Effect of postactivation potentiation on the maximal voluntary isokinetic concentric torque in humans.

The purpose of this study was to examine whether postactivation potentiation (PAP) influences dynamic torque development in humans. Nine recreationally active men performed sets of 3 maximal isokinetic concentric plantar flexions at 180 degrees/second in the following sequence: before and immediately (5 seconds) after a 10-second maximal voluntary contraction (MVC) and then every 1 minute until the 5-minute point, followed by 1 more stimulation at the 10-minute point. Twitch responses were recorded before every set of 3 concentric contractions to examine whether the PAP exists. The twitch and concentric torques were potentiated at 0 through 5 minutes and 1 through 3 minutes post-MVC, respectively (p < 0.05), whereas there was no significant difference in concentric torque in the control (without MVC) condition (p > 0.05). For electromyographic signals during concentric contractions, muscle activity of the medial gastrocnemius was significantly depressed only immediately after the conditioning MVC (p < 0.05). These results indicate that a brief maximal voluntary isometric contraction enhances voluntary dynamic performance through PAP, within proper recovery interval. From a practical point of view, in sports activities we suggest undertaking PAP through high-intensity contractions 1 to 3 minutes before voluntary ballistic or plyometric actions for improved performance.