Boarding service:
Lie on your back on the floor with your lower back close to the ground. Put your hands on your head and open your arms. Lift your legs and climb on the bike slowly. Exhale, lift your upper body, touch your left knee with your right elbow, hold your posture for 2 seconds, and then restore. Touch the right knee with the left elbow again, hold it for 2 seconds, and then slowly return to the starting position.
Traditional belly roll:
Lie on your back on the floor with your lower back close to the ground. Put your hands on your head and open your arms. Put your legs flat on the ground and bend your knees. The chin shrinks to the chest, contracts the abdominal muscles, exhales, lifts the upper body, keeps the lower back off the ground for 2 seconds, and then slowly returns to the starting position.
Arm sit-ups
Lie on your back, bend your knees and fix your feet. Wrap a towel around your neck from behind and pull one end with each hand. Tuck in your abdomen, lift your shoulders, slowly roll up your back, then slowly lean back, and continue to get up when you touch the ground. Repeat. If it's too difficult, lift your upper body off the ground.
Leg lifting and belly rolling:
Lie on your back on the floor with your lower back close to the ground. Put your hands on your head and open your arms. Raise your legs at 90 degrees to your upper body, cross your legs, and bend your knees slightly. Exhale, contract the abdominal muscles, lift the upper body, keep the lower back off the ground for 2 seconds, and then slowly return to the starting position. Keep your chin down to your chest.