Document Detail

Muscle oxygen kinetics at onset of intense dynamic exercise in humans.
MedLine Citation:
PMID:  10956247     Owner:  NLM     Status:  MEDLINE    
The present study examined the onset and the rate of rise of muscle oxidation during intense exercise in humans and whether oxygen availability limits muscle oxygen uptake in the initial phase of intense exercise. Six subjects performed 3 min of intense one-legged knee-extensor exercise [65.3 +/- 3.7 (means +/- SE) W]. The femoral arteriovenous blood mean transit time (MTT) and time from femoral artery to muscle microcirculation was determined to allow for an examination of the oxygen uptake at capillary level. MTT was 15.3 +/- 1.8 s immediately before exercise, 10.4 +/- 0.7 s after 6 s of exercise, and 4.7 +/- 0.5 s at the end of exercise. Arterial venous O(2) difference (a-v(diff) O(2)) of 18 +/- 5 ml/l before the exercise was unchanged after 2 s, but it increased (P < 0.05) after 6 s of exercise to 43 +/- 10 ml/l and reached 146 +/- 4 ml/l at the end of exercise. Thigh oxygen uptake increased (P < 0.05) from 32 +/- 8 to 102 +/- 28 ml/min after 6 s of exercise and to 789 +/- 88 ml/min at the end of exercise. The time to reach half-peak a-v(diff) O(2) and thigh oxygen uptake was 13 +/- 2 and 25 +/- 3 s, respectively. The difference between thigh oxygen delivery (blood flow x arterial oxygen content) and thigh oxygen uptake increased (P < 0.05) after 6 s and returned to preexercise level after 14 s. The present data suggest that, at the onset of exercise, oxygen uptake of the exercising muscles increases after a delay of only a few seconds, and oxygen extraction peaks after approximately 50 s of exercise. The limited oxygen utilization in the initial phase of intense exercise is not caused by insufficient oxygen availability.
J Bangsbo; P Krustrup; J González-Alonso; R Boushel; B Saltin
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  American journal of physiology. Regulatory, integrative and comparative physiology     Volume:  279     ISSN:  0363-6119     ISO Abbreviation:  Am. J. Physiol. Regul. Integr. Comp. Physiol.     Publication Date:  2000 Sep 
Date Detail:
Created Date:  2000-10-05     Completed Date:  2000-10-05     Revised Date:  2008-11-21    
Medline Journal Info:
Nlm Unique ID:  100901230     Medline TA:  Am J Physiol Regul Integr Comp Physiol     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  R899-906     Citation Subset:  IM; S    
Institute of Exercise and Sport Sciences, Copenhagen Muscle Research Centre, The August Krogh Institute, University of Copenhagen, DK-2100 Copenhagen, Denmark. JBANGSBO@AKI.KU.DK
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MeSH Terms
Blood Flow Velocity / physiology
Blood Gas Analysis
Capillaries / physiology
Femoral Artery / physiology
Femoral Vein / physiology
Hydrogen-Ion Concentration
Muscle, Skeletal / blood supply*,  metabolism*
Oxygen / blood,  pharmacokinetics*
Oxygen Consumption / physiology
Physical Exertion / physiology*
Reg. No./Substance:
Comment In:
Am J Physiol Regul Integr Comp Physiol. 2001 Aug;281(2):R681-2   [PMID:  11488269 ]

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

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