Acute Effects of Beetroot Juice Supplements on Resistance Training: A Randomized Double-Blind Crossover.

Antonio Ranchal-Sanchez,Julian Campos-Perez,Candelaria Alonso De La Florida-Villagran,Victor Manuel Diaz-Bernier,Francisco Jesus Llorente-Cantarero,Jose Manuel Jurado-Castro

doi:10.3390/nu12071912

Abstract

The ingestion of beetroot juice (BJ) has been associated with improvements in physical performance in endurance sports, however the literature on resistance training (RT) is scarce. The aim of this study was to investigate the acute effects of BJ compared to a placebo (PLA) on muscular endurance and movement concentric velocity during RT. Twelve healthy men performed an incremental RT test (back squat and bench press) with three sets, at 60%, 70%, and 80% of their repetition maximum (1-RM). Movement velocity variables, total number of repetitions performed until concentric failure, blood lactate, and ratings of perceived effort post-training were measured. A higher number of repetitions were recorded with BJ compared to those with PLA (13.8 ± 14.4; p < 0.01; effect size (ES) = 0.6). Differences were found at 60% 1-RM (9 ± 10; p < 0.05; ES = 0.61) and 70% 1-RM (3.1 ± 4.8; p < 0.05; ES = 0.49), however, no differences were found at 80% 1-RM (1.7 ± 1; p = 0.12; ES = 0.41). A greater number of repetitions was performed in back squat (13.4 ± 13; p < 0.01; ES = 0.77), but no differences were observed in bench press (0.4 ± 5.1; p = 0.785; ES = 0.03). No differences were found for the rest of the variables (p > 0.05). Acute supplementation of BJ improved muscular endurance performance in RT.

Highlights

Sports supplements based on beetroot juice (BJ) have been studied recently, with a great deal of interest shown by the field of sports nutrition, as well as sports performance [1], and a focus on the effects on reducing cardiovascular diseases and coronary heart disease [1,2]
There was an increase in the total number of repetitions on the day BJ was consumed compared to the day the PLA was taken (MD: 13.8 ± 14.4; p < 0.01; effect size (ES) = 0.6), in addition, according to the variable intensities in the exercise protocol, differences were found for 60% 1-RM (MD: 9 ± 10; p < 0.05; ES = 0.61), 70% 1-RM (MD: 3.1 ± 4.8; p < 0.05; ES = 0.49), but no differences were found for 80% 1-RM (MD: 1.7 ± 1; p = 0.12; ES = 0.41) (Figure 2A)
Differences were found in the total repetitions of the back squat exercise (MD: 13.4 ± 13; p < 0.01; ES = 0.77), both at 60% 1-RM (MD: 8.7 ± 3.3; p < 0.01; ES = 0.78) and at 70% 1-RM (MD: 3.1 ± 2.5; p < 0.05; ES = 0.59), no differences were obtained at 80% 1-RM in favor of BJ (MD: 1.6 ± 0.9; p = 0.100; ES = 0.44) (Figure 2B)

Summary

Introduction

Sports supplements based on beetroot juice (BJ) have been studied recently, with a great deal of interest shown by the field of sports nutrition, as well as sports performance [1], and a focus on the effects on reducing cardiovascular diseases and coronary heart disease [1,2]. This process is due to the action of nitrate reductase facultative anaerobic bacteria present at the dorsal surface of the tongue [3] This causes an increase in NO2 levels in the stomach, where NO2 is decomposed into nitric oxide (NO) and gets into the systemic circulation [4,5]. It has been shown that the intake of NO3 − produces an enhancement of economy, reducing oxygen consumption (VO2 ) during exercise [1], which may indicate an improvement in adenosine triphosphate (ATP) synthesis due to a reduction of VO2 cost [11] Thanks to these benefits of BJ supplements, BJ consumption and its effects have been widely evaluated and constated in endurance sports as athletics, cycling, time trials, and rowing, where the cardiovascular system has an important role for sport performance [1,6,12]

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