| Dependence of muscle VO2 on blood flow dynamics at onset of forearm exercise. | |
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MedLine Citation:
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PMID: 8904578 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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The hypothesis that the rate of increase in muscle O2 uptake (VO2mus) at the onset of exercise is influenced by muscle blood flow was tested during forearm exercise with the arm either above or below heart level to modify perfusion pressure. Ten young men exercised at a power of approximately 2.2 W, and five of these subjects also worked at 1.4 W. Blood flow to the forearm was calculated from the product of blood velocity and cross-sectional area obtained with Doppler techniques. Venous blood was sampled from a deep forearm vein to determine O2 extraction. The rate of increase in VO2mus and blood flow was assessed from the mean response time (MRT), which is the time to achieve approximately 63% increase from baseline to steady state. In the arm below heart position during the 2.2-W exercise, blood flow and VO2mus both increased, with a MRT of approximately 30 s. With the arm above the heart at this power, the MRTs for blood flow [79.8 +/- 15.7 (SE)s] and VO2mus (50.2 +/- 4.0 s) were both significantly slower. Consistent with these findings were the greater increases in venous plasma lactate concentration over resting valued in the above heart position (2.8 +/- 0.4 mmol/l) than in the below heart position (0.9 +/- mmol/l). At the lower power, both blood flow and VO2mus also increased more rapidly with the arm below compared with above the heart. These data support the hypothesis that changes in blood flow at the onset of exercise have a direct effect on oxidative metabolism through alterations in O2 transport. |
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Authors:
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R L Hughson; J K Shoemaker; M E Tschakovsky; J M Kowalchuk |
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Publication Detail:
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Type: Clinical Trial; Controlled Clinical Trial; Journal Article; Research Support, Non-U.S. Gov't |
Journal Detail:
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Title: Journal of applied physiology (Bethesda, Md. : 1985) Volume: 81 ISSN: 8750-7587 ISO Abbreviation: J. Appl. Physiol. Publication Date: 1996 Oct |
Date Detail:
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Created Date: 1997-02-19 Completed Date: 1997-02-19 Revised Date: 2006-11-15 |
Medline Journal Info:
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Nlm Unique ID: 8502536 Medline TA: J Appl Physiol Country: UNITED STATES |
Other Details:
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Languages: eng Pagination: 1619-26 Citation Subset: IM; S |
Affiliation:
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Department of Kinesiology, University of Waterloo, Ontario, Canada. hughson@cgsa.uwaterloo.ca |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Adult Blood Pressure / physiology Exercise / physiology* Forearm / blood supply*, physiology Heart Rate / physiology Humans Laser-Doppler Flowmetry Male Muscle, Skeletal / blood supply*, metabolism* Oxygen Consumption / physiology* Regional Blood Flow / physiology |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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