Nitrate supplementation enhances exercise performance: A systematic review and meta‐analysis
Bibliographic record
Abstract
Although over 100 studies and reviews have examined the ergogenic effects of dietary nitrate (NO 3 − ) supplementation ( e.g. beetroot juice) in young, healthy men and women, it is unclear if participant and environmental factors modulate the well‐described ergogenic effects—particularly relevant factors include biological sex, aerobic fitness and fraction of inspired oxygen (F i O 2 ) during exercise. To address this limitation, the literature was systematically reviewed for randomized, cross‐over, placebo‐controlled studies reporting exercise performance outcome metrics with NO 3 − supplementation in young, healthy adults. There were 2,033 articles identified, and 80 articles met inclusion criteria for the meta‐analysis. Random‐effects meta‐analysis demonstrated that exercise performance was improved with NO 3 − supplementation compared to placebo ( d =0.174, 95% CI [0.120–0.229], P <0.001). Subgroup analyses conducted on biological sex, aerobic fitness and F i O 2 demonstrated that the ergogenic effect of NO 3 − supplementation was: 1) not observed in studies with only women ( n =6, d=0.116, 95% CI [−0.126–0.358], P =0.347), 2) not observed in participants with moderate aerobic fitness (less than 45 mL·kg −1 ·min −1 ; n =4, d =0.168, 95% CI [−0.134–0.469], P =0.276) or elite aerobic fitness (65 mL·kg −1 ·min −1 or greater; n =26, d =0.021, 95% CI [−0.103–0.144], P =0.745) and 3) was not modulated by F i O 2 (hypoxia: n =17, d =0.214, 95% CI [0.054–0.375], P =0.009 vs. normoxia n =97, d =0.175, 95% CI [0.114–0.237], P <0.001). Together, the meta‐analyses demonstrated a clear ergogenic effect of NO 3 − supplementation in recreationally‐active, young, healthy men across many different exercise paradigms and NO 3 − supplementation parameters; however, the effect size of NO 3 − supplementation was objectively small . Although NO 3 − supplementation may be effective in moderately fit, healthy men, NO 3 − supplementation has limited utility as an ergogenic aid in participants that have optimized other training parameters. Mechanistic research and studies incorporating a wide variety of subjects ( e.g. women) are needed to advance the study of NO 3 − supplementation; however, additional descriptive studies of young healthy men may have limited utility. Figure 1 Figure 2
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.007 | 0.016 |
| Meta-epidemiology (narrow) | 0.003 | 0.001 |
| Meta-epidemiology (broad) | 0.015 | 0.028 |
| Bibliometrics | 0.003 | 0.004 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.003 | 0.001 |
| Open science | 0.002 | 0.001 |
| Research integrity | 0.002 | 0.002 |
| Insufficient payload (model declined to judge) | 0.004 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".