Abstract P120: Acute Dietary Nitrate Supplementation Does Not Attenuate Oxidative Stress or the Hemodynamic Response During Submaximal Exercise in Hypobaric Hypoxia
Bibliographic record
Abstract
Introduction: Oxidative stress is exacerbated during hypoxic conditions (i.e. high altitude exposure, congestive heart failure, or peripheral artery disease). Dietary nitrate supplementation increases plasma nitrite (denotes nitric oxide bioavailability), reduces resting/submaximal blood pressure (BP) and may enhance exercise performance in certain healthy and diseased populations. Hypothesis: We hypothesized dietary nitrate would improve arterial oxygen saturation (SaO 2 ) and reduce: oxidative stress while reducing submaximal oxygen consumption, BP, and perceived exertion (RPE) during exercise in hypobaric hypoxia (3500m). Methods: Nine well-trained (60.0±7.0 ml/kg/min) males (29±7 yr) completed a maximal aerobic capacity test (VO 2max ) and five 5-min cycling bouts of increasing intensity at their normobaric elevation (1600m). Intensities at 25, 40, 50, 60, 70% VO 2max were used during trial 2 (T2) and trial 3 (T3) cycling bouts. Participants minimized nitrate-rich food consumption during a 4-day dietary washout prior to T2 and T3. Participants consumed a nitrate-depleted placebo (PL) or nitrate-rich (12.8 mmol; NR) beverage 2.5 hours prior to T2 and T3 in a double-blind, placebo-controlled, crossover study. Exercise during hypobaric hypoxia (3500m; T2 and T3) consisted of a 5-min warm-up (25% of normobaric VO 2max ) and four (40, 50, 60, 70% of normobaric VO 2max ) additional 5-min cycling bouts each separated by a 4-min passive rest. Results: Pre-exercise plasma nitrite was elevated following NR consumption compared to PL (p<0.05). Beverage-specific oxygen consumption, SaO 2 , BP and RPE were similar at all submaximal intensities. In both conditions (PL and NR), following exercise at 3500m, markers of oxidative stress (catalase and 8-isoprostane) were elevated compared to baseline resting values (p<0.05). However, post-exercise oxidative stress markers were similar between groups (placebo vs nitrate rich) for both catalase and 8-isoprostane (p=.94 and p=.16; respectively). Conclusions: Our findings do not support the efficacy of dietary nitrate supplementation prior to exercise at altitude in a healthy population.
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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 | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.005 | 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".