AUTHOR=Moreno Berta , Morencos Esther , Vicente-Campos Davinia , Muñoz Alejandro , González-García Jaime , Veiga Santiago 

TITLE=Effects of beetroot juice intake on repeated performance of competitive swimmers

JOURNAL=Frontiers in Physiology

VOLUME=13

YEAR=2023

URL=https://www.frontiersin.org/journals/physiology/articles/10.3389/fphys.2022.1076295

DOI=10.3389/fphys.2022.1076295

ISSN=1664-042X

ABSTRACT=<p><bold>Background:</bold> Beetroot juice is a sport supplement with a high level of evidence on the physical performance enhancement. However, in swimming, there is no clear data about the effects of beetroot juice on performance.</p><p><bold>Objective:</bold> To investigate whether an acute intake of beetroot juice (BJ) improves the performance of competitive swimmers in a repeated maximum swimming effort.</p><p><bold>Method:</bold> Thirteen national-level swimmers (six females and seven males), participated in this randomized, double-blind crossover study. In two different trials, swimmers ingested a 70-mL placebo shot (.04 mmol NO<sub>3</sub><sup>−</sup>; PLA) or a 70-mL Beet-It shot (6.4 mmol of NO<sub>3</sub><sup>−</sup>beet juice [BJ]) 3 h before undergoing a 6 × 100-m front-crawl maximal effort test with 7 min rest between each 100 m.</p><p><bold>Results:</bold> Overall, 100-m times showed no difference between the BJ and PLA groups (<italic>p</italic> = .364), although a possibly shorter time was observed for BJ in the last repetition (<italic>p</italic> = .104; mean difference [MD] = −.99 s, mean-based inference [MBI] = 49/51/0). Participants in the BJ condition showed a possibly lower rate of perceived exertion in the first (<italic>p</italic> = .242, MD = −.85, MBI = 70/28/2) and second repetitions (<italic>p</italic> = .165, MD = 1.15, MBI = 83/16/1), whereas Total Quality Recovery scale scores were likely higher in the first (<italic>p</italic> = .110, MD = 1.15, MBI = 83/16/1) and third (<italic>p</italic> = .082, MD = −.77, MBI = 70/29/1) repetitions compared with those in the PLA group. Blood lactate concentration [La<sup>+</sup>] levels showed no differences between groups in any of the repetitions (<italic>p</italic> &gt; .05, unclear), and we observed an increase in 100-m times for both BJ and PLA (BJ: <italic>p</italic> = .014, MD = −1.51 s; PLA: <italic>p</italic> = .029, MD = −1.57 s) after the fifth repetition.</p><p><bold>Conclusion:</bold> No clear differences in performance were observed in a 6 × 100-m repeated sprint test by competitive swimmers when supplementing (or not) with BJ. However, there was a trend toward a better recovery between efforts and a better tolerance of fatigue when swimmers ingested BJ.</p>