THE EFFECT OF DIFFERENT DOSAGES OF CAFFEINE ON ENDURANCE PERFORMANCE TIME

The effect of different dosages of caffeine (0 - 5 - 9 - 13 mg . kg bo dy weight(-1)) on endurance performance was examined. Nine well-traine d cyclists participated in this study (VO(2)max 65.1 +/-2.6 ml . kg(-1 ). min(-1)). Caffeine capsules were administered in random order and d ouble-blind. One hour after capsule ingestion, subjects cycled until e xhaustion at 80% Wmax on an electromagnetically braked cycle ergometer . Blood samples were taken before, during and after the exercise test. Before and after the test a urine sample was obtained. A significant increase in endurance performance was found for all caffeine tests com pared to placebo (endurance time 47+/-13, 58+/-11, 59+/-12 and 58+/-12 min for 0, 5, 9 and 13 mg . kg(-1) body weight, respectively). No dif ferences were found in endurance performance between the three caffein e dosages which indicates that no dose-response relation of caffeine a nd endurance performance was found. An increased free fatty acid and g lycerol concentration was found after caffeine consumption compared wi th placebo. The mean urinary caffeine concentrations after exercise we re 4.8+/-1.8, 8.9+/-5.2 and 14.9+/-6.9 mu g . ml(-1) urine for 5, 9 an d 13 mg of caffeine . kg(-1) body weight. Only the lowest dose of caff eine resulted in urine caffeine concentrations below the doping limit of the International Olympic Committee of 12 mu g . ml(-1) urine in al l individuals. It is concluded that caffeine is an ergogenic aid that stimulates endurance performance. A dose-response relation between caf feine and endurance time was not found for the dose-range investigated . The stimulating effect of caffeine was already apparent at the lowes t dose of caffeine given (5 mg . kg(-1)). At this dose urinary caffein e concentration remained below the doping limit in all subjects.