Characterization of tissue stiffness of the infraspinatus, erector spinae, and gastrocnemius muscle using ultrasound shear wave elastography and superficial mechanical deformation.

The aim of this study was to compare measurement methods of tissue stiffness using ultrasound shear wave elastography (SWE) and superficial mechanical deformation (MyotonPRO) in the infraspinatus, erector spinae, and gastrocnemius muscles. Thirty healthy volunteers were assessed during rest, 40% and 80% maximum voluntary isometric contraction (MVIC). Correlation of the two methods in the three muscle regions was significant (r = 0.23-0.71, p < .05), and strongest in the gastrocnemius. MyotonPRO reliability was excellent (ICC > 0.93), and demonstrated ability to discriminate between the three levels of muscle contraction. SWE demonstrated good reliability in the resting condition (ICC > 0.88), but lower during the 2 MVIC conditions. The utility of SWE during isometric contraction may be limited due to the inability to discriminate between 40% and 80% MVIC.