## 2 Materials and Methods
### Measures  
Anthropometric Characteristics. The body mass, body height and body composition were assessed prior to the standardized warm-up. The body height was measured using a fixed stadiometer while the body mass was measured at nearest of 0.1 kg using a weight scale (Seca 769; Hamburg, Germany). The body composition was tested using a skinkold caliper ([PERSON]; Cambridge Scientific Industries, Cambridge, MD, USA). The body fat percentage was calculated using the 3-site methods of [PERSON] et al. [16]. Ultrasound assessments. Non-invasive skeletal muscle ultrasound images were collected from the participant's right thigh. Prior to image collections, all anatomical locations of interest were identified using standardized landmarks for the VL. The landmark for the VL was identified along its longitudinal distance at 50% from the proximal insertion of the muscle. The length of the VL encompassed the distance from the lateral condyle of the tibia to the most prominent point of the greater trochanter of the femur. VL measurement required the participants to lay on their side on the examination table for a minimum of 15 min before images were collected. The same investigator performed all landmark measurements for each participant. A 12 MHz linear probe scanning head (Echo Wave 2, Telemed Ultrasound Medical System, Milan, Italy) was coated with water soluble transmission gel to optimize the spatial resolution and used to collect all ultrasound images. The probe was positioned on the surface of the skin without depressing the dermal layer and the view mode (gain = 50 dB; image depth = 5 cm) was used to take panoramic pictures of the VL. During the measurements, the participants were asked to relax their leg muscles and maintain the left lateral decubitus position. Legs were positioned together, with a 10\({}^{\circ}\) bend angle in the knees [17]. All images were collected and transferred to a personal computer. All ultrasound images were taken and analyzed by the same technician. The muscle thickness and PA were quantified in still images using the measuring features of the ultrasound device. The muscle thickness was determined as the distance between the subcutaneous adipose tissue-muscle interface and the intermuscular interface, and the PA was determined as the angle between the echoes of the deep aponeurosis of the muscle and the echoes from interspaces among the fascicles. The fascicle length was calculated from MT and PA using the following equation [8]:  
\[\text{FL}=\text{MT}\times\text{SIN}(\text{PA})^{-1}\]  
The intra-class correlation coefficients (ICCs) were 0.96 (SEM = 0.63 mm), 0.93 (SEM = 1.1\({}^{\circ}\)) and 0.96 (SEM = 8.0 mm) for PMT, PA and FL, respectively. Strength and power assessments. A countermovement jump test (CMJ) was performed using a contact mat (Globus Ergo Jump, Codogne, Italy) to measure the flight time. The jump height was calculated using the following equation [18]: 9.81 \(\times\) flight time\({}^{2}\)/8. The participants performed two jumps with a 3-min rest between each jump. They were required to keep their hands on their hips while jumping and were asked to maximize their jump height. The intraclass coefficient calculated for the CMJ was 0.96 (SEM = 100.3 W). An isometric squat test (ISQ) was performed using an adjustable rack that permitted fixation of the bar at appropriate height while the participants were standing on a force plate (Kistler, Winterthur, Switzerland, 500 Hz). The isometric parallel squat was performed with knee and hips at the same height. The participants were required to perform two maximal 6-s isometric muscle actions with a 3-min recovery time between each attempt. The peak force was measured and the peak rate of force development was calculated using a 20-ms window (pRFD20), as previously described by [PERSON], [PERSON], [PERSON], [PERSON], and [PERSON] [19]. The intraclass coefficients were 0.85 (SEM = 130.7 N) and 0.51 (SEM = 1010.3 N s\({}^{-1}\)) for ISQ and pRFD20, respectively.