1, twisting abdomen: lying on the ground, legs together, body straight forward, elbows bent, hands on the back of the head up and down. Then bend your right leg properly with your knees, and bend your left leg upward with your knees so that your calves, thighs and thighs are perpendicular to the ground respectively. While lifting the leg, lift the right upper body to the left front, so that the right shoulder is off the ground, the right elbow is as close to the left knee as possible, and the abdomen is compressed. Do it again after changing sides.

2, sit-ups: knees together, lying flat on the ground, waist and back fully extended on the ground, arms bent elbows, hands holding the head, shoulder blades leaning back, so that your arms lean on the ground as much as possible. While exhaling, push your abdomen and lift your upper body. When lifting, the chin is retracted, the arm swings forward slightly, so that the elbow touches the knee and the feet keep on the ground. Then lie down slowly, regain your posture and do it back and forth several times.

3. Lift your shoulders: Lie down in the preparation posture of sit-ups, knees together, legs at about 90 degrees, hands on your head, exhale, lift your back above, shoulders off the ground, and close your chin, but don't lift your upper body too much, let alone do it. Try to keep your back down, including your back and hips, and keep your feet off the ground. Use the muscles of your upper abdomen to complete the lift.