Document Detail


Peripheral circulatory factors limit rate of increase in muscle O(2) uptake at onset of heavy exercise.
MedLine Citation:
PMID:  11133896     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
We used an exercise paradigm with repeated bouts of heavy forearm exercise to test the hypothesis that alterations in local acid-base environment that remain after the first exercise result in greater blood flow and O(2) delivery at the onset of the second bout of exercise. Two bouts of handgrip exercise at 75% peak workload were performed for 5 min, separated by 5 min of recovery. We continuously measured blood flow using Doppler ultrasound and sampled venous blood for O(2) content, PCO(2), pH, and lactate and potassium concentrations, and we calculated muscle O(2) uptake (VO(2)). Forearm blood flow was elevated before the second exercise compared with the first and remained higher during the first 30 s of exercise (234 +/- 18 vs. 187 +/- 4 ml/min, P < 0.05). Flow was not different at 5 min. Arteriovenous O(2) content difference was lower before the second bout (4.6 +/- 0.9 vs. 7.2 +/- 0.7 ml O(2)/dl) and higher by 30 s of exercise (11.2 +/- 0.7 vs. 10.8 +/- 0.7 ml O(2)/dl, P < 0. 05). Muscle VO(2) was unchanged before the start of exercise but was elevated during the first 30 s of the transition to the second exercise bout (26.0 +/- 2.1 vs. 20.0 +/- 0.9 ml/min, P < 0.05). Changes in venous blood PCO(2), pH, and lactate concentration were consistent with reduced reliance on anaerobic glycolysis at the onset of the second exercise bout. These data show that limitations of muscle blood flow can restrict the adaptation of oxidative metabolism at the onset of heavy muscular exertion.
Authors:
M J MacDonald; H L Naylor; M E Tschakovsky; R L Hughson
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Journal of applied physiology (Bethesda, Md. : 1985)     Volume:  90     ISSN:  8750-7587     ISO Abbreviation:  J. Appl. Physiol.     Publication Date:  2001 Jan 
Date Detail:
Created Date:  2001-01-16     Completed Date:  2001-03-29     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:  83-9     Citation Subset:  IM    
Affiliation:
Department of Kinesiology, University of Waterloo, Waterloo, Ontario, Canada N2L 3G1.
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MeSH Terms
Descriptor/Qualifier:
Acid-Base Equilibrium
Adaptation, Physiological / physiology
Adult
Exercise / physiology*
Forearm / blood supply*
Hand Strength
Humans
Hydrogen-Ion Concentration
Lactic Acid / blood
Male
Muscle, Skeletal / blood supply*,  metabolism*
Oxygen / blood
Oxygen Consumption*
Regional Blood Flow / physiology
Time Factors
Vasodilation
Veins / metabolism
Chemical
Reg. No./Substance:
50-21-5/Lactic Acid; 7782-44-7/Oxygen

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


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