A randomized controlled trial of nitrate supplementation in well-trained middle and older-aged adults

Purpose Nitrate (NO 3 - ), through its conversion to nitrite (NO 2 - ) and nitric oxide, has been shown to increase exercise tolerance in healthy younger adults and older diseased patients. Nitrate’s effect in well-trained middle to older-aged adults has not been studied. Therefore, the purpose of this investigation was to examine the effects of a NO 3 - rich beverage on submaximal constant work rate exercise time in well-trained middle to older-aged adults. Methods This was a randomized controlled cross-over trial with 15 well-trained middle to older-aged adults, 41–64 year-old, who received one of two treatments (NO 3 - rich beverage then placebo or placebo then NO 3 - rich beverage), after which an exercise test at 75 percent of the subject’s maximal work rate was completed. Results The NO 3 - rich beverage increased plasma NO 3 - and NO 2 - levels by 260 μM and 0.47 μM, respectively (p<0.001). Exercise time was not significantly different (p = 0.31) between the NO 3 - rich versus placebo conditions (1130±151 vs 1060±132 sec, respectively). Changes in exercise time between the two conditions ranged from a 55% improvement to a 40% decrease with the NO 3 - rich beverage. Oxygen consumption and rating of perceived exertion were not significantly different between the two conditions. Conclusion In middle to older-aged well-trained adults, NO 3 - supplementation has non-significant, albeit highly variable, effects on exercise tolerance. ClinicalTrials.gov Identifier: NCT03371966