A new technique for measuring muscle fiber conduction velocities in full interference patterns

The motor unit potential shape, mainly its duration and frequency spectra, and the EMG IP crispiness and its frequency spectra are affected by the muscle fiber conduction velocities (MFCVs). Present techniques are somewhat deficient in that they are not adaptable to measure MFCVs continuously and intramuscularly in the presence of interference patterns, and to do so without interfering with the ongoing muscular activity. In this study a cross-correlation with averaging correlograms technique is presented. An EMG needle electrode, with two recording surfaces 1 cm apart, continuously record two channels of EMG activity which is analog-to-digital converted. Contiguous segments of the signals are cross-correlated, the evolved correlograms are averaged together, averaging-out the time-unlocked noise, and averaging-in a peak that represent the average time it takes the EMG signal to propagate from one recording surface to the other. From the distance between these two recording surfaces and the above calculated propagation time the MFCVs can be computed and monitored intramuscularly either in weak or in strong, in isometric or isotonic contractions. But for the fact that a needle is introduced, there is no interference with the muscle electrical activity. It is expected that this technique may add to EMG diagnosis of neuromuscular disorders, will be used to monitor muscular fatigue and applied in normalizing EMG spectra, conditioning them for a better use in diagnostic electromyography.