Estimation of muscle electrical activity synchronisation degree

The question of whether the activity of separate muscle motor units is synchronised or whether the synchronisation appears with muscle load changes has always been one is most important questions in electromyography. However, so far there has been no unambiguous answer. The simultaneity of the appearance of electromyogram (EMG) pulses or the coincidence of frequencies of signals coming at the same time from different electrodes fixed on the skin surface or inserted into the muscle is usually considered to be the criterion of synchronisation. Changes in muscle load increase the frequency of the pulse appearance and the number of different motor units involved. This effect makes the revelation of the channel potential's identity much more complex. This paper analyses the synchronisation degree of the signals in EMG channels based on the criteria and quantitative measures developed in nonlinear dynamics.