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Influence of intermittent hypoxic training on muscle energetics and exercise tolerance.
MedLine Citation:
PMID:  23305980     Owner:  NLM     Status:  Publisher    
Abstract/OtherAbstract:
Intermittent hypoxic training (IHT) is sometimes used by athletes to enhance 'non-hematological' physiological adaptations to simulated altitude. We investigated whether IHT would result in greater improvements in muscle energetics and exercise tolerance compared to work-matched intermittent normoxic training (INT). Nine physically-active males completed three weeks of intensive single-leg knee-extensor exercise training. Each training session consisted of 25 min of IHT (F(I)O(2) 14.5 ± 0.1%) with the experimental leg and 25 min of INT with the alternate leg which served as a control. Before and after the training intervention, the subjects completed a test protocol consisting of a bout of sub-maximal constant-work-rate exercise, a 24 s high-intensity exercise bout to quantify the phosphocreatine recovery time constant ([PCr]-τ), and an incremental test to the limit of tolerance. The tests were completed in normoxia and hypoxia, in both the INT and IHT legs. Muscle metabolism was assessed non-invasively using (31)P-magnetic resonance spectroscopy. Improvements in the time-to-exhaustion during incremental exercise were not significantly different between training conditions either in normoxia (INT: 28 ± 20 vs. IHT: 25 ± 9 %, P=0.86) or hypoxia (INT: 21 ± 10 vs. IHT: 15 ± 11 %, P=0.29). In hypoxia, [PCr]-τ was speeded slightly but significantly more post-IHT compared to post-INT (-7.3 ± 2.9 vs. -3.7 ± 1.7 s, P<0.01) but changes in muscle metabolite concentrations during exercise were essentially not different between IHT and INT. Under the conditions of this investigation, IHT does not enhance muscle metabolic responses or incremental exercise performance compared to INT.
Authors:
Ben A Holliss; Jonathan Fulford; Anni Vanhatalo; Charles R Pedlar; Andrew M Jones
Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2013-1-10
Journal Detail:
Title:  Journal of applied physiology (Bethesda, Md. : 1985)     Volume:  -     ISSN:  1522-1601     ISO Abbreviation:  J. Appl. Physiol.     Publication Date:  2013 Jan 
Date Detail:
Created Date:  2013-1-11     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  8502536     Medline TA:  J Appl Physiol     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Affiliation:
1University of Exeter.
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