To investigate the effect of caffeine ingestion on short-term endurance performance in competitive rowers.Methods
In this randomized double-blind crossover study, eight competitive oarsmen (peak oxygen uptake [V̇O2peak] 4.7 ± 0.4 L·min−1, mean ± SD) performed three familiarization trials of a 2000-m rowing test on an air-braked ergometer, followed by three experimental trials at 3- to 7-d intervals, each 1 h after ingesting caffeine (6 or 9 mg·kg−1 body mass) or placebo. Trials were preceded by a standardized warm-up (6 min at 225 ± 39 W; 75 ± 7.7% V̇O2peak).Results
Urinary caffeine concentration was similar before ingestion (∼1 mg·L−1) but rose to 6.2 ± 3.6 and 14.5 ± 7.0 mg·L−1 for the low and high caffeine doses, respectively. Plasma free fatty acid concentration before exercise was higher after caffeine ingestion (0.29 ± 0.17 and 0.39 ± 0.20 mM for 6 and 9 mg·kg−1, respectively) than after placebo (0.13 ± 0.05 mM). Respiratory exchange ratio during the warm-up was also substantially lower with caffeine (0.94 ± 0.09 and 0.93 ± 0.06 for the low and high dose) than with placebo (0.98 ± 0.12). Subjects could not distinguish between treatments before or after the exercise test. Both doses of caffeine had a similar ergogenic effect relative to placebo: performance time decreased by a mean of 1.2% (95% likely range 0.4–1.9%); the corresponding increase in mean power was 2.7% (0.4–5.0%). Performance time showed some evidence of individual differences in the effect of caffeine (SD 0.9%; 95% likely range 1.5 to −0.9%).Conclusions
Ingestion of 6 or 9 mg·kg−1 of caffeine produces a worthwhile enhancement of short-term endurance performance in a controlled laboratory setting.