Estimation of the number of motor unit action potentials in the surface electromyogram

The number of motor unit action potentials (MUAP) appearing in the surface electromyogram (EMG) offers potentially valuable information about both motor unit recruitment and firing rates. In this paper, we seek to evaluate several different surface EMG processing parameters to estimate the number of MUAPs present in standard surface EMG records. Based on the morphological features of surface MUAPs, a series of surface EMG signals were simulated. The relationships between the number of MUAPs in the simulated surface EMG and the different kinds of surface EMG processing parameters were derived to evaluate their performance for MUAP number estimation. The results indicate that the parameters based on turns, spikes or zero-crossings counting are suitable for MUAP number estimation.