Evaluation of viscoelastic changes of the psoas major muscle after exercise using MR elastography

The shear modulus of the psoas major muscle (PM) after exercise has been evaluated using magnetic resonance elastography (MRE) previously, however, a separate evaluation of elasticity and viscosity has not been performed. We evaluate storage modulus representing elasticity and loss modulus representing viscosity of the PM using MRE after exercise in this study. Comparing the before and immediately after exercise, the loss modulus showed a greater rate of decrease than the storage modulus, suggesting that the loss modulus, which reflects viscosity, is more useful for detecting changes of muscle tissue immediately after exercise.