Post-Activation Performance Enhancement in Sprint Performance: The Effect of Time of Day

This study investigated the effect of post-activation performance enhancement (PAPE) on sprint performance according to time of day. Fifteen male athletes performed a 3 × 3 back squat protocol at 85% of one-repetition maximum with 2 min rest between sets as a conditioning activity in the morning (08:00–10:00 h) and evening (17:00–19:00 h) in randomized order, followed by a 30 m sprint test with 10 m intervals measured at 15 s and at 2, 4, 8, 12, and 16 min. Before each conditioning activity, oral body temperature and blood cortisol and testosterone levels were measured, and maximal heart rate, blood lactate, and ratings of perceived exertion were determined. Data were analysed using a 2 × 7 (time of day × measurement time) repeated-measures ANOVA. No time-of-day effect was found in maximal heart rate, lactate, ratings of perceived exertion, or sprint performance (p > 0.05); body temperature was higher in the evening, whereas testosterone and cortisol were higher in the morning (p < 0.05). A significant measurement-time effect was observed for maximal heart rate, lactate, and 10 m, 20 m, and 30 m sprint performance (p < 0.05). The conditioning activity appeared to induce fatigue rather than potentiation.