Document Detail


Acute and chronic effects of dietary nitrate supplementation on blood pressure and the physiological responses to moderate-intensity and incremental exercise.
MedLine Citation:
PMID:  20702806     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Dietary nitrate (NO(3)(-)) supplementation with beetroot juice (BR) over 4-6 days has been shown to reduce the O(2) cost of submaximal exercise and to improve exercise tolerance. However, it is not known whether shorter (or longer) periods of supplementation have similar (or greater) effects. We therefore investigated the effects of acute and chronic NO(3)(-) supplementation on resting blood pressure (BP) and the physiological responses to moderate-intensity exercise and ramp incremental cycle exercise in eight healthy subjects. Following baseline tests, the subjects were assigned in a balanced crossover design to receive BR (0.5 l/day; 5.2 mmol of NO(3)(-)/day) and placebo (PL; 0.5 l/day low-calorie juice cordial) treatments. The exercise protocol (two moderate-intensity step tests followed by a ramp test) was repeated 2.5 h following first ingestion (0.5 liter) and after 5 and 15 days of BR and PL. Plasma nitrite concentration (baseline: 454 ± 81 nM) was significantly elevated (+39% at 2.5 h postingestion; +25% at 5 days; +46% at 15 days; P < 0.05) and systolic and diastolic BP (baseline: 127 ± 6 and 72 ± 5 mmHg, respectively) were reduced by ∼4% throughout the BR supplementation period (P < 0.05). Compared with PL, the steady-state Vo(2) during moderate exercise was reduced by ∼4% after 2.5 h and remained similarly reduced after 5 and 15 days of BR (P < 0.05). The ramp test peak power and the work rate at the gas exchange threshold (baseline: 322 ± 67 W and 89 ± 15 W, respectively) were elevated after 15 days of BR (331 ± 68 W and 105 ± 28 W; P < 0.05) but not PL (323 ± 68 W and 84 ± 18 W). These results indicate that dietary NO(3)(-) supplementation acutely reduces BP and the O(2) cost of submaximal exercise and that these effects are maintained for at least 15 days if supplementation is continued.
Authors:
Anni Vanhatalo; Stephen J Bailey; Jamie R Blackwell; Fred J DiMenna; Toby G Pavey; Daryl P Wilkerson; Nigel Benjamin; Paul G Winyard; Andrew M Jones
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Publication Detail:
Type:  Journal Article; Randomized Controlled Trial     Date:  2010-08-11
Journal Detail:
Title:  American journal of physiology. Regulatory, integrative and comparative physiology     Volume:  299     ISSN:  1522-1490     ISO Abbreviation:  Am. J. Physiol. Regul. Integr. Comp. Physiol.     Publication Date:  2010 Oct 
Date Detail:
Created Date:  2010-10-01     Completed Date:  2010-10-19     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  100901230     Medline TA:  Am J Physiol Regul Integr Comp Physiol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  R1121-31     Citation Subset:  IM    
Affiliation:
Univ. of Exeter, UK.
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MeSH Terms
Descriptor/Qualifier:
Adult
Anaerobic Threshold / drug effects,  physiology
Beta vulgaris / chemistry*
Blood Pressure / drug effects*,  physiology*
Cross-Over Studies
Dietary Supplements
Exercise / physiology*
Exercise Test
Female
Humans
Lactic Acid / blood
Male
Nitrates / pharmacology*
Nitric Oxide / blood
Oxygen Consumption / drug effects,  physiology
Physical Fitness / physiology*
Pulmonary Gas Exchange / physiology
Respiratory Mechanics / drug effects,  physiology
Chemical
Reg. No./Substance:
0/Nitrates; 10102-43-9/Nitric Oxide; 50-21-5/Lactic Acid

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


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