## 2 Materials and Methods
### Measurements  
One repetition maximum--1 RMSQ  
The participants underwent one-repetition maximum (1 RM) testing for the free-weight squat following guidelines established by the National Strength and Conditioning Association [24]. The process started with a standardized warm-up including dynamic stretching and preparatory exercises. This was followed by a series of warm-up sets: five repetitions at approximately 50% of their estimated 1 RM, three repetitions at around 70% of 1 RM, and two repetitions at about 80% of 1 RM. Afterward, the participants attempted their 1 RM with progressively heavier weights. A research team member monitored their squat depth to ensure that the participants reached a parallel position (thighs parallel to the floor). The participants were permitted up to five attempts, with their highest successful lift recorded as their one-rep max (1 RM). Individualized load-velocity relationships  
A linear encoder was utilized to assess the mean velocity (MV) during free-weight back squats (GymAware (GYM), Kinetic Performance Technologies, Canberra, Australia). The participants carried out the half-squat exercise starting from an upright stance. They descended at a self-regulated average speed of approximately 0.50-0.70 m\(\cdot\)s\({}^{-1}\) until the thighs were parallel with the floor. Then, they immediately reversed the movement to ascend back to the upright position at their maximum intended velocity. Before the main exercise, the participants completed a standardized warm-up like that performed in the one-repetition maximum (1 RM) test. They then executed three repetitions at 30% of their baseline 1 RM, followed by three at 60%, two at 80%, and one at 90%. Earlier studies verified that GYM provides excellent reliability of MV measurements within the range of 40-90% of 1 RM [24]. The participants received verbal encouragement and velocity feedback to achieve maximal concentric velocity on each repetition. A three-minute rest period was allowed between each load. Only the quickest repetition achieved for each absolute load was retained for future analysis. Individualized load-velocity profiles were developed by plotting mean velocities (MVs) against their corresponding loads and applying a line of best fit. The MVs for 60% and 80% of the one-rep max (1 RM) were subsequently used to modify the training loads in the velocity-based training (VBT) groups. Drop jump--RSI index test  
In the DJ test, thevparticipants descended from a 30 cm box using their preferred leg, landed on a contact mat with both feet, and then jumped as high as possible. They were instructed to maximize their jump height while minimizing the time spent in contact with the mat during the transition from landing to jumping. Each participant completed the test three times, taking a 30 s rest between jumps, and the highest result was noted for further analysis. The reactive strength index was determined by calculating the flight time/contact time (in seconds) ratio. The highest score was used for analysis. The Countermovement Jump Test (CMI) was conducted following the Bosco protocol [25] using a contact platform (Just Jump, Probotics, USA). The participants were directed to place their hands on their hips and maintain an upright position as they dynamically lowered themselves to a depth of their choosing before jumping upward with maximal effort and landing with their knees fully extended. Each participant was allowed three attempts, with a passive rest period of 45 s between repetitions. The highest jump performance recorded from these attempts was used for subsequent analysis. 20 m Sprint Test (SPR20)  
The participants underwent a 20 m sprint test, which was timed using light gates (Witty; Microgate, Bolzano, Italy). After a designated warm-up that featured two submaximal efforts, each subject completed two trials. They began from a crouched position with their front foot positioned 0.5 m before the first timing gate, and they started voluntarily to eliminate reaction time.