Document Detail

Simultaneous 31P-NMR spectroscopy and EMG in exercising and recovering human skeletal muscle: a correlation study.
MedLine Citation:
PMID:  8594002     Owner:  NLM     Status:  MEDLINE    
A large number of studies have shown amplitude and spectral changes of the electromyogram during exercise, leading to several theories of how these changes might be related to the underlying metabolic changes. The amplitude and spectral changes are generally interpreted as changes in motor unit recruitment and a reduction of the muscle fiber conduction velocity due to proton or lactate accumulation. This study focuses on the causality of spectral changes of the surface electromyogram and proton or lactate accumulation and how the changes in motor unit recruitment are related to the metabolic status of the muscle. Simultaneous 31P-nuclear magnetic resonance spectroscopy and surface electromyography were performed during sustained static exercise and recovery in healthy volunteers and a patient with McArdle's disease. A clear dissociation between the median power frequency of the surface electromyogram and pH was seen in the healthy volunteers during recovery and during exercise in the patient with McArdle's disease. The results indicate that proton or lactate accumulation is not primarily responsible for the spectral changes of the surface electromyogram as previously suggested. The motor unit recruitment (as judged by the root mean square of the surface electromyogram) increased hyperbolically during the submaximal static exercise, with decreasing phosphocreatine-to-P(i) ratio reaching maximum at 0.6 (exhaustion), and seems to constitute a consistent metabolic limit to the exercise. The increased myoelectrical activity seen after exercise is not caused by an incomplete recovery of phosphorous metabolism, pH, or lactate but could probably be an impairment of the excitation-contraction coupling.
P Vestergaard-Poulsen; C Thomsen; T Sinkjaer; O Henriksen
Publication Detail:
Type:  Comparative Study; Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Journal of applied physiology (Bethesda, Md. : 1985)     Volume:  79     ISSN:  8750-7587     ISO Abbreviation:  J. Appl. Physiol.     Publication Date:  1995 Nov 
Date Detail:
Created Date:  1996-04-09     Completed Date:  1996-04-09     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:  1469-78     Citation Subset:  IM; S    
Danish Research Center of Magnetic Resonance, Hvidovre Hospital, University of Copenhagen, Denmark.
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MeSH Terms
Exercise / physiology*
Glycogen Storage Disease Type V / physiopathology
Hydrogen-Ion Concentration
Magnetic Resonance Spectroscopy
Muscle Fatigue / physiology
Muscle, Skeletal / physiology*,  physiopathology
Reference Values
Reg. No./Substance:

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