Muscle coactivation: a generalized or localized motor control strategy?

Abstract

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.

Keywords: EMG; elbow; knee; motor control; muscle cocontraction.