Abstract It is possible that dietary nitrate (NO3 -) supplementation may improve both physical and cognitive performance via its influence on blood flow and cellular energetics. Purpose To investigate the effects of dietary NO3 - 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 NO3 --rich (BR; 140 mL day-1; 12.8 mmol of NO3 -), and NO3 --depleted (PL; 140 mL day-1; 0.08 mmol NO3 -) 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 NO3 - enhances repeated sprint performance and may attenuate the decline in cognitive function (and specifically reaction time) that may occur during prolonged intermittent exercise.
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