Estimation of the conduction velocity of muscle action potentials using phase and impulse response function techniques

Two new techniques are described for calculating the conduction velocity of action potentials in muscle fibres from surface EMG recordings in human subjects. In the first method the conduction velocity is determined from the impulse response function calculated from the two EMG signals. The peak of this function onsists of a single peak located at the delay between the signals. The velocity probability density distribution is then estimated from this impulse response function. The mode of this distribution occurred at 5 m s−1. The second technique uses the phase part of the frequency response function relating the two EMG signals to determine the conduction velocity. These two new approaches overcome some of the limitations associated with estimating conduction velocity from the maximum absolute value of the cross-correlation function, and provide additional information about the conduction velocity.