Effect of beetroot juice supplementation on the result obtained in a maximum incremental test and in two lower body power assessment tests in amateur triathletes

Abstract

The aim was to analyze the effects of beetroot juice supplementation (BJ) on sports performance in amateur triathletes, measured using a bilateral and unilateral half squat protocol, and a contramovement jump (CMJ), fatigue situation. Twelve amateur triathletes participated in this randomized, double-blind, crossover design consisting of two evaluation sessions consisting of an incremental test until exhaustion performed between two CMJs and two half-squat tests with 30 and 40 kg. bilateral and unilateral loading. The nutritional intervention consisted of taking 140 mL of BJ or placebo 2.5 h before the test. BJ supplementation improved absolute (p = 0,033) and relative (p = 0,011) oxygen uptake (VO2max) in incremental test in comparison to placebo. (4,12 ± 0,70 vs. 3,72 ± 0,90 ml·kg-1·min-1 and 54,82 ± 7,72 vs. 44,48 ± 15,84 ml·kg-1·min-1). On the other side, no significant interaction (p > 0,05, n2p = 0,03-0,30) was found for any of the variables studied in relation to bilateral and unilateral performance in half squat or CMJ between the condition (placebo and BJ) and time (before, PRE and after, POST). These results show that supplementation with BJ helps to exhibit greater VO2max in amateur triathletes but does not reduce fatigue compared to the placebo condition.