Randell, R., Hodgson, A. B., & Jeukendrup, A. E. (2012). The metabolic and performance effects of caffeine compared to coffee during exercise. Presentation 2781 at the 59th Annual Meeting of the American College of Sports Medicine, San Francisco, California; May 29-June 2, 2012.

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This study investigated the metabolic effects of pre-exercise ingested caffeine and coffee during moderate intensity exercise and compared their performance-enhancing effects. Trained male cyclists/triathletes (N = 8) completed 30 minutes of steady-state cycling at approximately 55% VO2max followed by a time-trial lasting approximately 45 minutes. One hour prior to exercise each athlete consumed drinks consisting of caffeine (5mg/kg), instant coffee (5mg/kg), instant decaf coffee, or placebo.

The set workloads produced similar relative exercise intensities during steady state cycling for the four treatments. There was no observed difference in carbohydrate or fat oxidation during steady state for any of the ingested supplements. Performance times during the time-trial were significantly faster (~4.0%) and similar for both caffeine and coffee when compared to placebo and decaf coffee. Average power for the caffeine and coffee treatments during the time-trial was significantly greater when compared to placebo and decaf. No significant differences were observed between placebo and decaf during the time-trial.

Implication. Both caffeine (5mg/kg) and coffee (5mg/kg) consumed one hour before exercise can improve endurance exercise performance. Those improvements cannot be attributed to alterations in substrate metabolism as no change in fat oxidation was observed during stead state exercise.

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