Document Detail

Effect of arterial oxygenation on quadriceps fatigability during isolated muscle exercise.
MedLine Citation:
PMID:  17122329     Owner:  NLM     Status:  MEDLINE    
The effect of various levels of oxygenation on quadriceps muscle fatigability during isolated muscle exercise was assessed in six male subjects. Twitch force (Q(tw)) was assessed using supramaximal magnetic femoral nerve stimulation. In experiment 1, maximal voluntary contraction (MVC) and Q(tw) of resting quadriceps muscle were measured in normoxia [inspired O(2) fraction (Fi(O(2))) = 0.21, percent arterial O(2) saturation (Sp(O(2))) = 98.4%, estimated arterial O(2) content (Ca(O(2))) = 20.8 ml/dl], acute hypoxia (Fi(O(2)) = 0.11, Sp(O(2)) = 74.6%, Ca(O(2)) = 15.7 ml/dl), and acute hyperoxia (Fi(O(2)) = 1.0, Sp(O(2)) = 100%, Ca(O(2)) = 22.6 ml/dl). No significant differences were found for MVC and Q(tw) among the three Fi(O(2)) levels. In experiment 2, the subjects performed three sets of nine, intermittent, isometric, unilateral, submaximal quadriceps contractions (62% MVC followed by 1 MVC in each set) while breathing each Fi(O(2)). Q(tw) was assessed before and after exercise, and myoelectrical activity of the vastus lateralis was obtained during exercise. The percent reduction of twitch force (potentiated Q(tw)) in hypoxia (-27.0%) was significantly (P < 0.05) greater than in normoxia (-21.4%) and hyperoxia (-19.9%), as were the changes in intratwitch measures of contractile properties. The increase in integrated electromyogram over the course of the nine contractions in hypoxia (15.4%) was higher (P < 0.05) than in normoxia (7.2%) or hyperoxia (6.7%). These results demonstrate that quadriceps muscle fatigability during isolated muscle exercise is exacerbated in acute hypoxia, and these effects are independent of the relative exercise intensity.
Keisho Katayama; Markus Amann; David F Pegelow; Anthony J Jacques; Jerome A Dempsey
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Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural; Research Support, Non-U.S. Gov't     Date:  2006-11-22
Journal Detail:
Title:  American journal of physiology. Regulatory, integrative and comparative physiology     Volume:  292     ISSN:  0363-6119     ISO Abbreviation:  Am. J. Physiol. Regul. Integr. Comp. Physiol.     Publication Date:  2007 Mar 
Date Detail:
Created Date:  2007-03-07     Completed Date:  2007-04-11     Revised Date:  2007-12-03    
Medline Journal Info:
Nlm Unique ID:  100901230     Medline TA:  Am J Physiol Regul Integr Comp Physiol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  R1279-86     Citation Subset:  IM    
The John Rankin Laboratory of Pulmonary Medicine, Department of Health, University of Wisconsin-Madison, 4245 Medical Science Center, 1300 University Ave., Madison, WI 53706, USA.
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MeSH Terms
Anoxia / physiopathology
Exercise / physiology*
Femoral Nerve / physiology
Isometric Contraction
Muscle Fatigue / physiology*
Oxygen / blood*,  physiology*
Oxygen Consumption / physiology
Quadriceps Muscle / innervation,  physiology*
Time Factors
Grant Support
Reg. No./Substance:

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