Power changes of EEG signals associated with muscle fatigue: the root mean square analysis of EEG bands

The paper reports a research conducted to determine changes in the electrical activity of the contralateral motor cortex of the brain that drives the maximum voluntary contraction (MVC) of the right adductor pollicis muscle (APM) after fatigue. The power changes of EEG signals after muscle fatigue were computed. In twenty-five subjects, EEG signals from the left motor cortical area (C3, FC3) were recorded simultaneously with EMG signals from the right APM, before and after exercise-induced fatigue. The root mean square (RMS) of the EEG bands (alpha, beta, and gamma) was calculated to determine the power changes of the EEG signals after right APM fatigue. The mean RMS of the EEG bands were increased during MVC of the fatigued right APM compared to the RMS value during relaxation before fatigue (p<0.05). The RMS value was seen to be greatest in the beta band, and lowest in the gamma band. The observed increase in the RMS of EEG bands during MVC of the fatigued right APM suggest an increase in the EEG signal power, which could reflect an increase in energy needed by the motor cortex to perform MVC in fatigued muscles, which might give an indication of neural fatigue in the motor cortex.