Effects of Dietary Nitrate Supplementation on Physiological Responses, Cognitive Function, and Exercise Performance at Moderate and Very-High Simulated Altitude

Study answer

What this study found

BRJ increased pre-exercise plasma NO2- versus placebo. During steady-state exercise, BRJ reduced VO2 and increased SpO2 at both altitudes; time-trial performance improved by 3.8% at 3,000 m (BRJ 1,653.9 s vs PLA 1,718.7 s) and 4.2% at 4,300 m (BRJ 1,809.8 s vs PLA 1,889.1 s). Gastrocnemius muscle oxygenation (TSI) increased with BRJ during the TT. Cognitive performance did not differ between BRJ and placebo. Conclusion: BRJ improves physiological function and endurance performance during simulated altitude hiking but does not enhance cognitive function.

Study & population

Ten healthy, non-smoking, normotensive men (mean age 23 years; VO2max 60.9 ml/kg/min) participated in a randomized, double-blind, placebo-controlled, cross-over trial.

Intervention

Acute supplementation prior to each trial: 140 ml nitrate-rich beetroot juice (~12.5 mmol NO3-) or nitrate-depleted placebo beetroot juice (~0.01 mmol NO3-); consumed 2 hours before each trial.

Key limitation

Small sample size (n=10); all male; conducted in normobaric hypoxia (not terrestrial altitude); ventilation data not collected; cognitive outcomes limited to a specific test battery; results may not generalize to women or other populations.

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Original abstract