## 2 Materials and Methods
### Study Design, Tasks and Measurement Procedure  
Strength and flexibility for all trunk, hip, knee and ankle muscle groups, along with postural control outcomes, were measured in a random order. This protocol was used, as recent studies report that body sway did not increase after a whole-body fatigue protocol [32]. Trunk, hip, knee and ankle muscle strength were evaluated by performing maximal voluntary contractions (MVC) using specific custom-made dynamometers (S2P Ltd., Science to practice, Ljubljana, Slovenia) [33]. As previously reported, the dynamometer proved to be both a reliable and valid (ICC \(\geq\) 0.95) muscle strength assessment tool [34; 35]. For trunk muscle strength assessments, participants were positioned standing hip-wide on the dynamometers' anti-slip platform. Participants were positioned facing the dynamometers' sensor for trunk flexion muscle strength assessment, while they turned their back to the sensor when assessing the trunk extension muscle strength. The lower support was positioned below the iliac crist, and the upper support was at shoulder height. Both supports were individually adjusted to the participants' heights. The lever-arm length was expressed as the distance between the lower and upper support. To avoid compensating mechanisms, participants' pelvises were stabilized with a fixating strap, and they were asked to stand with feet flat on the platform (Figure 1). by strong verbal encouragement. Each repetition was hold for approximately 5 s before allowing participants a 30-second break before the next MVC. The best of three consecutive repetitions was considered for further analysis [7]. Additionally, the Nordic hamstring exercise was performed as it requires trunk muscle activation and elicits a high activation of the hamstrings [37]. Passive trunk, hip, knee and ankle ranges of motion (RoM) were measured by the same three investigators, one performing the movement, the other reading the measurements and the third noting the results. Participants were positioned supine while prominent anatomical landmarks of the lower extremities were marked. Measurements were provided using a digital inclinometer providing measurements of 0.01\({}^{\circ}\) accuracy/interval (Baseline Digital Inclinometer, Fabrication Enterprises, Inc., White Plains, NY, USA) [38; 39] and a standard 31.7 cm long and 4.5 cm wide goniometer made of clear plastic with 1\({}^{\circ}\) increments and 360\({}^{\circ}\) scale. The participants' pelvises were stabilized during all hip measurements to prevent pelvic rotation. Hip flexion and ankle plantar flexion were tested with both knees extended and knees flexed. All ankle measurements were performed with the axis of movement on the lateral malleolus, with one arm of the goniometer following the base of the thumb and the other arm aligned with the shin [40]. No warm-up or test trials were performed prior to assessment. One repetition of each movement was performed based on previous recommendations suggesting that one RoM measurement was as reliable as the mean of repeated measurements [41]. Body sway and symmetry were evaluated on bilateral force platforms (9260 AA, Kistler, Winterthur, Switzerland). Participants were assessed barefoot with hands positioned on their hips. After adopting a comfortable position, they were asked to remain quiet during the 30-s single-leg stance with eyes open. Assessment was performed on both legs with center of pressure parameters such as velocity, amplitude and direction defined as main outcome measures. Standing symmetry was expressed in percentage (%) and evaluated with hand on their hips in standing, semi-squat and full squat positions, respectively. Symmetry indexes were determined based on the \(<\)10% inter-limb symmetry threshold [42]. Data for MVC, RoM and stability measures were collected into pre-prepared spreadsheets and transcribed into MS Excel Software (Version 2019, Microsoft, Redmond, Washington, DC, USA).