Effect of postactivation potentation on dynamic knee extension performance

• Published in: European journal of applied physiology Vol. 83; no. 6
• Main Authors: Roderich, Gossen E, Sale, D G
• Format: Journal Article
• Language: English
• Published: 01.12.2000
• ISSN: 1439-6319

Six men and four women performed, in separate trials, maximal dynamic kinee extensions with loads of 15%, 30%, 45% and 60% of maximal isometric knee extension peak torque (MVC). The dynamic extensions were done after postactivation potentiation (PAP) had been induced with a 10-s MVC, and in a control trial without PAP. PAP, measured as the increased in evoked twitch torque, was 53 (4%) (SE) and 43 (3%) at the time of the first and second extensions with each load. PAP failed to increase the attained peak velocity with any load; on the contrary, there was a trend for peak velocity to decrease in the first extension, which occurred approx 15s after the 10-s MVC. The results suggest that fatigue produced by the 10-s MVC suppressed any benefit that could be derived from the induced PAP. A surface electromyogram (EMG) recorded from one muscle of quadriceps femoris gave no indication of activation failure in the first knee extension; however, activation impairment specific to the rate of force development cannot be ruled out. It is concluded that the strategy employed, namely of having knee extensions performed soon after the 10-s MVC to maximise PAP at the time of performance, was unsuccessful because there had been insufficient time for recovery from fatigue. It is possible that a longer recovery time, even at the cost of a diminished PAP, may have proved beneficial.