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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.

Purpose: 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 [ O2peak] 4.7 /- 0.4 L[middle dot]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[middle dot]kg-1 body mass) or placebo. Trials were preceded by a standardized warm-up (6 min at 225 /- 39 W; 75 /- 7.7% O2peak).

Results: Urinary caffeine concentration was similar before ingestion (~1 mg[middle dot]L-1) but rose to 6.2 /- 3.6 and 14.5 /- 7.0 mg[middle dot]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[middle dot]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[middle dot]kg-1 of caffeine produces a worthwhile enhancement of short-term endurance performance in a controlled laboratory setting.

(C) 2000 Lippincott Williams & Wilkins, Inc.