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

Since the effect of dietary nitrate (NO) supplementation on rugby performance is unclear, the aim of the present study was to determine the effect of acute NO supplementation, on the modified Yo-Yo intermittent recovery level 1 (IR1) performance test in trained male rugby players. 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 NO-rich (BRJ; ∼12.8 mmol NO) or NO-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. Plasma NO (BRJ: 570 ± 146 µM PLA: 72 ± 23 µM) and nitrite (NO) concentrations (BRJ: 320 ± 123 nM PLA: 103 ± 57 nM) were increased after BRJ compared to PLA supplementation (both  < 0.001). Performance in the modified Yo-Yo IR1 test did not differ between BRJ (542 ± 209 m) and PLA (498 ± 185 m,  = 0.3). The jump height in pre-CMJ and in post-CMJ were similar between trials (both  > 0.05). Acute BRJ supplementation increased plasma NO and NO 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 NO supplementation as an ergogenic aid to enhance physical performance in trained male rugby players.