1. Lie prone on a flat bench, with your hips at the end of the bench, your legs straight, your toes off the ground, and your arms grasping the top of the bench.

2. Squeeze the muscles behind the hips and legs and straighten the legs to the same height as the hips. This is the starting position; Lift the left leg backward, and the left leg is higher than the right leg; Then put down your left leg and lift your right leg backwards.