Increase in post activation potentiation in females following a cycling warmup

摘要

Post activation potentiation (PAP) is a phenomenon in which muscular force is acutely enhanced as a result of prior contractile activity. The net augmentation is dependent upon the intensity of the preceding conditioning contraction influencing calcium release and phosphorylation of the regulatory myosin light chain. This phenomenon has been recorded after various types of conditioning contractions, however the interaction of a warmup on PAP remains uncertain and whether this differs between males and females requires consideration. We investigated the effect of a cycling warmup on twitch contractile properties and PAP of the plantar flexors on males and in females using oral contraceptives. A maximal voluntary contraction (MVC) of the plantar flexors preceded and followed a 10-min cycling warmup, where supramaximal twitches were administered prior to, during and after the conditioning contractions. Twitch contractile properties of peak tension (PT), time to peak tension (TPT), half relaxation time (HRT) and contraction duration (CD) were compared between resting and potentiated twitches before and after the warmup. Ultrasonography was used to measure in vivo Achilles tendon architecture. Males were 30% stronger, but voluntary activation did not differ from females (p = .37). In males and females PT increased following the conditioning MVC (p = .03). The degree of potentiation was higher following the warmup in females (25.01%, p = .02) but not males (p = .24). TPT, HRT and contraction duration (p .05) were faster after the warmup and in males (p .001). Achilles tendon elongation was unchanged by the warmup (p = .11). Ten minutes of a cycling warmup reduced TPT, HRT, and CD in both males and females without altering the tendon. The degree of PAP was higher in females than males following the warmup. This difference might be associated with altered calcium kinetics of females on oral contraceptives as well as higher proportion of type I fibres in the active muscles.