The Effects of Beetroot Juice Supplementation on Performance and Fatigue During Single and Repeated Sprints: A...

Background/Objectives: Beetroot juice (BRJ), a dietary nitrate source, may enhance high-intensity intermittent exercise, but its effects on single- and repeated-sprint performance remain unclear. This systematic review and meta-analysis aimed to evaluate the effects of BRJ supplementation on sprint-related performance and neuromuscular, perceptual, and physiological outcomes. Methods: PubMed, Scopus, and Web of Science were searched for trials published from 2014 to June 2026. Eligible studies compared BRJ with placebo or control in healthy adults aged 18-40 years. The review followed PRISMA guidelines. Methodological quality and risk of bias were assessed using the PEDro scale and Cochrane RoB 2 tool. Evidence certainty was assessed using GRADE. Standardized mean differences (SMDs) with 95% confidence intervals (CIs) were calculated. Results: Twenty-three randomized trials involving 401 participants were included, and 21 contributed to the meta-analysis. BRJ improved time to peak power in four Wingate-based studies (SMD = -0.92, 95% CI: -1.29 to -0.54, p < 0.001) and handgrip strength (SMD = 0.40, 95% CI: 0.05 to 0.74, p = 0.027). No significant effects were observed for countermovement jump, peak or mean power, 10 m or 20 m sprint performance, perceived exertion, heart rate, or blood lactate. Sex did not significantly moderate the effects, although female data were limited. Certainty was low for most outcomes and very low for 20 m sprint performance and blood lactate. Conclusions: BRJ may improve time to peak power and handgrip strength; however, low- to very-low-certainty evidence does not support its routine use to enhance short-distance or repeated-sprint performance.