Document Detail


Dietary nitrate supplementation reduces the O2 cost of low-intensity exercise and enhances tolerance to high-intensity exercise in humans.
MedLine Citation:
PMID:  19661447     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Pharmacological sodium nitrate supplementation has been reported to reduce the O2 cost of submaximal exercise in humans. In this study, we hypothesized that dietary supplementation with inorganic nitrate in the form of beetroot juice (BR) would reduce the O2 cost of submaximal exercise and enhance the tolerance to high-intensity exercise. In a double-blind, placebo (PL)-controlled, crossover study, eight men (aged 19-38 yr) consumed 500 ml/day of either BR (containing 11.2 +/- 0.6 mM of nitrate) or blackcurrant cordial (as a PL, with negligible nitrate content) for 6 consecutive days and completed a series of "step" moderate-intensity and severe-intensity exercise tests on the last 3 days. On days 4-6, plasma nitrite concentration was significantly greater following dietary nitrate supplementation compared with PL (BR: 273 +/- 44 vs. PL: 140 +/- 50 nM; P < 0.05), and systolic blood pressure was significantly reduced (BR: 124 +/- 2 vs. PL: 132 +/- 5 mmHg; P < 0.01). During moderate exercise, nitrate supplementation reduced muscle fractional O2 extraction (as estimated using near-infrared spectroscopy). The gain of the increase in pulmonary O2 uptake following the onset of moderate exercise was reduced by 19% in the BR condition (BR: 8.6 +/- 0.7 vs. PL: 10.8 +/- 1.6 ml.min(-1).W(-1); P < 0.05). During severe exercise, the O2 uptake slow component was reduced (BR: 0.57 +/- 0.20 vs. PL: 0.74 +/- 0.24 l/min; P < 0.05), and the time-to-exhaustion was extended (BR: 675 +/- 203 vs. PL: 583 +/- 145 s; P < 0.05). The reduced O2 cost of exercise following increased dietary nitrate intake has important implications for our understanding of the factors that regulate mitochondrial respiration and muscle contractile energetics in humans.
Authors:
Stephen J Bailey; Paul Winyard; Anni Vanhatalo; Jamie R Blackwell; Fred J Dimenna; Daryl P Wilkerson; Joanna Tarr; Nigel Benjamin; Andrew M Jones
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Publication Detail:
Type:  Journal Article; Randomized Controlled Trial     Date:  2009-08-06
Journal Detail:
Title:  Journal of applied physiology (Bethesda, Md. : 1985)     Volume:  107     ISSN:  1522-1601     ISO Abbreviation:  J. Appl. Physiol.     Publication Date:  2009 Oct 
Date Detail:
Created Date:  2009-10-16     Completed Date:  2009-12-24     Revised Date:  2013-09-26    
Medline Journal Info:
Nlm Unique ID:  8502536     Medline TA:  J Appl Physiol (1985)     Country:  United States    
Other Details:
Languages:  eng     Pagination:  1144-55     Citation Subset:  IM    
Affiliation:
Exeter Univ., Sport and Health Sciences, St. Luke's Campus, Heavitree Rd., Exeter, EX1 2LU UK.
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MeSH Terms
Descriptor/Qualifier:
Administration, Oral
Adult
Beta vulgaris*
Beverages
Bicycling
Blood Pressure / drug effects
Cross-Over Studies
Dietary Supplements*
Double-Blind Method
Exercise*
Exercise Tolerance / drug effects*
Hemoglobins / metabolism
Humans
Male
Muscle Contraction*
Muscle Fatigue / drug effects
Muscle, Skeletal / drug effects*,  metabolism
Nitrites / administration & dosage*,  blood
Oxygen Consumption / drug effects*
Oxyhemoglobins / metabolism
Plant Preparations / administration & dosage*
Plant Roots
Spectroscopy, Near-Infrared
Time Factors
Young Adult
Chemical
Reg. No./Substance:
0/Hemoglobins; 0/Nitrites; 0/Oxyhemoglobins; 0/Plant Preparations; 9008-02-0/deoxyhemoglobin
Comments/Corrections
Comment In:
J Appl Physiol (1985). 2009 Nov;107(5):1677; author reply 1678   [PMID:  19890035 ]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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