The impact of beetroot juice intake on muscle oxygenation and performance during rhythmic handgrip exercise


Background: Despite studies investigating the effect of beetroot juice (BJ) ingestion on exercise performance in several modes of exercise, it is important to evaluate how untrained subjects respond to BJ intake during fatiguing resistance exercise. Therefore, the present study investigated the effect of BJ consumption on muscle oxygenation parameters during rhythmic handgrip exercise and exercise recovery in untrained subjects. Furthermore, exercise tolerance was also evaluated. Methods: In a randomized, double-blind, crossover fashion, thirteen healthy young subjects ingested a single dose of BJ or placebo (PLA). At 150 minutes after BJ or PLA intake, participants performed 1 bout of rhythmic handgrip exercise until fatigue and muscle oxygenation parameters were continuously monitored during exercise and exercise recovery. Results: During exercise, no significant difference in deoxygenated hemoglobin and total hemoglobin were observed after supplementation. However, a significantly faster muscle oxygen saturation during exercise recovery was observed after BJ ingestion as compared to PLA without significant changes in total hemoglobin. No significant difference in exercise tolerance after supplementation was observed. Conclusion: a single dose of BJ improves muscle reoxygenation during the recovery period of rhythmic handgrip exercise in untrained subjects, despite no changes in oxygen extraction, blood volume, and exercise tolerance.