Chaos as a possible model of electromyographic activity

Grounds for the hypothesis that chaotic dynamics may underly the EMG are established and discussed. In order to test this hypothesis, investigations into the dynamics of the system driving the firing of motor units during a contraction have been carried out. They consist of: 1.) the construction of phase portraits; 2) correlation dimension analysis; and 3) calculation of dominant Lyapunov exponents. The results obtained from analysing real EMG data recorded from both normal and disordered subjects do not support the hypothesis that the EMG arises for a system having chaotic dynamics. As a result of this analysis, it is evident that the system driving motor unit firing during a contraction of the human muscle may not be proven to be chaotic, at least not with the techniques presently available. Simulation may still be better achieved using a model based upon statistics