Effects of firing statistics on the mean frequency of EMG and VMG signals

The mean frequency of EMG and VMG signals has been used as an indicator for muscle fatigue. The muscle fatigue is a complex process, which involves both central nerve system (CNS) and local muscle activities. Here, the authors adopt a multichannel linear dynamic model for EMG and VMG signal generations under voluntary contractions. The mean frequency of EMG and VMG signals under the different firing statistics was calculated. The results show that the mean frequency of VMG signal is more sensitive to the mean firing rate of the innervation than that of corresponding EMG signal, suggesting that the VMG signal might be more sensitive to CNS fatigue.