The NEMS of spastic muscles with a frequency of 100 to 350 Hz result in a fair reduction of spastic tone that lasted for hour. The neurophysiological rationale for the effectiveness of NEMS activation of the spastic muscles may be two fold. First it could lead to fatigue of the peripheral system. It is theorized that either neuromuscular junction fatigue or a possible depletion of Ca++ release at post synaptic binding sites might have been responsible for the reduction in muscle tension.

A second neurophysiological mechanism by which NEMS of the spastic muscle might affect a reduction of muscle tone rests in antidromic activation of alpha motor neuron axon. Antidromic propogation may provide a spinal level response that could lead to longer lasting modulation of spastic tone. With each voluntary and stimulated action potential, the alpha motor neurone activates the motor unit and excites a pool of Renshaw cells through recurrent collaterals. The Renshaw cells inhibit the alpha motor neurons of the activated pool and motor neurons of synergistic muscles.