EMG to force processing III: Estimation of model parameters for the human triceps surae muscle and assessment of the accuracy by means of a torque plate

Abstract

The parameters of the active state and the series-elastic component of the Hill muscle model were estimated for the human calf muscles by means of a ‘torque plate’ on seven normal subjects. Together with the results of the calfergometer experiments (Part II) this yields the complete set of parameters for the EMG to force processor based on the Hill model (Part I). The accuracy of the processor was assessed by means of a set of severe test contractions in which the subjects tilted on one foot at various velocities (slow to as fast as possible). The mechanical work ∫ M ϕ ̇ dt and the integrated torque ∫ M d t were calculated for these contractions, M being the torque calculated by the EMG processor and ϕ the measured angular velocity. These values of the work and the integrated torque were compared to those obtained with the measured torque M m instead of M. The relative error, for positive work, negative work, and integrated torque was + 6.2% ± 14% (means ± s.d.). Data on the peak values of M – M m are also given.