Abstract des Autors

In the present study, we attempted to reconstruct the surface myo-electric signals from monopolarly recorded motor unit action potentials (MUAPs), and to construct a method of analysis for extracting information from surface ME signals on the recruitment behavior among motor units. 1) The waveform of a single MUAP of a surface electrode recorded monopolarly consisted of three phases: first, a positive, second, a negative transient and, third, a positive phase except for the end-plate region. The appearance of each phase could be interpreted from the field potential in the volume conductor produced by conduction of action potentials from the end-plate to the myotendinous junction. 2) Waveforms of MUAPs indicated that the positive phase and the negative phase are the same in area. In surface ME signals, coincidence of the phase areas was observed. Therefore, it was inferred that all the motor units producing the interfered surface ME signal showed a tendency to coincide with respect to the area between the two phases. 3) The fact that MUAPs consisted of three phases during conduction means that the contribution potential for a recorded electrode changes according to the position of the action potential on the muscle fiber(s). Therefore, the potential of a surface myoelectric signal represents the sum of the contributed potentials from activated motor units. 4) The amplitude of surface ME potentials tended to be other than 0 V as tension increased. 5) Considering the reconstruction of a surface ME signal involving many activated motor units from the contribution potential, the surface ME potential depends on the number of recruited motor units with a different waveform, in addition to the magnitude of synchronization and grouping discharge among motor units. Verf.-Referat