Effects of Acute Yohimbine Hydrochloride Ingestion on Bench Press Performance in Resistance-Trained Males

Abstract

Yohimbine hydrochloride (YHM) is an alpha-2-adrenergic receptor antagonist that possesses sympathomimetic properties, but few studies have investigated YHM in the context of exercise. The purpose of this study was to examine the effects of acute YHM ingestion on bench press exercise power, velocity, and strength-endurance levels. In a double-blinded crossover design, resistance-trained males (n = 16) participated in two separate bench press trials, each with a different single-dose treatment: placebo (PL; gluten-free corn starch) or yohimbine hydrochloride (YHM; 2.5 mg). In each trial, the participants consumed their respective treatment 20 min prior to exercise. Following a warm-up, the participants completed 1 set × 2 explosive repetitions while a linear position transducer monitored the barbell velocity. The participants then completed 3 sets × repetitions to failure (RTF) at 75% of 1-repetition maximum (1-RM) separated by 2 min of rest. The motivation to exercise and subjective measures of energy or fatigue were measured post-exercise. The total RTF, mean velocity, mean power, motivation, and subjective energy or fatigue values were compared and analyzed. The mean power (p = 0.472; d = 0.16) and mean velocity (p = 0.297; d = 0.25) values were unchanged by treatment. However, the RTF (p = 0.002; d = 0.82) value was higher with YHM treatment. The motivation to exercise (p = 0.011; d = 0.64) and energy levels (p < 0.001; d = 1.27) were significantly higher with YHM ingestion versus PL. The subjective fatigue was significantly lower with YHM ingestion (p < 0.001; d = 1.65). In conclusion, the current findings show that YHM consumption enhanced muscular strength-endurance while improving feelings of motivation, energy, and fatigue. YHM ingestion may, therefore, be useful for athletes or competitors seeking to improve their performance or combat subjective fatigue.