Dietary nitrate supplementation increases acute mountain sickness severity and sense of effort during hypoxic exercise.

Study answer

What this study found

Nitrate increased plasma NO metabolites but did not reduce AMS or improve overall exercise performance. During 4–6 hours of hypoxia, nitrate increased headache severity by about 10 mm on a 0–100 mm scale (p=0.03) and tended to raise AMS-C (p=0.07). In AMS− participants, nitrate had no effect on headache or AMS-C but reduced ventilation during one submaximal bout (p=0.03). In AMS+ participants, nitrate increased headache severity by ~26 mm (p=0.07), raised ventilation, VO2, and mean arterial pressure during submaximal exercise, and increased sense of effort (p=0.04). Time-to-exhaustion in…

Study & population

Twenty recreationally-active men; age 22 ± 4 years; VO2max 51 ± 6 mL·kg-1·min-1.

Intervention

Daily nitrate-rich beetroot juice (70 mL; ~6.4 mmol NO3-) vs nitrate-depleted placebo (70 mL; ~0.003 mmol NO3-); ingested 2.5 hours before tests; duration: six days.

Key limitation

Male-only sample; small AMS+ subgroup; short 6-hour hypoxic exposure; potential carryover despite washout; no direct measurement of cerebral blood flow; subjective AMS assessment; limited generalizability.

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Original abstract