Synchronous firing behaviour in human motor units

The purpose of this investigation was to determine under what conditions synchronous firing behavior would occur. A technique for the decomposition of the composite myoelectric signal was used to obtain individual motor unit action potential trains. The presence of synchronization was then determined from the statistical analysis of cross-interval firing histograms. Synchronous behavior was observed in all muscles examined, and tended to be greater in distal muscle groups. A mechanism termed the ´driving motor unit theory´ is proposed to explain the synchronous firing behavior.<>