Effect Of Standardized Encapsulated Caffeine On Cardiovascular, Metabolic, And Perceptual Responses During Steady State Exercise In Average College-Age Men

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PURPOSE: Due to easy accessibility, caffeine is a highly used ergogenic aid. Many studies have investigated the ingestion of caffeine as a dosage relative to body mass, but fewer investigations have featured absolute dosages of caffeine. The purpose of this study was to examine the effect of an absolute dose of caffeine on heart rate (HR), oxygen uptake (VO2), and rating of perceived exertion (RPE) during exercise. METHODS: A double blind crossover design was implemented for this study. Five men completed a pretest session to measure maximal oxygen uptake (VO2max). Then on two separate experimental trials, subjects ingested either 600 mg of encapsulated caffeine (CAF) or placebo (PLA), rested for one hour, then exercised on a cycle ergometer at 50% VO2max for 45 min. Measurements were recorded at rest, 15 min, 30 min, and 45 min during each trial. RESULTS: A treatment × time interaction approached significance (p=0.07), suggesting lower HR during PLA trials compared to CAF trials. VO2 increased (p < 0.001) from rest then remained steady during exercise but was not different between treatments (p=0.69 for interaction). RPE increased (p < 0.001) from rest then remained steady during exercise but was not different between treatments (p=0.65 for interaction). CONCLUSIONS: These preliminary results suggest that caffeine ingestion might result in elevated heart rate without decreasing ratings of perceived exertion during exercise. However, these are preliminary results on college-age men with average level fitness. Future studies should investigate this effect among different fitness levels and sexes.