six track-embedded force plates. The horizontal forces and velocities were either lower or equal to those of the Sref (SSE grand average deviation from FVP ~ -0.29 N∙kg-1 for force; SSE grand average from Sref ~ -0.14 m∙s-1 for velocity), while vertical force output was mostly greater in the SSE than the Sref (SSE mean deviation from Sref ~0.49 N∙kg-1). The ratio of force was lower or equal for the SSE compared to Sref. Despite large inter-individual variability, these SSEs seem useful to stimulate vertical force production, and not horizontal as hypothesised by coaches. These results suggest the importance of analysing the SSE used during training, from a force-velocity point of view, to better characterize their effectiveness.