Dietary nitrate improves sprint performance and cognitive function during prolonged intermittent exercise.

It is possible that dietary nitrate (NO) supplementation may improve both physical and cognitive performance via its influence on blood flow and cellular energetics. Purpose: To investigate the effects of dietary NO supplementation on exercise performance and cognitive function during a prolonged intermittent sprint test (IST) protocol, which was designed to reflect typical work patterns during team sports. Methods: In a double-blind randomised crossover study, 16 male team-sport players received NO-rich (BR; 140 mL day; 12.8 mmol of NO), and NO-depleted (PL; 140 mL day; 0.08 mmol NO) beetroot juice for 7 days. On day 7 of supplementation, subjects completed the IST (two 40-min 'halves' of repeated 2-min blocks consisting of a 6-s 'all-out' sprint, 100-s active recovery and 20 s of rest), on a cycle ergometer during which cognitive tasks were simultaneously performed. Results: Total work done during the sprints of the IST was greater in BR (123 ± 19 kJ) compared to PL (119 ± 17 kJ; P < 0.05). Reaction time of response to the cognitive tasks in the second half of the IST was improved in BR compared to PL (BR first half: 820 ± 96 vs. second half: 817 ± 86 ms; PL first half: 824 ± 114 vs. second half: 847 ± 118 ms; P < 0.05). There was no difference in response accuracy. Conclusions: These findings suggest that dietary NO enhances repeated sprint performance and may attenuate the decline in cognitive function (and specifically reaction time) that may occur during prolonged intermittent exercise. [ABSTRACT FROM AUTHOR]