Document Detail

Reduced short-interval intracortical inhibition after eccentric muscle damage in human elbow flexor muscles.
MedLine Citation:
PMID:  22837166     Owner:  NLM     Status:  MEDLINE    
The purpose of this study was to use paired-pulse transcranial magnetic stimulation (TMS) to examine the effect of eccentric exercise on short-interval intracortical inhibition (SICI) after damage to elbow flexor muscles. Nine young (22.5 ± 0.6 yr; mean ± SD) male subjects performed maximal eccentric exercise of the elbow flexor muscles until maximal voluntary contraction (MVC) force was reduced by ∼40%. TMS was performed before, 2 h after, and 2 days after exercise under Rest and Active (5% MVC) conditions with motor-evoked potentials (MEPs) recorded from the biceps brachii (BB) muscle. Peripheral electrical stimulation of the brachial plexus was used to assess maximal M-waves, and paired-pulse TMS with a 3-ms interstimulus interval was used to assess changes in SICI at each time point. The eccentric exercise resulted in a 34% decline in strength (P < 0.001), a 41% decline in resting M-wave (P = 0.01), changes in resting elbow joint angle (10°, P < 0.001), and a shift in the optimal elbow joint angle for force production (18°, P < 0.05) 2 h after exercise. This was accompanied by impaired muscle strength (27%, P < 0.001) and increased muscle soreness (P < 0.001) 2 days after exercise, which is indicative of muscle damage. When the test MEP amplitudes were matched between sessions, we found that SICI was reduced by 27% in resting and 23% in active BB muscle 2 h after exercise. SICI recovered 2 days after exercise when muscle pain and soreness were present, suggesting that delayed onset muscle soreness from eccentric exercise does not influence SICI. The change in SICI observed 2 h after exercise suggests that eccentric muscle damage has widespread effects throughout the motor system that likely includes changes in motor cortex.
Bradley M Pitman; John G Semmler
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Publication Detail:
Type:  Journal Article     Date:  2012-07-26
Journal Detail:
Title:  Journal of applied physiology (Bethesda, Md. : 1985)     Volume:  113     ISSN:  1522-1601     ISO Abbreviation:  J. Appl. Physiol.     Publication Date:  2012 Sep 
Date Detail:
Created Date:  2012-09-17     Completed Date:  2013-02-05     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:  929-36     Citation Subset:  IM    
Discipline of Physiology, School of Medical Sciences, The University of Adelaide, Adelaide, Australia.
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MeSH Terms
Analysis of Variance
Brachial Plexus / physiopathology
Elbow Joint / innervation*
Electric Stimulation
Evoked Potentials, Motor
Motor Cortex / physiopathology*
Muscle Contraction*
Muscle Strength
Muscle, Skeletal / innervation*,  pathology,  physiopathology
Neural Inhibition*
Pain / physiopathology
Pain Measurement
Range of Motion, Articular
Time Factors
Transcranial Magnetic Stimulation
Young Adult

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

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