Effects of acute beetroot juice intake on performance, maximal oxygen uptake, and ventilatory efficiency in well-trained master rowers: a randomized, double-blinded crossover study

Abstract

Background: Beetroot juice (BRJ) intake has been considered a practical nutritional strategy among well-trained athletes. This study aimed to assess the effects of BRJ intake on performance, cardiorespiratory and metabolic variables during a simulated 2000-meter rowing ergometer test in well-trained master rowers.

Method: Ten well-trained male master rowers (30-48 years) participated in a randomized, double-blind, crossover design for 3 weeks. In the first week, a researcher explained all the experimental procedures to the participants. In the next two weeks, the participants were tested in 2 rowing ergometer sessions, separated from each other by a 7-day washout period. In both strictly identical sessions, the participants randomly drank BRJ or placebo (PL) 3 hours before the start of the tests. Subsequently, the participants carried out the 2000-meter rowing ergometer tests. Oxygen saturation and blood lactate measurements were performed before starting (pretest) and at the end of the test (posttest). Performance parameters and cardiorespiratory variables were recorded during the rowing ergometer test.

Results: An improvement in time trial performance was observed, with a mean difference of 4 seconds (90% confidence limits ± 3.10; p ≤ 0.05) compared to PL. Relative and absolute $\mathrm{maximaloxygenuptake}\left(\dot{V}{O}_{2max}\right)$ increased (mean difference of 2.10 mL·kg^-1·min^-1, 90% confidence limits ± 1.80; mean difference of 0.16 L·min^-1 90% confidence limits ± 0.11, respectively; p ≤ 0.05) compared to PL. No ergogenic effect was observed on ventilatory efficiency and blood lactate concentrations after BRJ intake.

Conclusion: Acute BRJ intake may improve time trial performance as well as $\dot{V}{O}_{2max}$ in well-trained master rowers. However, BRJ does not appear to improve ventilatory efficiency.

Keywords: Nitrate supplementation; cardiorespiratory performance; lactate; nitric oxide; rowing ergometer; time trial performance.

Figure 1.

CONSORT flowchart of randomized, double-blind, crossover design.

Figure 2.

Experimental procedure of the rowing ergometer test.

Figure 3.

Differences between the experimental conditions and individual response of each participant: (a) time trial. (b) Relative maximal oxygen uptake ($\dot{V}{\mathrm{O}}_{2max}$).