Changes in the myoelectric signal (MES) power spectra during dynamic contractions

Power spectra of surface myoelectric signals (MES) have been estimated during dynamic contractions of the biceps brachii. The effect of applied torque, velocity of contraction and muscle length have been studied with respect to median frequency and total spectral power. The results of the investigation carried out thus far can be summarised as follows: (1) The median frequency is observed to vary with the applied torque and the muscle length but not with the velocity of contraction. (2) The expected dependence of the MES power with the applied torque, velocity and muscle length was confirmed. These results suggest that the power spectrum could be used to reveal changes in the electrophysiological characteristics of a muscle during dynamic contractions as is the case with static contractions.