Shear Wave Velocity of Vastus Lateralis

Shear wave velocity of the right VL was measured by an ultrasound SWE apparatus (Aixplorer version 12, Supersonic Imagine, Aix-en-Provence, France) with a linear array probe (SL10-2), as previously reported (7 (link)). Briefly, the ultrasound probe was placed at 50% of the thigh length and aligned in the plane of the VL fascicles so that several fascicles were identified across the B-mode image, at the following three knee joint angles: (i) the knee fully extended in the supine position; (ii) the knee flexed at 90° in the seated position; and (iii) the knee passively (supported by the examiner) fully flexed in the seated position. The SWE measurements were performed in this order. The participants were instructed to relax completely throughout the measurements. In each position, three measurements were performed (i.e., three images were acquired). The SWE data were analyzed using the software included with the ultrasound apparatus to calculate SWV over the region of interest, which was as large as possible, in VL without aponeurosis or subcutaneous adipose tissue. It was confirmed that no pixel in the region of interest reached the saturation limit of SWV (16.3 m/s). For each position, the average of three measurements was used for further analyses. All measurements and analyses of the SWE data were performed by an examiner with more than 5 years of experience.