BRUCE, C. R., M. E. ANDERSON, S. F. FRASER, N. K. STEPTO, R. KLEIN, W. G. HOPKINS, and J. A. HAWLEY. Enhancement of 2000-m rowing performance after caffeine ingestion. Med. Sci. Sports Exerc., Vol. 32, No. 11, pp. 1958–1963, 2000.
To investigate the effect of caffeine ingestion on short-term endurance performance in competitive rowers.
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).
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%).
Ingestion of 6 or 9 mg·kg−1 of caffeine produces a worthwhile enhancement of short-term endurance performance in a controlled laboratory setting.
Exercise Metabolism Group, Department of Human Biology and Movement Science, RMIT University, Bundoora, Victoria 3083, AUSTRALIA; and Department of Physiology and School of Physical Education, University of Otago, Dunedin, NEW ZEALAND
Submitted for publication December 1999.
Accepted for publication February 2000.
Address for correspondence: John A. Hawley, Ph.D., Department of Human Biology and Movement Science, RMIT University, Bundoora, Victoria 3083, Australia; E-mail: email@example.com.