Postactivation potentiation in endurance-trained male athletes

Purpose: The purpose of the study was to determine whether postactivation p otentiation (PAP) was enhanced in the trained muscles of male endurance ath letes. Methods: Triathletes (TRI), distance runners (RUN), active controls (AC), and sedentary control subjects (SED) (N = 10 per group) performed 10- s maximal isometric contractions (MVC) of the elbow extensor and ankle plan tarflexor muscles. Maximal twitch contractions were evoked (percutaneous st imulation) before and during a 5-min period after the MVC. PAP was measured as the percentage change in peak twitch torque post-MVC. Results: TRI, who train both upper and lower limb muscles, had enhanced (relative to SED) PA P in both elbow extensor and plantarflexor muscles. In RUN, who train only the lower limbs, enhanced PAP was restricted to the plantarflexors. AC, who se main activity was upper and lower limb weight training, also had enhance d PAP in both muscle groups, although the enhancement in the plantarflexors was nor as great as in TRI and RUN. Conclusion: PAP is enhanced in enduran ce athletes. Enhanced PAP may counteract fatigue during endurance exercise. The mechanism(s) responsible for the enhanced PAP remain to be determined.