Caffeine supplementation and peak anaerobic power output

The aim of this study was to investigate the effects of caffeine supplementation on peak anaerobic power output (W max ). Using a counterbalanced, randomised, double-blind, placebo-controlled design, 14 well-trained men completed three trials of a protocol consisting of a series of 6-s cycle ergometer sprints, separated by 5-min passive recovery periods. Sprints were performed at progressively increasing torque factors to determine the peak power/torque relationship and W max . Apart from Trial 1 (familiarisation), participants ingested a capsule containing 5 mg·kg −1 of caffeine or placebo, one hour before each trial. The effects of caffeine on blood lactate were investigated using capillary samples taken after each sprint. The torque factor which produced W max was not significantly different (p ≥ 0.05) between the caffeine (1.15 ± 0.08 N·m·kg −1 ) and placebo (1.13 ± 0.10 N·m·kg −1 ) trials. There was, however, a significant effect (p < 0.05) of supplementation on W max , with caffeine producing a higher value (1885 ± 303 W) than placebo (1835 ± 290 W). Analysis of the blood lactate data revealed a significant (p < 0.05) torque factor × supplement interaction with values being significantly higher from the sixth sprint (torque factor 1.0 N·m·kg −1 ) onwards following caffeine supplementation. The results of this study confirm previous reports that caffeine supplementation significantly increases blood lactate and W max . These findings may explain why the majority of previous studies, which have used fixed-torque factors of around 0.75 N·m·kg −1 and thereby failing to elicit W max , have failed to find an effect of caffeine on sprinting performance.