The progressive bodyweight squat program
The progressive bodyweight squat protocol consisted of 10 levels of squats from A to J, as described in supplementary During the familiarization sessions, all participants began with level C for the first set. If they could correctly complete 10 repetitions for double leg squat on four sets at level C in two consecutive training sessions, they could advance to level D. For single leg squat, participants had to perform 5 repetitions per side for single leg squat on four sets at level F in two consecutive training sessions to advance to level G. For example, participants who began with level C were required to perform six sets of bodyweight squats, including 12 repetitions for double leg squats at level A, 10 repetitions for double leg squats at level B, and four sets of double leg squats at level C (8 repetitions per set). In total, during an exercise session, they were required to complete the following: 12 (A)/10 (B)/8 (C)/8 (C)/8 (C)/8 (C)/8 (C). From the first training session in the formal intervention (week 3), participants gradually increased to 12 (E)/10 (F)/8 (G)/8 (G)/8 (G)/8 (G) after achieving 12 repetitions of level E, 10 repetitions of level F, and 4 sets of 8 repetitions of level G in that session (4 repetitions per side). In the next session, they aimed to finish 12 (E)/10 (F)/10 (G)/10 (G)/10 (G)/10 (G) (5 repetitions per side). If participants could perform 12 (E)/10 (F)/10 (G)/10 (G)/10 (G)/10 (G) in two consecutive sessions, they could progress to level H. Participants who began with 12 (F)/10 (G)/8 (H)/8 (H)/8 (H)/8 (H) followed the same pattern to progress throughout the 6-week training. When participants could not complete 8 repetitions for double leg squats or 4 repetitions on each side for single leg squats at each level, the progression ended, and they began again at the previous level. An example is shown in Table Bodyweight squat progression.Note: Repetitions × Sets = R × S; 1–6 represents each participant; E: Lunge, F: Bulgarian single leg squat, G: Skating squat; the table shows the training volume and movement level (A–J) completed by the 6 participants in the bodyweight squat group in the first four training sessions;