Caffeine Exerts Neither Ergogenic nor Hypoalgesic Effects on Sprint Interval Exercise with Intensive Exercise-Induced Muscle Pain.

Abstract

Sprint interval exercise can cause transient, intense exercise-induced pain (EIP) during and several minutes after the activity. A hypoalgesic strategy for high-intensity exercise, such as sprint interval exercise, against EIP is necessary to maintain exercise habituation and improve training quality/exercise performance. Preexercise caffeine supplementation, a well-known ergogenic strategy, may improve sprint performance and alleviate EIP as the hypoalgesic strategy. However, whether preexercise caffeine supplementation exhibits both the ergogenic effect on sprint interval performance and the hypoalgesic effect on intensive EIP during and several minutes after high intensity sprint interval exercise remains unknown, and thus we investigated to clarify those points. In this double-blind, randomized, crossover trial, sixteen male collegiate athletes performed 3 sets of 30-sec all-out Wingate pedaling exercises at 2-min intervals. Participants ingested 6 mg·kg^-1 caffeine or placebo via capsules at 60 min prior to exercise. Quadriceps EIP was measured using a visual analogue scale during and up to 20 min after exercise. The results showed that caffeine did not significantly affect peak or mean power during sprint interval exercise (peak power: P = 0.196, η_p ² = 0.11, mean power: P = 0.157, η_p ² = 0.13; interaction). No significant interactions were also found for quadriceps EIP during (P = 0.686, η_p ² = 0.03) and immediately after exercise (P = 0.112, η_p ² = 0.12), nor for changes in physiological responses (blood lactate and ammonia concentrations) and caffeine-induced side effects (all P > 0.05). In conclusion, caffeine had no ergogenic or hypoalgesic effects on sprint interval exercise with intensive EIP.