Document Detail

Effect of initial muscle glycogen levels on protein catabolism during exercise.
MedLine Citation:
PMID:  7380688     Owner:  NLM     Status:  MEDLINE    
Serum urea increases with exercise duration suggest prolonged exercise may be analogous to starvation where protein catabolism is known to occur. The purpose of this investigation was to alter muscle glycogen levels and to study the effect on protein catabolism. Six subjects (27-30 yr) pedaled a cycle ergometer for 1 h at 61% VO2max (mean VO2 = 2.33 +/- 0.7 1 . min-1) 1) after CHO loading (CHOL) and 2) after CHO depletion (CHOD). The following urea N measures were made: pre-exercise serum and urine, exercise serum and sweat (15-min serial samples), and serum and urine during 240 recovery min. Results demonstrated that 1) exercise serum urea N increased in CHOD attaining significance (P less than 0.01) at 60 min; 2) serum urea N increases continued into recovery at all measurement points of CHOD (P less than 0.01) and at 240 min of CHOL (P less than 0.05); 3) sweat urea N increased 154.2-fold (CHOD) and 65.6-fold (CHOL) (P less than 0.05). Calculations indicate that CHOD sweat urea N excretion was equivalent to a protein breakdown of 13.7 g . h-1 or 10.4% of the total caloric cost. It was concluded that protein is utilized during exercise to a greater extent than is generally assumed and that under certain conditions protein carbon may contribute significantly to exercise caloric cost.
P W Lemon; J P Mullin
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Journal of applied physiology: respiratory, environmental and exercise physiology     Volume:  48     ISSN:  0161-7567     ISO Abbreviation:  J Appl Physiol Respir Environ Exerc Physiol     Publication Date:  1980 Apr 
Date Detail:
Created Date:  1980-08-15     Completed Date:  1980-08-15     Revised Date:  2013-09-26    
Medline Journal Info:
Nlm Unique ID:  7801242     Medline TA:  J Appl Physiol Respir Environ Exerc Physiol     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  624-9     Citation Subset:  IM; S    
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MeSH Terms
Glycogen / metabolism*
Muscles / metabolism*
Physical Exertion*
Proteins / metabolism*
Sweat / metabolism
Time Factors
Urea / metabolism*,  urine
Reg. No./Substance:
0/Proteins; 57-13-6/Urea; 9005-79-2/Glycogen

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

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