Simulation linking EMG power spectra to recruitment and rate coding.

Abstract For muscles, a graded increase in motor unit size, with the number of fibres in the motor units forming an arithmetic progression, leads to a model consistent with experimental findings. This model has been combined with electrical signal characteristics of activated muscle fibres and the signal attenuation due to the spread of the electrical signal to bipolar surface electrodes. For the biceps brachii this electromechanical model links motor unit recruitment, rate coding and frequency shifts in the surface EMG power spectra. Derived data suggests that motor unit degeneration results in an abnormally large high frequency EMG component.