2.5.1. Ultrasound Imaging Assessment
All ultrasound images were acquired by a certified ultrasound clinician blinded for group allocation of the participants. A Mindray M7 scanner (Mindray, Shenzhen, China) with a 4 cm, 10 MHz linear array transducer was used for ultrasound B-mode imaging of the lumbar region. Bilateral parasagittal images were acquired with the probe centered at 2 cm lateral to the middle of the L2–3 interspinous ligament [