Effects of a Short-Term High-Nitrate Diet on Exercise Performance

Abstract

It has been reported that nitrate supplementation can improve exercise performance. Most of the studies have used either beetroot juice or sodium nitrate as a supplement; there is lack of data on the potential ergogenic benefits of an increased dietary nitrate intake from a diet based on fruits and vegetables. Our aim was to assess whether a high-nitrate diet increases nitric oxide bioavailability and to evaluate the effects of this nutritional intervention on exercise performance. Seven healthy male subjects participated in a randomized cross-over study. They were tested before and after 6 days of a high (HND) or control (CD) nitrate diet (~8.2 mmol∙day−1 or ~2.9 mmol∙day−1, respectively). Plasma nitrate and nitrite concentrations were significantly higher in HND (127 ± 64 µM and 350 ± 120 nM, respectively) compared to CD (23 ± 10 µM and 240 ± 100 nM, respectively). In HND (vs. CD) were observed: (a) a significant reduction of oxygen consumption during moderate-intensity constant work-rate cycling exercise (1.178 ± 0.141 vs. 1.269 ± 0.136 L·min−1); (b) a significantly higher total muscle work during fatiguing, intermittent sub-maximal isometric knee extension (357.3 ± 176.1 vs. 253.6 ± 149.0 Nm·s·kg−1); (c) an improved performance in Repeated Sprint Ability test. These findings suggest that a high-nitrate diet could be a feasible and effective strategy to improve exercise performance.

Ergogenic effects of beetroot juice supplementation during severe-intensity exercise in obese adolescents

“…Interestingly, in BR the time to exhaustion did not improve in 3 of 10 subjects, whereas it was remarkably higher in 5 of 10 subjects. This heterogeneity of results has been already reported by other authors both in healthy subjects (28) and in patients (43), and it has been shown to be correlated with changes of plasma [NO 3 Ϫ ] or [NO 2 Ϫ ] after supplementation. In our subjects, we did not observe any correlation between time to exhaustion and plasma [NO 3 Ϫ ].…”

“…Although relatively small, this amount could become a problem during long-term supplementation in the obese population. Future studies should therefore consider other sources of NO 3 Ϫ for chronic supplementations, such as nitrate-rich vegetables, as previously utilized in healthy subjects (28).…”

Beetroot juice ingestion during prolonged moderate-intensity exercise attenuates progressive rise in O2 uptake

“…Ϫ supplementation can enhance short-duration (Ͻ30 min) exercise performance (1,2,11,35,48). However, the efficacy of NO 3 Ϫ supplementation in improving longer duration exercise performance is less clear (6,11,12,34,57).…”

Beetroot juice versus chard gel: A pharmacokinetic and pharmacodynamic comparison of nitrate bioavailability

“…delivery, including simple sodium (28) or potassium salts (23), NO 3 --rich foods (44), 68 concentrated beetroot juice (BR) (58), and chard gel (GEL) (37,38 from the first blood sample until the 3.5 h sample, after which they were allowed to 151 sit at a desk, returning 30 min before the final sample. During the experimental trials,…”