Document Detail

Coactivation of the elbow antagonist muscles is not affected by the speed of movement in isokinetic exercise.
MedLine Citation:
PMID:  16307438     Owner:  NLM     Status:  MEDLINE    
Since muscle coactivation increases the stiffness and stability of a joint, greater coactivation is likely during faster than slower movements. Very few studies, though, have been conducted to verify this hypothesis. Moreover, a large number of studies have examined coactivation of muscles surrounding the knee joint whereas there are few reports on the elbow joint. The aim of this study was therefore to compare the antagonist activation of the elbow flexors and extensors during isokinetic concentric exercises and to investigate the influence of angular velocity on their activation. Twelve men participated in the study. The surface electromyographic signals (sEMG) were recorded from the biceps brachii (BB) and triceps brachii (TB) muscles during three maximal voluntary isometric contractions (MVC) of elbow flexors and extensors and a set of three maximal elbow flexions and extensions each at 15 degrees, 30 degrees , 60 degrees, 120 degrees, 180 degrees, and 240 degrees.s(-1). Normalized root mean square (RMS) of sEMG was calculated during the isokinetic phase of movement as an index of sEMG amplitude. During elbow flexion, the antagonist activation of BB averaged 16.2% lower than TB, and this difference was statistically significant at all angular velocities. The normalized RMS values ranged from 26.0% +/- 19.0 at MVC to 37.8% +/- 13.9 at 240 degrees.s(-1) for antagonist TB activation, and from 5.7% +/- 5.2 at MVC to 18.9% +/- 8.6 at 240 degrees.s(-1) for antagonist BB activation. No influence of angular velocity on agonist and antagonist activity was found. Moreover, flexion and extension torques were both strongly affected by the amount of antagonist activation. The functional specialization of the two muscle groups could be responsible for the different levels of antagonist activation. The frequent use of BB, which is not assisted by gravity during daily activities, could lead to reduced coactivation due to a better functioning of the control system based upon reciprocal innervation. These findings may have significant implications in the design of rehabilitation programs directed to the elbow joint.
Ilenia Bazzucchi; Paola Sbriccoli; Giulia Marzattinocci; Francesco Felici
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Publication Detail:
Type:  Clinical Trial; Journal Article    
Journal Detail:
Title:  Muscle & nerve     Volume:  33     ISSN:  0148-639X     ISO Abbreviation:  Muscle Nerve     Publication Date:  2006 Feb 
Date Detail:
Created Date:  2006-01-23     Completed Date:  2006-04-11     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  7803146     Medline TA:  Muscle Nerve     Country:  United States    
Other Details:
Languages:  eng     Pagination:  191-9     Citation Subset:  IM    
Department of Human Movement and Sport Sciences, Istituto Universitario di Scienze Motorie, Piazza Lauro De Bosis 6, Rome, Italy.
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MeSH Terms
Data Interpretation, Statistical
Elbow / anatomy & histology,  physiology*
Elbow Joint / physiology
Exercise / physiology*
Movement / physiology*
Muscle Contraction / physiology
Muscle, Skeletal / innervation,  physiology*
Time Factors

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