Effects of Acute Yohimbine Hydrochloride Supplementation on Repeated Supramaximal Sprint Performance

Abstract

The purpose of this study was to examine the effects of a single acute dose of yohimbine hydrochloride on repeated anaerobic sprint ability. Physically active females (n = 18) completed two separate repeated supramaximal sprint trials each with a different single-dose treatment: placebo (PL; gluten-free corn starch) or yohimbine hydrochloride (YHM; 2.5 mg). For each trial, participants consumed their respective treatment 20 min before exercise. Following a warm-up, participants completed 3 × 15 s Wingate anaerobic tests (WAnTs) separated by 2 min of active recovery. A capillary blood sample was obtained pre- and immediately post-exercise to measure blood concentrations of lactate (LA), epinephrine (EPI), and norepinephrine (NE). Heart rate (HR) and rate of perceived exertion (RPE) were measured following each WAnT. Findings showed that mean power (p < 0.001; η² = 0.024), total work (p < 0.001; η² = 0.061), and HR (p < 0.001; η² = 0.046), were significantly higher with YHM supplementation versus PL. Fatigue index (p < 0.001; η² = 0.054) and post-exercise LA (p < 0.001; d = 1.26) were significantly lower with YHM compared to PL. YHM resulted in significantly higher EPI concentrations versus PL (p < 0.001; η² = 0.225) pre- and post-exercise while NE only increased as a function of time (p < 0.001; η² = 0.227) and was unaffected by treatment. While RPE increased after each WAnT, no differences between treatments were observed (p = 0.539; η² < 0.001). Together, these results suggest that acute YHM ingestion imparts ergogenic benefits which may be mediated by lower blood LA and fatigue concomitantly occurring with blood EPI increases. Thus, YHM may improve sprint performance although more mechanistic study is warranted to accentuate underlying processes mediating performance enhancement.

Keywords: Wingate; epinephrine; lactate; norepinephrine; power output.

Figure 1

(a) Mean power (watts), (b) peak power (watts), (c) total work (joules), and (d) fatigue index (watts/s) compared between placebo (PL; grey bars) and yohimbine (YHM; green bars). Data are shown as the mean ± SD. Measurements are shown for WAnT1, WAnT2, WAnT3, and the average of all three tests together (AVG) for each condition. * indicates significantly different from WAnT1 (p < 0.05). † indicates significantly different from PL (p < 0.05).

Figure 2

(a) Heart rate (HR; bpm) and (b) rate of perceived exertion (RPE; 1–10) compared between placebo (PL; grey bars) and yohimbine (YHM; green bars). Data are shown as the mean ± SD. Measurements are shown for WAnT1, WAnT2, WAnT3, and the average of all three tests together (AVG) for each condition. * indicates significantly different from WAnT1 (p < 0.05). # indicates significantly different from WAnT2 (p < 0.05). † indicates significantly different from PL (p < 0.05).

Figure 3

(a) Blood lactate (LA; mmol·L⁻¹), (b) plasma epinephrine (EPI; pg·mL⁻¹), and (c) plasma norepinephrine (NE; pg·mL⁻¹), compared between placebo (PL; grey bars) and yohimbine HCL (YHM; green bars). Measurements were also taken and compared immediately prior to (pre-) and after (post-) exercise. † indicates significantly different from PL (p < 0.05). ‡ indicates significantly different from pre-exercise (p < 0.05).