Document Detail

Impaired action potential conduction at high force levels after eccentric exercise.
MedLine Citation:
PMID:  19880328     Owner:  NLM     Status:  MEDLINE    
High-density surface electromyography was used to examine whether gross sarcolemmal function is impaired in m. biceps brachii after intensive eccentric elbow flexor exercise, when measured at wide range of isometric contraction levels. Root mean square (RMS), mean power frequency (MNF) and mean muscle fibre conduction velocity (CV) were calculated before and up to four days post-exercise. Maximal isometric voluntary (MVC) force decreased by 21.3+/-5.6% two hours after exercise, and by 12.6+/-11.1% two days post-exercise. CV and MNF decreased both during MVC (CV from 4.1+/-0.3m/s to 3.8+/-0.4m/s and MNF from 92.6+/-10 Hz to 85.2+/-11 Hz) and during electrically evoked maximal M-wave (CV from 4.1+/-0.3m/s to 3.0+/-0.5m/s and MNF from 97.1+/-27.2 Hz to 78.0+/-24.4 Hz) two hours post-exercise. Furthermore, at submaximal isometric force levels, CV and MNF decreased only at higher contraction levels (40%, 50% and 75% of MVC) two hour post-exercise. It can be concluded that intensive exercise can temporarily impair gross sarcolemmal function. In addition, since this only occurred at high force levels, based on Henneman's size principle, it seems that higher threshold motor units were predominantly affected.
Harri Piitulainen; Reijo Bottas; Paavo Komi; Vesa Linnamo; Janne Avela
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2009-10-31
Journal Detail:
Title:  Journal of electromyography and kinesiology : official journal of the International Society of Electrophysiological Kinesiology     Volume:  20     ISSN:  1873-5711     ISO Abbreviation:  J Electromyogr Kinesiol     Publication Date:  2010 Oct 
Date Detail:
Created Date:  2010-08-02     Completed Date:  2011-01-04     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  9109125     Medline TA:  J Electromyogr Kinesiol     Country:  England    
Other Details:
Languages:  eng     Pagination:  879-87     Citation Subset:  IM    
Copyright Information:
Copyright (c) 2009 Elsevier Ltd. All rights reserved.
Department of Biology of Physical Activity, Neuromuscular Research Center, University of Jyväskylä, Finland.
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MeSH Terms
Action Potentials / physiology*
Muscle Contraction / physiology*
Muscle Fatigue / physiology*
Muscle, Skeletal / physiology*
Neural Conduction / physiology*
Physical Endurance / physiology*
Physical Exertion / physiology*
Stress, Mechanical

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