High or low volume beetroot juice supplementation might positively affect physical capacity and isokinetic muscle function in power athletes

BACKGROUND: Beetroot juice is an ergogenic aid containing high levels of nitrate and is known to have many physiological benefits. OBJECTIVE: This study aimed to examine the effects of beetroot juice supplementation on the physical capacity and isokinetic muscle function of power athletes. METHODS: Thirteen power athletes were orally administered three different volumes of beetroot juice: placebo (70 ml), low-volume beetroot juice (70 ml), and high-volume beetroot juice (140 ml). The Harvard step test, 20 m sprint, side-step, reaction time, Wingate test, blood lactate analysis, and isokinetic knee and trunk tests were performed to confirm their physical capacity and isokinetic muscle function. Significant differences between the drink groups were determined using repeated-measures ANOVA. RESULTS: There were no significant differences in the Harvard step, side step, whole-body reaction time, anaerobic power, blood lactate concentration, and isokinetic muscular strength in the knee and trunk for all groups. However, the 20 m sprint and isokinetic muscular endurance of the knee extensor were significantly higher with beetroot juice intake. CONCLUSIONS: Our findings suggest that > 70 ml of beetroot juice supplement before performance may be useful as an ergogenic supplement to improve performance-related physical fitness, including speed and muscular endurance, in power athletes.