McLean, C., & Graham, T. E. (1998). The impact of gender and exercise on caffeine pharmacokinetics. Medicine and Science in Sports and Exercise, 30(5), Supplement abstract 1380.

Previous research has demonstrated an effect of both gender and exercise on the metabolism of caffeine. Women (N = 8) and men (N = 6) matched for fitness levels and life-styles were tested for eight hours on two occasions, one rest the other exercise, following the ingestion of 6 mg/kg of caffeine (3-9 mg/kg has been shown to be ergogenic).

It was found that exercise and gender had little effect on the absorption, distribution, metabolism, or elimination of caffeine. The amount of caffeine in urine samples was well below the IOC limit of 12 ug/ml.

Implication. Males and females, matched for fitness levels, metabolize caffeine similarly during rest and exercise. Exercise had no effect upon metabolism.

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