Document Detail

Influence of body position on muscle deoxy[Hb+Mb] during ramp cycle exercise.
MedLine Citation:
PMID:  20654739     Owner:  NLM     Status:  MEDLINE    
We used near-infrared spectroscopy (NIRS) to test the hypothesis that body position alters the sigmoidal response profile of muscle fractional O(2) extraction (estimated using deoxy[Hb+Mb]) during incremental cycle exercise. Seven male subjects (mean±SD age 32±13 years) completed a ramp incremental cycling test to exhaustion (30W/min) in both the supine and upright body positions. The sigmoidal (as opposed to hyperbolic) model that provided the better fit to deoxy[Hb+Mb] data during upright cycling was also present for the supine response; however, the slope of the sigmoid was increased (upright: 0.052±0.012 vs. supine: 0.090±0.036%⋅%P(peak)(-1); P<0.05) and a plateau occurred at a lower work rate (upright: 83±8 vs. supine: 68±19%P(peak)(-1); P<0.05) during supine exercise. These changes occurred in the absence of a leftward shift of the sigmoid. We also found a significantly greater deltaV(O)₂/deltaW slope above compared to below gas exchange threshold (GET) for both conditions (upright: 9.8±0.5 vs. 8.2±0.9; supine: 10.7±0.9 vs. 8.0±0.8) and for supine compared to upright cycling above GET. These findings suggest that the supine posture affects O₂ extraction and V(O)₂ kinetics to a greater extent as work rate progresses during ramp incremental exercise.
Fred J DiMenna; Stephen J Bailey; Andrew M Jones
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Publication Detail:
Type:  Journal Article     Date:  2010-07-21
Journal Detail:
Title:  Respiratory physiology & neurobiology     Volume:  173     ISSN:  1878-1519     ISO Abbreviation:  Respir Physiol Neurobiol     Publication Date:  2010 Sep 
Date Detail:
Created Date:  2010-09-13     Completed Date:  2010-12-28     Revised Date:  2011-01-13    
Medline Journal Info:
Nlm Unique ID:  101140022     Medline TA:  Respir Physiol Neurobiol     Country:  Netherlands    
Other Details:
Languages:  eng     Pagination:  138-45     Citation Subset:  IM    
Copyright Information:
Copyright 2010 Elsevier B.V. All rights reserved.
School of Sport and Health Sciences, St. Luke's Campus, University of Exeter, Heavitree Road, Exeter, Devon EX1 2LU, UK.
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MeSH Terms
Exercise / physiology*
Hemoglobins / metabolism*
Middle Aged
Muscle, Skeletal / metabolism*
Myoglobin / metabolism*
Oxygen Consumption / physiology*
Posture / physiology
Pulmonary Gas Exchange
Spectroscopy, Near-Infrared / methods
Statistics as Topic
Supine Position / physiology
Time Factors
Reg. No./Substance:
0/Hemoglobins; 0/Myoglobin; 9008-02-0/deoxyhemoglobin

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

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