Razieh Nasrabadi, Nosratollah Hedayatpour, Ali Sharifnezad, Zahra Izanloo

Abstract

Change in  propagation velocity of of electomyographic signals has been reported after fatiguing exercise and as well as  after eccentric exercise induce muscle fiber damage, most likely due to change in membrane permeability of muscle fibers.  Both mean power frequency (MPF ) and conduction velocity (CV) has been used to estimate change in  propagation velocity of of electomyographic signals. Thus, it is expected that eccentric exercise of quadriceps muscle result in significant changes in both MPF and CV after eccnteric exercise.  The aim of the study was to investigate MPF and CV of the VMO muscle  before and after eccentric exercise. Multichannel surface EMG signals were concurrently recorded from the right VMO muscles of 15 healthy men during sustained isometric contractions at 50% of the maximal force. Maximal voluntary force significantly reduced after eccentric exercise with respect to the baseline (P<0.004).  MPF and CV of EMG signals significantly  decreased over time during the sustained contraction after eccentric exercise(P<0.05). Moreover, change in MPF and CV of EMG signals was significantly correlated (r= %73.8) . The result indicate that MPF of EMG signals can be used as an index to estimate change in propagation velocity of EMG in the injured muscle.