Prone Buttocks Squeeze - Topic Overview This exercise strengthens the buttocks muscles, which support the back and help you lift with your legs. Lie flat on your stomach with your arms at your sides. Slowly tighten your buttocks muscles and hold the position (not your breath) for about 6 seconds. Relax slowly. Repeat 8 to 12 times. You may need to place a small pillow under your stomach for comfort.