Document Detail

Quadriceps metabolism during constant workrate cycling exercise in chronic obstructive pulmonary disease.
MedLine Citation:
PMID:  20966193     Owner:  NLM     Status:  MEDLINE    
Impaired resting metabolism in peripheral muscles potentially contributes to exercise intolerance in chronic obstructive pulmonary disease (COPD). This study investigated the cytosolic energy metabolism of the quadriceps, from glycogen degradation to lactate accumulation, in exercising patients with COPD, in comparison to healthy controls. We measured, in 12 patients with COPD and 10 control subjects, resting and post-cycling exercise quadriceps levels of 1) energy substrates and end products of glycolysis (glycogen, glucose, pyruvate, and lactate) and intermediate markers of glycolysis (glucose-6-phosphate, glucose-1-phosphate, fructose-6-phosphate) and 2) the activity of key enzymes involved in the regulation of glycolysis (phosphofructokinase, lactate dehydrogenase). Exercise intensity (P < 0.01), duration (P = 0.049), and total work (P < 0.01) were reduced in patients with COPD. The variations in energy substrates and end products of glycolysis after cycling exercise were of similar magnitude in patients with COPD and controls. Glucose-6-phosphate (P = 0.036) and fructose-6-phosphate (P = 0.042) were significantly elevated in patients with COPD after exercise. Phosphofructokinase (P < 0.01) and lactate dehydrogenase (P = 0.02) activities were greater in COPD. Muscle glycogen utilization (P = 0.022) and lactate accumulation (P = 0.025) per unit of work were greater in COPD. We conclude that cycling exercise induced changes in quadriceps metabolism in patients with COPD that were of similar magnitude to those of healthy controls. These intramuscular events required a much lower exercise work load and time to occur in COPD. Our data suggest a greater reliance on glycolysis during exercise in COPD, which may contribute to exercise intolerance in COPD.
Didier Saey; Bruno B Lemire; Philippe Gagnon; Eric Bombardier; A Russell Tupling; Richard Debigaré; Claude H Côté; François Maltais
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2010-10-21
Journal Detail:
Title:  Journal of applied physiology (Bethesda, Md. : 1985)     Volume:  110     ISSN:  1522-1601     ISO Abbreviation:  J. Appl. Physiol.     Publication Date:  2011 Jan 
Date Detail:
Created Date:  2011-01-13     Completed Date:  2011-08-02     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:  116-24     Citation Subset:  IM    
Centre de recherche, Institut Universitaire de cardiologie et de pneumologie de Québec, Université Laval, Sainte-Foy, Quebec, Canada.
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MeSH Terms
Exercise Test
Exercise Tolerance*
Glycogen / metabolism*
Lactic Acid / metabolism*
Muscle Contraction
Muscle Proteins / metabolism*
Muscle, Skeletal / metabolism*
Physical Exertion*
Pulmonary Disease, Chronic Obstructive / physiopathology*
Grant Support
MOP-84091//Canadian Institutes of Health Research
Reg. No./Substance:
0/Muscle Proteins; 50-21-5/Lactic Acid; 9005-79-2/Glycogen

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

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