Table 1.

The protocol of Muscle Thickness and Cross-Sectional area of rectus femoris measure using musculoskeletal ultrasound.

	Description
Muscle to assess	Rectus femoris of quadriceps
Patient position	Patient lying supine, hips and knees in a neutral position
Patient condition	The patient had to maintain the same position for at least 30 min before the assessment, measuring the muscle in a relaxed state and before any functional testing.
Ultrasound and probe characteristics	B-mode ultrasound, 12 MHz, with a 5 cm-linear transducer probe.
Probe position	The probe in neutral/perpendicular to the skin, with a generous amount of transmission gel, maintaining the minimal pressure possible between the transducer and the skin.
Anatomical landmarks	Proximal landmark: greater trochanter. Distal landmark: proximal border of the patella.
Measuring point	The middle point of distance between anatomical landmarks, marking this point with a demographic pencil.
Measurements procedures	With the transducer probe in the measuring point. The measure of Muscle Thickness: -The most extensive distance from superficial aponeurosis to deep aponeurosis (distance in mm). The measure of cross-sectional area: -The circumference of the muscle, manually drawing with the ultrasound cursor (quadrat area in cm2).
Final value	The investigator repeated each measurement three times and used the mean value.