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Acute dietary nitrate supplementation improves dry static apnea performance.
MedLine Citation:
PMID:  22588047     Owner:  NLM     Status:  Publisher    
Abstract/OtherAbstract:
Acute dietary nitrate (NO(3)(-)) supplementation has been reported to lower resting blood pressure, reduce the oxygen (O(2)) cost of sub-maximal exercise, and improve exercise tolerance. Given the proposed effects of NO(3)(-) on tissue oxygenation and metabolic rate, it is possible that NO(3)(-) supplementation might enhance the duration of resting apnea. If so, this might have important applications both in medicine and sport. We investigated the effects of acute NO(3)(-) supplementation on pre-apnea blood pressure, apneic duration, and the heart rate (HR) and arterial O(2) saturation (SaO(2)) responses to sub-maximal and maximal apneas in twelve well-trained apnea divers. Subjects were assigned in a randomized, double blind, crossover design to receive 70ml of beetroot juice (BR; containing ∼5.0mmol of nitrate) and placebo juice (PL; ∼0.003mmol of nitrate) treatments. At 2.5h post-ingestion, the subjects completed a series of two 2-minute (sub-maximal) static apneas separated by three minutes of rest, followed by a maximal effort apnea. Relative to PL, BR reduced resting mean arterial pressure by 2% (PL: 86±7 vs. BR: 84±6mmHg; P=0.04). The mean nadir for SaO(2) after the two sub-maximal apneas was 97.2±1.6% in PL and 98.5±0.9% in BR (P=0.03) while the reduction in HR from baseline was not significantly different between PL and BR. Importantly, BR increased maximal apneic duration by 11% (PL: 250±58 vs. BR: 278±64s; P=0.04). In the longer maximal apneas in BR, the magnitude of the reductions in HR and SaO(2) were greater than in PL (P≤0.05). The results suggest that acute dietary NO(3)(-) supplementation may increase apneic duration by reducing metabolic costs.
Authors:
Harald K Engan; Andrew M Jones; Fanny Ehrenberg; Erika Schagatay
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Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2012-5-12
Journal Detail:
Title:  Respiratory physiology & neurobiology     Volume:  -     ISSN:  1878-1519     ISO Abbreviation:  -     Publication Date:  2012 May 
Date Detail:
Created Date:  2012-5-16     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  101140022     Medline TA:  Respir Physiol Neurobiol     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Copyright Information:
Copyright © 2012. Published by Elsevier B.V.
Affiliation:
Department of Engineering and Sustainable Development, Mid Sweden University, Östersund, Sweden; Røros Rehabilitation, The Norwegian Heart and Lung Patient Organization-LHL Health, Norway.
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