Can a high-intensity contraction be enhanced bya conditioning contraction? insight from the relationship between shortening velocity of muscle fibers and postactivation potentiation

The magnitude of twitch torque increases after a high-intensity contraction of the same muscle (conditioning contraction). This phenomenon is called postactivationpotentiation (PAP). Recently, it has been shown that the maximal voluntary concentric torque or power attained during the maximal voluntary concentric contraction can be increased by a conditioning contraction, suggesting that conditioning contractions are effective on not only twitch but also on maximal voluntary contractions. In contrast, some studies have reported that a conditioning contraction had no potentiation effect on subsequent electrically-evoked maximal isometric force. This discrepancy among previous studies may be attributable to differences in the mode of contraction (i.e., isometric, concentric or eccentric), which can affect the extent of PAP. Therefore, the main purpose of this study was to examine the influence of these aforementioned factors on the extent of PAP, and to discuss the applications of a conditioning contraction to high-intensity contractions.