Action essentials: Action 1: Sitting posture, elastic belt can be fixed on other objects. Hold elastic belt in both hands, lean forward to the maximum position, and then slowly return. Pay attention to keep your head and body in the same plane, and don't bow your head. Action 2: Sitting posture, elastic belt covers his feet and does sit-ups slowly. Elastic belt can also be fixed on the object behind the head of the body to increase the load and do sit-ups. Pay attention to exerting force on the back, and fix the upper limbs without exerting force. Function: It can strengthen the muscles of waist and abdomen. It can strengthen the protection of the spine and reduce pain such as low back pain.