Document Detail


Dietary nitrate supplementation reduces the O2 cost of walking and running: a placebo-controlled study.
MedLine Citation:
PMID:  21071588     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Dietary supplementation with beetroot juice (BR) has been shown to reduce resting blood pressure and the O(2) cost of submaximal exercise and to increase tolerance to high-intensity cycling. We tested the hypothesis that the physiological effects of BR were consequent to its high NO(3)(-) content per se, and not the presence of other potentially bioactive compounds. We investigated changes in blood pressure, mitochondrial oxidative capacity (Q(max)), and physiological responses to walking and moderate- and severe-intensity running following dietary supplementation with BR and NO(3)(-)-depleted BR [placebo (PL)]. After control (nonsupplemented) tests, nine healthy, physically active male subjects were assigned in a randomized, double-blind, crossover design to receive BR (0.5 l/day, containing ∼6.2 mmol of NO(3)(-)) and PL (0.5 l/day, containing ∼0.003 mmol of NO(3)(-)) for 6 days. Subjects completed treadmill exercise tests on days 4 and 5 and knee-extension exercise tests for estimation of Q(max) (using (31)P-magnetic resonance spectroscopy) on day 6 of the supplementation periods. Relative to PL, BR elevated plasma NO(2)(-) concentration (183 ± 119 vs. 373 ± 211 nM, P < 0.05) and reduced systolic blood pressure (129 ± 9 vs. 124 ± 10 mmHg, P < 0.01). Q(max) was not different between PL and BR (0.93 ± 0.05 and 1.05 ± 0.22 mM/s, respectively). The O(2) cost of walking (0.87 ± 0.12 and 0.70 ± 0.10 l/min in PL and BR, respectively, P < 0.01), moderate-intensity running (2.26 ± 0.27 and 2.10 ± 0.28 l/min in PL and BR, respectively, P < 0.01), and severe-intensity running (end-exercise O(2) uptake = 3.77 ± 0.57 and 3.50 ± 0.62 l/min in PL and BL, respectively, P < 0.01) was reduced by BR, and time to exhaustion during severe-intensity running was increased by 15% (7.6 ± 1.5 and 8.7 ± 1.8 min in PL and BR, respectively, P < 0.01). In contrast, relative to control, PL supplementation did not alter plasma NO(2)(-) concentration, blood pressure, or the physiological responses to exercise. These results indicate that the positive effects of 6 days of BR supplementation on the physiological responses to exercise can be ascribed to the high NO(3)(-) content per se.
Authors:
Katherine E Lansley; Paul G Winyard; Jonathan Fulford; Anni Vanhatalo; Stephen J Bailey; Jamie R Blackwell; Fred J DiMenna; Mark Gilchrist; Nigel Benjamin; Andrew M Jones
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Publication Detail:
Type:  Journal Article; Randomized Controlled Trial     Date:  2010-11-11
Journal Detail:
Title:  Journal of applied physiology (Bethesda, Md. : 1985)     Volume:  110     ISSN:  1522-1601     ISO Abbreviation:  J. Appl. Physiol.     Publication Date:  2011 Mar 
Date Detail:
Created Date:  2011-03-09     Completed Date:  2011-07-07     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:  591-600     Citation Subset:  IM    
Affiliation:
School of Sport and Health Sciences, St. Luke's Campus, Univ. of Exeter, Heavitree Rd., Exeter EX1 2LU, UK.
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MeSH Terms
Descriptor/Qualifier:
Administration, Oral
Beta vulgaris / chemistry*
Beverages
Dietary Supplements*
Gait / drug effects,  physiology
Humans
Male
Nitrates / administration & dosage*
Oxygen Consumption / drug effects,  physiology*
Plant Extracts / administration & dosage*
Running / physiology*
Walking / physiology*
Young Adult
Chemical
Reg. No./Substance:
0/Nitrates; 0/Plant Extracts
Comments/Corrections
Comment In:
J Appl Physiol (1985). 2011 Mar;110(3):585-6   [PMID:  21183624 ]

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