| Interaction between hypoxia and training on NIRS signal during exercise: contribution of a mathematical model. | |
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MedLine Citation:
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PMID: 19712759 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Acute exposure to hypoxia provokes a decrease in peak oxygen consumption ( V(O)(2peak)). At and above 4000 m, the decrease in V(O)(2peak) is greater than expected from the decrease in arterial oxygen content (C(a)O(2)) suggesting the participation of other factors. We hypothesized that O(2) transfer within the active muscle may play a role. Therefore we used Near Infra Red Spectroscopy (NIRS) to assess oxy (O2Hb) and deoxyhemoglobin (HHb) concentration in the vastus lateralis of trained athletes (TA) and untrained subjects (US) exercising at various inspired oxygen pressure (PI(O)(2), 131.4, 107.3 and 87.0 mmHg). A mathematical model has been developed to compute: (i) the pulmonary (K(p)) and muscular (K(tm)) O(2) diffusion coefficients and (ii) the proportion of arteriolar:capillary:venous blood participating in the NIRS signal at every exercise intensity from rest to peak exercise in the normoxic and various hypoxic conditions. In TA, O2Hb decreased near maximal exercise at 2500 and 4000 m, while in US, altitude had no effect. In normoxia O2Hb was higher in TA than in US, the difference disappearing in hypoxia. K(tm) increased linearly with workload and altitude and was higher in TA than US while K(p) plateaued near maximal exercise, which was consistent with athletes' greater decrease in C(a)O(2). The greater participation of arterial blood in the NIRS signal in TA at altitudes account for their higher O2Hb values as well as the greater decrease they underwent in hypoxia. At 4000m, athletes loose their advantages of adaptation to training due to a reduced arterial content, and both from NIRS variables and model output, characteristics of O(2) transfer of TA converge toward those of US. |
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Authors:
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Nicolas Bourdillon; Pascal Mollard; Murielle Letournel; Mich?le Beaudry; Jean-Paul Richalet |
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Publication Detail:
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Type: Journal Article Date: 2009-08-25 |
Journal Detail:
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Title: Respiratory physiology & neurobiology Volume: 169 ISSN: 1878-1519 ISO Abbreviation: Respir Physiol Neurobiol Publication Date: 2009 Oct |
Date Detail:
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Created Date: 2009-10-05 Completed Date: 2009-12-09 Revised Date: 2010-04-16 |
Medline Journal Info:
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Nlm Unique ID: 101140022 Medline TA: Respir Physiol Neurobiol Country: Netherlands |
Other Details:
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Languages: eng Pagination: 50-61 Citation Subset: IM |
Affiliation:
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Universit? Paris 13, Laboratoire "R?ponses cellulaires et fonctionnelles ? l'hypoxie" EA 2363, Bobigny, France. |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Adult Anoxia / blood*, pathology Blood Gas Analysis / methods Exercise / physiology* Exercise Test Heart Rate / physiology Hemoglobins / metabolism Humans Male Models, Biological* Models, Theoretical* Multivariate Analysis Physical Endurance / physiology* Pulmonary Alveoli / physiopathology Spectroscopy, Near-Infrared / methods Young Adult |
| Chemical | |
Reg. No./Substance:
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0/Hemoglobins |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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