## 2 Materials and Methods
### Traditional and Accentuated Eccentric Loading Testing Sessions  
The first of three testing sessions took place 72 h following the 1 RM and familiarization session. The order of the remaining sessions was randomized for each participant and each separated by 72 h. Once participants arrived for the testing sessions, their body mass was collected before completing the general and dynamic warm-up previously described. Participants then completed a self-selected number of squats with an empty 20 kg barbell before performing three back squat repetitions with the 5 kg weight releasers that fell off after the first repetition. This served as a last familiarization trial and allowed the investigators to confirm the weight releaser length for each participant. The warm-up protocol then required the participants to perform back squat sets using 30% (five repetitions), 50% (three repetitions), and 70% (three repetitions) of their 1 RM. The participants had two minutes of rest between warm-up sets. During the AEL sessions, a \"walk-out\" with the load of the first testing set (i.e., 50% 1 RM and weight releaser load) was performed to acclimatize them to the feeling of the potential weight releaser swing as well as the maximal or supramaximal load that they would be eccentrically lowering during the squat. After the warm-up, three back squat repetitions were performed using 50, 60, 70, and 80% of the participants' 1 RM. The sets were performed in a progressive order while three minutes of rest was provided between each set. Readers should note that the weight releasers were used on the first repetition of each back squat set during the AEL conditions but not during the subsequent repetitions. In addition, the participants were asked to complete the eccentric phase of each back squat repetition using their normal squatting tempo but were encouraged to perform the concentric phase with maximal intent (i.e., as fast as possible). Briefly, each set required participants to pick up the barbell from the squat stands, step back onto the force platform, and stand motionless for at least one second before receiving a countdown of \"3, 2, 1, Go!\". After the countdown, the participants performed the back squat set with maximal effort before re-racking the barbell on the squat stands. While the same load was used throughout each repetition during the sets performed during the TRAD session, the loading conditions differed during the AEL sessions. For example, 100 or 110% of the participants' 1 RM was used during the eccentric (braking) phase of the first repetition of each back squat set during the AEL-MAX and AEL-SUPRA sessions, respectively; however, the concentric loads were equivalent to those performed during the TRAD session [11; 12]. As an example of this loading method, the AEL-SUPRA session had participants perform the braking phase of the first repetition with 50% 1 RM on the barbell and 60% 1 RM added by the weight releasers on either end of the barbell (i.e., 30% 1 RM on each weight releaser), totaling 110% 1 RM. During the first squat repetition, the weight releaser load (i.e., 60% 1 RM) would fall off at the bottom of the squat before the participant performed the concentric phase and following two repetitions with only 50% 1 RM. Thus, the braking phase of the first repetition within the set was performed with a supramaximal load while the propulsion phase of the first repetition and the braking and propulsion phases of the following two repetitions were performed with only the barbell load.