The effect of dietary nitrate supplementation on endurance exercise performance in healthy adults: A systematic review and meta-analysis
McMahon, Nicholas F., Leveritt, Michael D., & Pavey, Toby G. (2016) The effect of dietary nitrate supplementation on endurance exercise performance in healthy adults: A systematic review and meta-analysis. Sports Medicine. (In Press)
Recent research into the use of dietary nitrates and their role in vascular function has led to it becoming progressively more popular amongst athletes attempting to enhance performance.
The objective of this review was to perform a systematic review and meta-analysis of the literature to evaluate the effect of dietary nitrate (NO3 −) supplementation on endurance exercise performance. An additional aim was to determine whether the performance outcomes are affected by potential moderator variables.
Relevant databases such as Cochrane Library, Embase, PubMed, Ovid, Scopus and Web of Science were searched for the following search terms ‘nitrates OR nitrate OR beetroot OR table beet OR garden beet OR red beet AND exercise AND performance’ from inception to October 2015.
Studies were included if a placebo versus dietary nitrate-only supplementation protocol was able to be compared, and if a quantifiable measure of exercise performance was ≥30 s (for a single bout of exercise or the combined total for multiple bouts).
Study appraisal and synthesis
The literature search identified 1038 studies, with 47 (76 trials) meeting the inclusion criteria. Data from the 76 trials were extracted for inclusion in the meta-analysis. A fixed-effects meta-analysis was conducted for time trial (TT) (n = 28), time to exhaustion (TTE) (n = 22) and graded-exercise test (GXT) (n = 8) protocols. Univariate meta-regression was used to assess potential moderator variables (exercise type, dose duration, NO3 − type, study quality, fitness level and percentage nitrite change).
Pooled analysis identified a trivial but non-significant effect in favour of dietary NO3 − supplementation [effect size (ES) = −0.10, 95 % Cl = −0.27 to 0.06, p > 0.05]. TTE trials had a small to moderate statistically significant effect in favour of dietary NO3 − supplementation (ES = 0.33, 95 % Cl = 0.15–0.50, p < 0.01). GXT trials had a small but non-significant effect in favour of dietary NO3 − supplementation in GXT performance measures (ES = 0.25, 95 % Cl = −0.06 to 0.56, p > 0.05). No significant heterogeneity was detected in the meta-analysis. No statistically significant effects were observed from the meta-regression analysis.
Dietary NO3 − supplementation is likely to elicit a positive outcome when testing endurance exercise capacity, whereas dietary NO3 − supplementation is less likely to be effective for time-trial performance. Further work is needed to understand the optimal dosing strategies, which population is most likely to benefit, and under which conditions dietary nitrates are likely to be most effective for performance.
Impact and interest:
Citation counts are sourced monthly from and citation databases.
These databases contain citations from different subsets of available publications and different time periods and thus the citation count from each is usually different. Some works are not in either database and no count is displayed. Scopus includes citations from articles published in 1996 onwards, and Web of Science® generally from 1980 onwards.
Citations counts from theindexing service can be viewed at the linked Google Scholar™ search.
|Item Type:||Journal Article|
|Divisions:||Current > QUT Faculties and Divisions > Faculty of Health
Current > Institutes > Institute of Health and Biomedical Innovation
Current > Schools > School of Exercise & Nutrition Sciences
|Copyright Owner:||Copyright 2016 Springer International Publishing Switzerland|
|Deposited On:||07 Sep 2016 22:45|
|Last Modified:||09 Sep 2016 00:11|
Repository Staff Only: item control page