AN EQUILIBRIUM-POINT MODEL OF ELECTROMYOGRAPHIC PATTERNS DURING SINGLE-JOINT MOVEMENTS BASED ON EXPERIMENTALLY RECONSTRUCTED CONTROL SIGNALS

The purpose of this work has been to develop a model of electromyograp hic (EMG) patterns during single-joint movements based on a version of the equilibrium-point hypothesis, a method for experimental reconstru ction of the joint compliant characteristics, the dual-strategy hypoth esis, and a kinematic model of movement trajectory. EMG patterns are c onsidered emergent properties of hypothetical control patterns that ar e equally affected by the control signals and peripheral feedback refl ecting actual movement trajectory. A computer model generated the EMG patterns based on simulated movement kinematics and hypothetical contr ol signals derived from the reconstructed joint compliant characterist ics. The model predictions have been compared to published recordings of movement kinematics and EMG patterns in a variety of movement condi tions, including movements over different distances, at different spee ds, against different known inertial loads, and in conditions of possi ble unexpected decrease in the inertial load. Changes in task paramete rs within the model led to simulated EMG patterns qualitatively simila r to the experimentally recorded EMG patterns. The model's predictive power compares it favourably to the existing models of the EMG pattern s.