Acute effects of two caffeine doses on bar velocity during the bench press exercise among women habituated to caffeine: a randomized, crossover, double-blind study involving control and placebo conditions

Abstract

The main goal of this study was to evaluate the effectiveness of two different doses of caffeine (3 and 6 mg/kg) to enhance bar velocity during the bench press in women habituated to caffeine. Twelve recreationally trained women (age: 23.3\u2009±\u20090.8 years, body mass: 60.7\u2009±\u20095.7 kg, bench press one-repetition maximum (1RM): 44.3\u2009±\u20097.8 kg, daily caffeine ingestion: 5.7\u2009±\u20092.0 mg/kg/day) participated in a randomized double-blind experimental design. Each participant performed four different experimental sessions: after no supplementation (control, CON), after ingesting 3 and 6 mg/kg of caffeine (CAF-3 and CAF-6, respectively), or after ingesting a placebo (PLAC). In each experimental session, the participants performed 3 sets of 3 repetitions of the bench press exercise at 50% 1RM. A two-way repeated-measures ANOVA with subsequent post hoc analyses indicated significant increases in peak velocity (p\u2009<\u20090.01; ES\u2009=\u20090.91) and mean velocity (p\u2009<\u20090.01; ES\u2009=\u20090.78) after the intake of CAF-6 compared to CON. The study did not show significant differences in bar velocity between CAF-6 and PLAC and between CAF-3 and PLAC. No significant differences in bar velocity were observed between CAF-3 and CAF-6 conditions. These results suggest that 6 mg/kg of caffeine can be an effective dose to improve power-specific training outcomes in women habituated to caffeine. However, the ergogenic effect of 6 mg/kg of caffeine may be derived from a combination of biological effects and expectancy, as this dose was only superior to the control condition with no differences over the placebo.