Effects of Beetroot Juice Ingestion on Physical Performance in Highly Competitive Tennis Players

Abstract

Beetroot juice (BJ) contains high levels of inorganic nitrate (NO3−) and its intake has good evidence in increasing blood nitrate/nitrite concentrations. The ingestion of BJ has been associated with improvements in physical performance of endurance sports, however the literature in intermittent sports is scarce. The aim of this study was to investigate whether BJ could improve physical performance in tennis players. Thirteen well-trained tennis players (25.4 ± 5.1 years) participated in the study during their preparatory period for the tennis season. Subjects were randomly divided into two groups and performed a neuromuscular test battery after either BJ or placebo (PLA) consumption. Both trials were executed on two separate days, in randomized order, with one week of wash out period. The test battery consisted of serve velocity test (SVT), countermovement jump (CMJ), isometric handgrip strength (IHS), 5-0-5 agility test (5-0-5), and 10 m sprint (10-m). No significant differences were found in SVT (1.19%; p = 0.536), CMJ (0.96%; p = 0.327), IHS (4.06%; p = 0.069), 5-0-5 dominant and nondominant side (1.11–2.02%; p = 0.071–0.191) and 10-m (1.05%; p = 0.277) when comparing BJ and PLA ingestion. Thus, our data suggest that low doses of BJ (70 mL) consumption do not enhance tennis physical performance.

Nutritional Ergogenic Aids in Racquet Sports: A Systematic Review

“…In intermittent sports such as tennis, beetroot juice containing 6.4 mmol nitrate did not show any improvements in either explosive movements (serve velocity, jump, sprint, handgrip force) or perceptual exertion in high-level tennis players [36] with a low risk of bias. These results are similar to the ones found in recent studies in which short and high-intensity movements (such as countermovement jump, isometric strength, or muscular movement concentric velocity) were evaluated after the consumption of beetroot juice containing 6.4-17.7 mmol nitrate [57][58][59].…”

“…Most of the trials assessed showed an unclear level in the criteria of selection bias, both in the randomized treatment order and in the evaluation of the carry-over effect. Only the trials by Vergauwen; 1998, [ 26 ] Lopez-Samanes; 2020 [ 36 ] and Abian; 2015 [ 40 ] suitably described the tools used for randomization treatment, while trials by Wu; 2010 [ 34 ], Yang; 2017 [ 38 ], Abian; 2015 [ 40 ] and Muller; 2019 [ 45 ] used tests to check if the washout time between conditions was suitable. Moreover, most of the studies also showed a high risk of detection bias except for trials by Gallo-Salazar; 2015 [ 30 ] and Abian; 2015 [ 40 ], which specifically indicated that blinding was kept until the statistical analysis was performed.…”

“…Three studies about NO precursors were found. The intake of 70 mL beetroot juice 3 h before the test did not show differences compared to control [ 36 ]. On the other hand, only citrulline malate supplementation (80 g 60 min before the trial) [ 37 ] or together with arginine and BCAAs (0.05 g/kg 80 min before test) [ 38 ] showed improvements compared with control.…”

“…In the case most evaluated supplement (n = 10) followed by creatine monohydrate (n nitric oxide (NO) precursors (n = 3), and hydration agents (n = 1). [36] Nutrients 2020, 12, x FOR PEER REVIEW 17 of 25 [41] [42] * [43] [44]…”

“…The RCTs of 2006 [33] and oup trials, so the criteria of random sequence generation and instead of randomized treatment order and carry-over effect ed showed an unclear level in the criteria of selection bias, both nd in the evaluation of the carry-over effect. Only the trials by es; 2020 [36] and Abian; 2015 [40] suitably described the tools hile trials by Wu; 2010 [34], Yang; 2017 [38], Abian; 2015 [40] and if the washout time between conditions was suitable. Moreover, igh risk of detection bias except for trials by Gallo-Salazar; 2015 ecifically indicated that blinding was kept until the statistical s [27,38,42,44,45] were at a high risk of performance bias due to ding.…”