Document Detail

Dietary nitrate supplementation: effects on plasma nitrite and pulmonary O2 uptake dynamics during exercise in hypoxia and normoxia.
MedLine Citation:
PMID:  25009219     Owner:  NLM     Status:  Publisher    
We investigated the effects of dietary nitrate (NO3 (-)) supplementation on the concentration of plasma nitrite ([NO2 (-)]), oxygen uptake (VO2) kinetics and exercise tolerance in normoxia (N) and hypoxia (H). In a double-blind, crossover study, twelve healthy subjects completed cycle exercise tests, twice in N (20.9% O2) and twice in H (13.1% O2). Subjects ingested either 140 ml∙d(-1) of NO3 (-)-rich beetroot juice (8.4 mmol NO3; BR) or NO3 (-)-depleted beetroot juice (PL) for 3-days prior to moderate-intensity and severe-intensity exercise tests in H and N. Resting plasma [NO2 (-)] was significantly elevated in H-BR and N-BR compared to H-PL and N-PL (P<0.05). The rate of decline in plasma [NO2 (-)] was greater (P<0.05) during severe-intensity exercise in H-BR (-30±22 nM∙min(-1)) compared to H-PL (-7±10 nM∙min(-1)) and in N-BR (-26±19 nM∙ min(-1)) compared to N-PL (-1±6 nM∙ min(-1)). During moderate-intensity exercise, steady-state pulmonary VO2 was lower in H-BR (1.91±0.28 L∙min(-1)) compared to H-PL (2.05±0.25 L∙min(-1), P<0.05) and VO2 kinetics was faster in H-BR (τ: 24±13 s) compared to H-PL (31±11 s, P<0.05). NO3 (-) supplementation had no significant effect on VO2 kinetics during severe-intensity exercise in hypoxia, or during moderate-intensity or severe-intensity exercise in normoxia. Tolerance to severe-intensity exercise was improved by NO3 (-) in hypoxia (H-PL:197±28 vs. H-BR:214±43 s, P<0.05) but not normoxia. The metabolism of NO2 (-) during exercise is altered by both hypoxia and NO3 (-) supplementation. In hypoxia, NO3 (-) supplementation enhances VO2 kinetics during moderate-intensity exercise and improves severe-intensity exercise tolerance. These findings may have important implications for individuals exercising at altitude.
James Kelly; Anni Vanhatalo; Stephen J Bailey; Lee J Wylie; Christopher Tucker; Stephen List; Paul G Winyard; Andrew M Jones
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Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2014-7-9
Journal Detail:
Title:  American journal of physiology. Regulatory, integrative and comparative physiology     Volume:  -     ISSN:  1522-1490     ISO Abbreviation:  Am. J. Physiol. Regul. Integr. Comp. Physiol.     Publication Date:  2014 Jul 
Date Detail:
Created Date:  2014-7-10     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  100901230     Medline TA:  Am J Physiol Regul Integr Comp Physiol     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Copyright Information:
Copyright © 2014, American Journal of Physiology - Regulatory, Integrative and Comparative Physiology.
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