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 center dot 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 center dot m center dot kg(-1)) and placebo (1.13 +/- 0.10 N center dot m center dot 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 x supplement interaction with values being significantly higher from the sixth sprint (torque factor 1.0 N center dot m center dot 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 center dot m center dot kg(-1) and thereby failing to elicit W-max, have failed to find an effect of caffeine on sprinting performance.