[Supine Crunch] mainly exercises the upper abdominal muscles. Lie on your back, place your hands by your ears, roll up your upper body until your upper back leaves the lying board, at a constant speed, roll up and exhale, lie flat and inhale. Do 4 sets of 20 times every other day. Note: The lower back cannot be arched to use inertia to complete the movement. viaPhysical Sculptor-Zhang Kun
