Document Detail

Postmarathon paradox: insulin resistance in the face of glycogen depletion.
MedLine Citation:
PMID:  8779957     Owner:  NLM     Status:  MEDLINE    
Acute physical exercise enhances insulin sensitivity in healthy subjects. We examined the effect of a 42-km marathon run on insulin sensitivity and lipid oxidation in 19 male runners. In the morning after the marathon run, basal serum free fatty acid concentration was 2.2-fold higher, muscle glycogen content 37% lower (P < 0.01), glycogen synthase fractional activity 56% greater (P < 0.01), and glucose oxidation reduced by 43% (P < 0.01), whereas lipid oxidation was increased by 55% (P < 0.02) compared with the control study. During euglycemic-hyperinsulinemic clamp, whole body glucose disposal was decreased by 12% (P < 0.01) because of a 36% lower glucose oxidation rate (P < 0.05), whereas the rate of lipid oxidation was 10-fold greater (P < 0.02) than in the control study. After the marathon, muscle glycogen content correlated positively with lipid oxidation (r = 0.60, P < 0.05) and maximal aerobic power (Vo2peak; r = 0.61, P < 0.05). Vo2peak correlated positively with basal lipid oxidation (r = 0.57, P < 0.05). In conclusion, 1) after the marathon run, probably because of increased lipid oxidation, the insulin-stimulated glucose disposal is decreased despite muscle glycogen depletion and the activation of glycogen synthase; 2) the contribution of lipid oxidation in energy expenditure is increased in proportion to physical fitness; 3) these adaptations of fuel homeostasis may contribute to the maintenance of physical performance after prolonged exercise.
J A Tuominen; P Ebeling; R Bourey; L Koranyi; A Lamminen; J Rapola; T Sane; H Vuorinen-Markkola; V A Koivisto
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  The American journal of physiology     Volume:  270     ISSN:  0002-9513     ISO Abbreviation:  Am. J. Physiol.     Publication Date:  1996 Feb 
Date Detail:
Created Date:  1996-12-20     Completed Date:  1996-12-20     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  0370511     Medline TA:  Am J Physiol     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  E336-43     Citation Subset:  IM    
Department of Medicine, Helsinki University Central Hospital, Finland.
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MeSH Terms
Blood / metabolism
Energy Metabolism
Glucose / metabolism
Glucose Transporter Type 4
Glycogen / deficiency*,  metabolism
Glycogen Synthase / genetics,  metabolism
Insulin Resistance*
Lipid Metabolism
Magnetic Resonance Imaging
Monosaccharide Transport Proteins / genetics,  metabolism
Muscle Proteins*
Muscles / anatomy & histology,  metabolism
Physical Endurance*
RNA, Messenger / metabolism
Reg. No./Substance:
0/Glucose Transporter Type 4; 0/Monosaccharide Transport Proteins; 0/Muscle Proteins; 0/RNA, Messenger; 0/SLC2A4 protein, human; 50-99-7/Glucose; 9005-79-2/Glycogen; EC Synthase

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