Introduction: In this study we examine the repeatability of measuring muscle shear modulus using ultrasound shear-wave elastography between trials and between days, and the association between shear modulus and contraction intensity over a wide range of intensities.
Methods: Shear modulus of the biceps brachii was determined using ultrasound shear-wave elastography during static elbow flexion (up to 60% of maximal contraction) in healthy young adults.
Results: The correspondence of shear modulus was confirmed in phantoms between the manufacturer-calibrated values and the shear-wave elastography values. The intraclass correlation coefficient of muscle shear modulus was high: 0.978 between trials and 0.948 between days. Shear modulus increased linearly with elbow flexion torque across contraction intensity, and its slope was associated negatively with muscle strength.
Conclusions: Muscle shear modulus measured with ultrasound shear-wave elastography may be useful for inferring muscle stiffness across a wide range of contraction intensity. In addition, it has high repeatability between trials and between days.
Keywords: biceps brachii; elastography; electromyography; muscle stiffness; muscle tone.
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