The effect of intramuscular fat on the large strain mechanical properties of skeletal muscle as measured by anisotropic MRE

Intramuscular fat (IMF) increases with BMI and age, but it is unknown how it affects skeletal muscle viscoelastic properties, despite the key role skeletal muscle mechanical properties play in our capacity to move. We studied the effects of IMF on the anisotropic mechanical properties under large deformation of the calf muscles in healthy and obese participants, using an advanced approach incorporating diffusion tensor imaging data into magnetic resonance elastography reconstructions. Results show that intramuscular fat had no significant effect on muscle shear moduli, but stretching or shortening muscle altered the parallel and/or perpendicular stiffness and viscosity of some muscles.