Document Detail


Effects of consecutive days of exercise and recovery on muscle mechanical function.
MedLine Citation:
PMID:  18202569     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
PURPOSE: To investigate the effects of three consecutive days of prolonged exercise on muscle mechanical function, 12 volunteers (.VO(2peak) = 44.8 +/- 2.0 mL.kg(-1).min(-1), mean +/- SE) cycled at approximately 60% .VO(2peak) until fatigue. METHODS: Quadriceps muscle function was assessed before and after exercise on day 1 (E1) and day 3 (E3) and during three consecutive days of recovery (R1, R2, R3), using both voluntary and electrically induced contractions at various stimulation frequencies. RESULTS: Exercise on E1 and E3 resulted in a 40% (120 +/- 12 vs 72 +/- 10 N) and 35% (117 +/- 14 vs 78 +/- 8 N) deficit (P < 0.05) in force at 10 Hz, respectively, which remained depressed (P < 0.05) by 32-34% during R1-R3. At 100 Hz, force, although not altered by exercise at E1 or E3, was decreased (P < 0.05) by 12-16% during recovery. The maximal rate of relaxation (-dF/dtmax) at 10 Hz was reduced (P < 0.05) by 38% on E1, by 32% on E3, and remained depressed by 38% through R3. At 100 Hz, -dF/dtmax was only depressed (P < 0.05) during recovery. Maximal rate of force development (+dF/dtmax) at 10 Hz was reduced (P < 0.05) by exercise, but not in recovery. Maximal voluntary contraction force was depressed (P < 0.05) with exercise at both E1 and E3 and remained depressed (P < 0.05) throughout recovery. The reduction (P < 0.05) in motor unit activation assessed with the interpolated twitch technique, observed during recovery, suggests that part of the incomplete recovery (weakness) is central in origin. CONCLUSIONS: These results demonstrate that three consecutive days of prolonged exercise result in a weakness that persists for at least 3 d, compromising force during both voluntary and induced contractions.
Authors:
Riley D Stewart; Todd A Duhamel; Sharon Rich; A Russell Tupling; Howard J Green
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Medicine and science in sports and exercise     Volume:  40     ISSN:  0195-9131     ISO Abbreviation:  Med Sci Sports Exerc     Publication Date:  2008 Feb 
Date Detail:
Created Date:  2008-01-22     Completed Date:  2008-04-15     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  8005433     Medline TA:  Med Sci Sports Exerc     Country:  United States    
Other Details:
Languages:  eng     Pagination:  316-25     Citation Subset:  IM; S    
Affiliation:
Department of Kinesiology, University of Waterloo, Waterloo, Ontario, Canada.
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MeSH Terms
Descriptor/Qualifier:
Adolescent
Adult
Electromyography
Exercise / physiology*
Female
Humans
Male
Muscle Contraction / physiology
Muscle Fatigue / physiology
Ontario
Oxygen Consumption
Physical Endurance / physiology
Quadriceps Muscle / physiology*
Time Factors

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


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