Dietary nitrate supplementation improves sprint and high-intensity intermittent running performance

The influence of dietary nitrate (NO3-) supplementation on indices of maximal sprint and intermittent exercise performance is unclear. Purpose: To investigate the effects of NO3- supplementation on sprint running performance, and cognitive function and exercise performance during the sport-specific Yo-Yo Intermittent Recovery level 1 test (IR1). Methods: In a double-blind, randomized, crossover study, 36 male team-sport players received NOS-rich (BR; 70 mL.day(-1); 6.4 mmol of NO3-), and NO3--depleted (PL; 70 day(-1); 0.04 mmol NO3-) beetroot juice for 5 days. On day 5 of supplementation, subjects completed a series of maximal 20-m sprints followed by the Yo-Yo IR1. Cognitive tasks were completed prior to, during and immediately following the Yo-Yo IR1. Results: BR improved sprint split times relative to PL at 20 m (1.2%; BR 3.98 +/- 0.18 vs. PL 4.03 +/- 0.19 s; P < 0.05), 10 m (1.6%; BR 2.53 +/- 0.12 vs. PL 2.57 +/- 0.19 s; P < 0.05) and 5 m (2.3%; BR 1.73 +/- 0.09 vs. PL 1.77 +/- 0.09 s; P < 0.05). The distance covered in the Yo-Yo IR1 test improved by 3.9% (BR 1422 +/- 502 vs. PL 1369 +/- 505 m; P < 0.05). The reaction time to the cognitive tasks was shorter in BR (615 +/- 98 ms) than PL (645 +/- 120 ms; P < 0.05) at rest but not during the Yo-Yo IR1. There was no difference in response accuracy. Conclusions: Dietary NOS supplementation enhances maximal sprint and high-intensity intermittent running performance in competitive team sport players. Our findings suggest that NO3- supplementation has the potential to improve performance in single-sprint or multiple-sprint (team) sports. (C) 2016 Elsevier Inc. All rights reserved.