Table 3.

The program for conventional trunk exercise group

Exercise	Instruction and progress	Volume
Week 1,2
Sit–up–1	Standard sit‐up	40 s × 3 sets
Sit–up–2	Sit‐up with trunk rotation	40 s × 3 sets
Back extension–1	Raising the upper body and legs	40 s × 3 sets
Week 3,4
Sit–up–1	Increase time	50 s × 3 sets
Sit–up–2	Increase time	50 s × 3 sets
Back extension–1	Increase set	40 s × 4 sets
Back extension–2	Raising the arm and contralateral leg	50 s × 2 sets
Week 5,6
Sit–up–1	Increase time	60 s × 3 sets
Sit–up–2	Raising the single side (A) Right side (B) Left side	A, B: 25 s × 3 sets
Back extension–1	No change	40 s × 4 sets
Back extension–2	No change	50 s × 2 sets
Week 7,8
Sit–up–1	Hip bend 60°off the floor and leg was straight	50 s × 3 sets
Sit–up–2	Increase time	A, B: 30 s × 3 sets
Back extension–1	Increase time	45 s × 4 sets
Back extension–2	Increase time	55 s × 2 sets
Week 9,10,11,12
Sit–up–1	Increase time	60 s × 3 sets
Sit–up–2	Increase set	A, B: 30 s × 4 sets
Back extension–1	Increase time	50 s × 3 sets
Back extension–2	Increase time	60 s × 3 sets