Effects of caffeine on repetitions to failure and ratings of perceived exertion during resistance training.

CONTEXT Ergogenic effects of caffeine on aerobic or endurance exercise are well documented. Conversely, the ergogenic value of caffeine on high-intensity, primarily anaerobic performance is not well understood even though the proposed mechanisms of action for caffeine permit a strong theoretical basis for application to this type of exercise. PURPOSE This study examined effects of caffeine (Ca) on number repetitions (reps), ratings of perceived exertion (RPE), and peak heart rate (PHR) during resistance-training exercise with reps performed to volitional failure. METHODS Subjects (N = 17) were tested for 10-rep maximum in bench press (BP) and leg press (LP). In sessions 2 and 3, Ca (approximately 6 mg/kg) or placebo (Pl) was ingested 1 hr beforehand in a double-blind manner and counterbalanced order. Subjects performed 3 sets to failure (BP and LP) with reps, PHR, and RPE recorded each set. Repeated-measures ANOVAs, 2 (trial) x 3 (set), were used to analyze dependent measures with the Tukey honestly significant difference used when necessary as the post hoc test. RESULTS In BP, no significant differences (Ca vs Pl) were observed (reps, RPE, PHR). During set 3 of LP training, Ca was associated with significantly higher reps (12.5 +/- 4.2 vs 9.9 +/- 2.6) and PHR (158.5 +/- 11.9 vs 151.8 +/- 13.2). No significant RPE differences were found during LP. CONCLUSIONS The findings of similar RPE concurrent with higher reps suggest that caffeine can blunt pain responses, possibly delaying fatigue in high-intensity resistance training. Ergogenic effects might be limited to the later sets in a resistance-training session. Further research is warranted regarding ergogenic effects of caffeine during resistance training and potential mechanisms of action.