2.4.1. Muscle thickness.
RA
All sonographic images were collected by a single-blinded experienced sonographic operator (HJY). We evaluated the thickness of the rectus abdominis (RA), external oblique (EO), internal oblique (IO), transverse abdominis (TrA), gluteus medius (GMed), and adductor longus (AL) on the dominant side. All muscles were investigated in both resting and contracted states. Ultrasound (US) images were acquired in B-mode with a portable US machine (MX7, Mindray, NJ) using a linear (3–12.8 MHz, L12-3RCs Transducer, Mindray, NJ) probe for abdominal muscles and a convex probe (1.4–5.1 MHz, C5-1s Transducer, Mindray, NJ) for GMed and AL.Transducer placement and participant position were determined based on previous studies.