Effects of Beetroot Juice Supplementation on Performance and Fatigue in a 30-s All-Out Sprint Exercise: A Randomized, Double-Blind Cross-Over Study.
Nutrients. 2018 Sep 4 ;10(9). Epub 2018 Sep 4. PMID: 30181436
As a nitric oxide precursor, beetroot juice (BJ) is known to enhance high-intensity exercise performance (80⁻100% VO) yet its impacts on higher intensity sprint exercise (>100% VO) remain to be established. This study sought to examine the effects of BJ supplementation on performance and subsequent fatigue during an all-out sprint exercise. Using a randomized cross-over, double-blind, placebo-controlled design, 15 healthy resistance-trained men (22.4± 1.6 years) ingested 70 mL of either BJ or placebo. Three hours later, participants undertook a 30-s all-out Wingate test. Before and after the sprint exercise and at 30 s and 180 s post-exercise, three countermovement jumps (CMJ) were performed and blood lactate samples were obtained. Compared toplacebo, BJ consumption improved peak (placebo vs. BJ, 848 ± 134 vs. 881 ± 135 W;= 0.049) and mean (641± 91 vs. 666 ± 100 W;= 0.023) power output and also reduced the time taken to reach Win the Wingate test (8.9± 1.4 vs. 7.3 ± 0.9 s;= 0.003). No differences were detected in the fatigue index. In addition, while over time CMJ height and power diminished (ANOVA<0.001) and blood lactate levels increased (ANOVA<0.001), no supplementation effect was observed. Our findings indicate that while BJ supplementation improved performance at the 30-s cycling sprint, this improvement was not accompanied by differences in fatigue during or after this type of exercise.