Extensional Wave-Propagation Characteristics in Striated Muscle

Abstract

The real part of the complex dynamic modulus for frequencies 50–10 000 Hz was derived from viscoelastic wave-propagation constants in whole frog skeletal muscle, in order to provide a material function characteristic of the dynamic longitudinal viscoelastic behavior of resting skeletal muscle in the higher-frequency range. The method of measuring the phase velocity and attenuation coefficient of longitudinal waves propagated along the longitudinal axis of thin muscles is described. The results showed that there were significant viscoelastic effects between 50 and 5000 Hz with some leveling off above 5000 Hz, as indicated by the frequency dependence of the wave propagation constants. The relaxation time spectrum derived from the dynamic modulus-frequency function showed that about half of the relaxation times were less than 1 msec. The results were generally consistent with other studies based on the time course of stress relaxation and on the relationship between sinusoidal stress and strain.