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Synergist coactivation and substitution pattern of the human masseter and temporalis muscles during sustained static contractions


Farella, M; Palumbo, A; Milani, S; Avecone, S; Gallo, L M; Michelotti, A (2009). Synergist coactivation and substitution pattern of the human masseter and temporalis muscles during sustained static contractions. Clinical Neurophysiology, 120(1):190-197.

Abstract

OBJECTIVE: Previous reports indicated that between-muscle substitution of active motor unit pools can be found in a variety of synergist muscles, including shoulder and leg muscles, but little information is available for the masticatory muscles. We hypothesized that, during a prolonged clenching effort performed at low- to moderate-bite force levels, a substitution pattern of activity can be found also in the masseter and anterior temporal muscles. METHODS: Ten healthy volunteers were recruited and were asked to clench unilaterally on a force transducer for 10min at 10%, 15%, and 20% of the maximum bite force. During each session, bite force, perceived muscle pain and electromyographic activity were continuously assessed. Data analyses were performed by means of cross-correlation and periodogram analyses. RESULTS: During sustained static contractions, different contraction patterns of jaw elevator muscles could be identified. These included a coactivation pattern, a substitution pattern, and several intermediate situations between coactivation and substitution. CONCLUSIONS: The findings support the concept that the masticatory muscles are functionally heterogeneous and provide evidence that the neuromuscular strategies used by the masticatory system to perform sustained static contractions differ between individuals. SIGNIFICANCE: Individual neuromuscular strategies might play a role in the development of masticatory muscle pain conditions.

OBJECTIVE: Previous reports indicated that between-muscle substitution of active motor unit pools can be found in a variety of synergist muscles, including shoulder and leg muscles, but little information is available for the masticatory muscles. We hypothesized that, during a prolonged clenching effort performed at low- to moderate-bite force levels, a substitution pattern of activity can be found also in the masseter and anterior temporal muscles. METHODS: Ten healthy volunteers were recruited and were asked to clench unilaterally on a force transducer for 10min at 10%, 15%, and 20% of the maximum bite force. During each session, bite force, perceived muscle pain and electromyographic activity were continuously assessed. Data analyses were performed by means of cross-correlation and periodogram analyses. RESULTS: During sustained static contractions, different contraction patterns of jaw elevator muscles could be identified. These included a coactivation pattern, a substitution pattern, and several intermediate situations between coactivation and substitution. CONCLUSIONS: The findings support the concept that the masticatory muscles are functionally heterogeneous and provide evidence that the neuromuscular strategies used by the masticatory system to perform sustained static contractions differ between individuals. SIGNIFICANCE: Individual neuromuscular strategies might play a role in the development of masticatory muscle pain conditions.

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13 citations in Scopus®
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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:04 Faculty of Medicine > Center for Dental Medicine > Clinic for Masticatory Disorders and Complete Dentures, Geriatric and Special Care Dentistry
Dewey Decimal Classification:610 Medicine & health
Language:English
Date:2009
Deposited On:13 Mar 2009 14:28
Last Modified:05 Apr 2016 12:55
Publisher:Elsevier
ISSN:1388-2457
Publisher DOI:10.1016/j.clinph.2008.10.004
Related URLs:http://www.sciencedirect.com/science/journal/13882457 (Publisher)
PubMed ID:19026593
Permanent URL: http://doi.org/10.5167/uzh-11981

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