An acute dose of inorganic dietary nitrate does not improve high-intensity, intermittent exercise performance in temperate or hot and humid conditions.
PURPOSE
Dietary nitrate (NO3-) has repeatedly been shown to improve endurance and intermittent, high-intensity events in temperate conditions. However, the ergogenic effects of dietary NO3- on intermittent exercise performance in hot conditions have yet to be investigated.


METHODS
In a randomised, counterbalanced, double-blind crossover study, 12 recreationally trained males ingested a nitrate-rich beetroot juice shot (BRJ) (6.2 mmol NO3-) or a nitrate-depleted placebo (PLA) (< 0.004 mmol NO3-) 3 h prior to an intermittent sprint test (IST) in temperate (22 °C, 35% RH) and hot conditions (30 °C, 70% RH). The cycle ergometer IST consisted of twenty maximal 6 s sprints interspersed by 114 s of active recovery. Work done, power output, heart rate and RPE were measured throughout; tympanic temperature was measured prior to and upon completion.


RESULTS
There were no significant effects of supplement on sprint performance in either temperate or hot, humid conditions (p > 0.05). There was a reduced peak (BRJ: 659 ± 100W vs. PLA: 693 ± 139W; p = 0.056) and mean power (BRJ: 543 ± 29W vs. PLA: 575 ± 38W; p = 0.081) following BRJ compared to PLA in the hot and humid condition, but this was not statistically significant. There was no effect of supplement on total work done irrespective of environmental condition. However, ~ 75% of participants experienced performance decreases following BRJ in the hot and humid environment. No differences were observed between trials for tympanic temperature measured at the conclusion of the exercise trial.


CONCLUSION
In conclusion, an acute dose of inorganic dietary NO3- does not improve repeated-sprint performance in either temperate, or hot and humid conditions.
['Smith|Kieran|K|', 'Muggeridge|David J|DJ|', 'Easton|Chris|C|', 'Ross|Mark D|MD|http://orcid.org/0000-0002-0204-3915']
D000328:Adult D054874:Athletic Performance D018592:Cross-Over Studies D019587:Dietary Supplements D015444:Exercise D000067030:Fruit and Vegetable Juices D006339:Heart Rate D006358:Hot Temperature D006801:Humans D008297:Male D009566:Nitrates D012420:Running D055815:Young Adult
Nitrate High-intensity Exercise Humidity Beetroot juice Heat