Effect of maximum voluntary isometric contraction of the triceps surae muscle on a subsequent drop jump

PurposePre-muscle contraction improves sports performance because post-activation potentiation (PAP), induced by a previous intense voluntary contraction (conditioning contraction), amplifies the subsequent target muscle contraction. This study aims to examine the influence of conditioning contraction on the performance of ballistic motion, particularly on the stretch-shortening cycle (SSC). MethodsFourteen male university students specializing in athletic jumping events performed a drop jump from a height of 0.3 m. Maximal voluntary isometric plantarflexion for 6 seconds was considered a conditioning contraction. We set two conditions: in the PAP condition, participants performed a conditioning contraction 10 s before the drop jump, and in the control condition, they simply performed the drop jump. After 10 minutes of rest from the reference drop jump, both conditions were performed. A 3D motion analysis system, force plates, and surface electromyography were used to record the jump data. ResultsIn the PAP conditions, the jump height and velocity of the center of gravity increased by 4 cm and 14 cm/s, respectively. Lower limb torque increment was observed only in the ankle joint between the PAP and control conditions (0.31 Nm/kg). However, there was no change in the magnitude of muscle activity based on the electromyogram. ConclusionOur study showed that PAP could potentiate the contraction mechanism under excitation-contraction coupling, irrespective of the effect on the central nervous system. Therefore, PAP enhances jump performance by improving SSC.