Effect of caffeine ingestion on one-repetition maximum muscular strength

Multiple studies corroborate the ergogenic properties of caffeine (CAF) for endurance performance, yet fewer investigations document the efficacy of acute caffeine intake for intense, short-term exercise. The aim of the study was to determine the ergogenic potential of caffeine during testing of muscular strength and endurance. Twenty-two resistance-trained men ingested CAF (6 mg/kg) or placebo (PL) 1 h pre-exercise in a randomized, double-blind crossover design. They refrained from caffeine intake and strenuous exercise 48 and 24 h, respectively, pre-visit. Initially, resting heart rate and blood pressure were obtained followed by one-repetition maximum (1-RM) testing on the barbell bench press and leg press. Upon determination of 1-RM, participants completed repetitions to failure at 60%1-RM. Heart rate, blood pressure, and rating of perceived exertion (RPE) were measured after the final repetition. Compared to PL, there was no effect (P > 0.05) of caffeine on muscular strength, as 1-RM bench press (116.4 ± 23.6 kg vs. 114.9 ± 22.8 kg) and leg press (410.6 ± 92.4 kg vs. 394.8 ± 95.4 kg) were similar. Total weight lifted during the 60% 1-RM trial was 11 and 12% higher for the bench press and leg press with caffeine compared to placebo, yet did not reach significance. RPE was similar at the end of resistance exercise with CAF vs. PL. Acute caffeine intake does not significantly alter muscular strength or endurance during intense bench press or leg press exercise, yet the practical importance of the increased muscular endurance remains to be explored.