Muscle coactivation: A generalized or localized motor control strategy?


  • Laura A. Frey-Law PhD, PT,

    Corresponding author
    1. Department of Physical Therapy and Rehabilitation Science, Carver College of Medicine, Iowa City, Iowa, USA
    2. Virtual Soldier Research, Center for Computer-Aided Design, College of Engineering, University of Iowa, Iowa City, Iowa
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  • Keith G. Avin MS, DPT

    1. Department of Physical Medicine and Rehabilitation, McGowan Institute for Regenerative Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
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  • This study was supported in part by grants from the National Institutes of Health (NRSA F31 AR056175 to K.G.A., K12 HD055931 to L.F.L., and K01AR056134 to L.F.L.), the American Physical Therapy Association (to K.G.A.), and the United States Council for Automotive Research, Southfield, Michigan.


Introduction: We examined generalized versus joint-specific influences on muscle coactivation. Methods: Muscle coactivation was assessed during maximal isometric and isokinetic knee and elbow joint extension moments in 48 healthy subjects (27 men). Local (joint-specific) and generalized (person-specific) contributions were examined using a combination of statistical tests, including regression with generalized estimating equations (GEEs), exploratory factor analysis, and cluster analysis. Results: GEEs produced similar significant coefficients for gender and joint; contraction type and test condition (angle or velocity) were not significant. Factor analysis indicated 2 joint-based factors, and cluster analysis indicated 2 groups of individuals, those with and without elevated coactivation at the knee and elbow. Women exhibited greater coactivation at both joints, but no consistent influences of angle or velocity were observed at either joint. Conclusion Muscle coactivation is a neuromuscular control response determined by local, joint-specific, and generalized, individual-specific influences. Muscle Nerve 48: 578–585, 2013