Acute beetroot juice supplementation did not enhance intermittent running performance in trained rugby players

ABSTRACTPurpose: Since the effect of dietary nitrate (NO₃^-) supplementation on rugby performance is unclear, the aim of the present study was to determine the effect of acute NO₃^- supplementation, on the modified Yo-Yo intermittent recovery level 1 (IR1) performance test in trained male rugby players.Methods: In a randomised, counterbalanced, double-blind, placebo-controlled crossover design, 12 trained rugby union players performed two experimental trials three hours after supplementation of either 140 mL NO₃^--rich (BRJ; ∼12.8 mmol NO₃^-) or NO₃^--depleted (PLA) BRJ. After blood sampling, players performed the modified Yo-Yo IR1 test. Countermovement jumps (CMJ) were also measured before (pre-CMJ) and after (post-CMJ) the prone Yo-Yo IR1 test.Results: Plasma NO₃^- (BRJ: 570 ± 146 µM vs. PLA: 72 ± 23 µM) and nitrite (NO₂^-) concentrations (BRJ: 320 ± 123 nM vs. PLA: 103 ± 57 nM) were increased after BRJ compared to PLA supplementation (both P < 0.001). Performance in the modified Yo-Yo IR1 test did not differ between BRJ (542 ± 209 m) and PLA (498 ± 185 m, P = 0.3). The jump height in pre-CMJ and in post-CMJ were similar between trials (both P > 0.05).Conclusions: Acute BRJ supplementation increased plasma NO₃^- and NO₂^- concentrations but had no benefit on an intermittent running test that reflects the demands of rugby performance, and CMJ performances. The findings do not support acute high-dose NO₃^- supplementation as an ergogenic aid to enhance physical performance in trained male rugby players.