Document Detail

Differences between VO2 maxima of twitch and tetanic contractions are related to blood flow.
MedLine Citation:
PMID:  1917734     Owner:  NLM     Status:  MEDLINE    
The purpose of this investigation was to compare oxygen uptake (VO2) and fatigue characteristics of isotonic tetanic contractions with those observed during isotonic twitches in dog gastrocnemius-plantaris muscle. Tetanic contractions (1/s, 200-ms trains of 50 impulses/s) elicited a peak VO2 of 9.01 +/- 0.42 mumol.g-1.min-1, which declined 29% in 30 min. The peak was significantly lower during 4/s twitches (6.23 +/- 0.36 mumol.g-1.min-1), but the rate of decline was similar. Peak blood flow (Q) was 37% higher and decreased more slowly during tetanic than twitch contractions. VO2/Q and VO2/venous PO2 were similar in both groups at peak VO2 and later declined or remained constant over time. Power was significantly greater with tetanic contractions with the relative decline between 3 and 30 min similar in both groups (32 and 37%). In conclusion, tetanic contractions result in significantly higher VO2 and power than do twitch contractions. This was derived primarily from increased Q because the arteriovenous O2 difference was similar. A significant determinant of the difference in Q between twitch and tetanic contractions is mechanical hindrance of Q. There is relatively more time for unhindered flow in the tetanic contractions. In electrically stimulated muscles, maximal VO2 is related to Q and reflects mainly Q through the muscle rather than the VO2 capacity of the muscle.
W F Brechue; J K Barclay; D M O'Drobinak; W N Stainsby
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Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Journal of applied physiology (Bethesda, Md. : 1985)     Volume:  71     ISSN:  8750-7587     ISO Abbreviation:  J. Appl. Physiol.     Publication Date:  1991 Jul 
Date Detail:
Created Date:  1991-11-13     Completed Date:  1991-11-13     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:  131-5     Citation Subset:  IM    
Department of Pharmacology, University of Florida College of Medicine, Gainesville 32610.
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MeSH Terms
Electric Stimulation
Isometric Contraction
Mitochondria, Muscle / metabolism
Muscle Contraction / physiology
Muscle, Smooth, Vascular / metabolism*,  physiology
Oxygen Consumption / physiology*
Regional Blood Flow / physiology
Grant Support

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