[Bend over and bend the calves with weights] mainly exercises the buttocks. Lie on your hands and knees, with your knees at 90 degrees, and tie a sandbag to your ankles (be careful not to put too much weight on it). First straighten one leg back, approximately parallel to the ground, and then bend the knee hard to 90 degrees. Repeat after restore. 3 sets of 20 reps per side. Note that movements must always be controlled and cannot be "thrown".
