This study was conducted to evaluate the influence of excessive sweating during long-distance
running on the urinary concentration of caffeine after the intake of a large amount
of caffeine. Nine endurance-trained athletes participated in a randomised cross-over
study in which 450 mg caffeine were taken with and without exercise. Exercise consisted
of running for 30 min on a treadmill at 75% of maximum heart rate, one hour after
intake of caffeine. This endurance exercise caused a decrease in the urine flow as
well as in the amount of caffeine excreted in urine. The combined effect of both these
decreases is that the concentrations of caffeine detected in urine were similar with
and without exercise. The maximum caffeine concentration detected in any urine sample
was 11.9 (ig/ml without exercise and 10.4 u.g/ml with exercise. It can be concluded
that excessive sweating during long-distance running did not enhance the urinary caffeine
concentration.
Sport - caffeine - endurance exercise
