Bidwell, W. K., Woolf, K., Carlson, A., & Vaughan, L. A. (2006). Effect of caffeine as an ergogenic aid on anaerobic exercise performance in highly trained athletes. Medicine and Science in Sports and Exercise, 38(5), Supplement abstract 1331.

Caffeine is commonly ingested as an ergogenic aid by athletes to enhance performance. The research literature documents that caffeine may improve performance in aerobic exercises. However, the evidence for caffeine enhancing anaerobic performance is much more conflicting.

The study examined the effects of caffeine (5g/kg body weight vs. placebo) on anaerobic exercise performance in highly trained male athletes (N = 18). Ss made two study visits one week apart. On each occasion, Ss avoided caffeinated products for 48 hours and provided a urine sample at baseline to assess for caffeine. Fasting blood samples [free fatty acids, glucose, cortisol, lactate, and insulin] were collected from each S. Ss ingested a shake (caffeine or placebo), consumed a light breakfast, and then completed three exercise tests in random order (leg press, chest press, and the Wingate test) 60 minutes later. Rate of perceived effort was recorded after each exercise test. Blood and urine (caffeine) samples were also taken after the final exercise test.

No differences between the two trials were found in the baseline blood parameters. Total weight lifted (weight x reps) for the chest press was significantly higher in the caffeine trial compared to the placebo trial. No differences were found in the leg press between the two trials. However, peak power during the Wingate test was significantly higher in the caffeine trial compared to the placebo trial. The post-exercise blood concentrations of cortisol, glucose, and insulin were significantly higher in the caffeine trial compared to the placebo. No differences were seen in the post-exercise free fatty acids and lactate blood concentrations between the two trials. No differences were found in the rating of perceived effort between the caffeine and placebo trials.

Implication. Caffeine improved peak power during the Wingate test and increased total weight lifted during the chest press in highly trained male athletes. On this occasion, caffeine enhanced anaerobic exercise performance.

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