Sit-ups can not do generally because of the core strength of the waist and abdomen is poor. Sit-ups rely on the contraction of the core muscles of the waist and abdomen, mainly including the waist of the psoas major muscle, lumbar square muscle, latissimus dorsi and other muscles, as well as the abdomen of the rectus abdominis, abdominal obliquity, abdominal obliquity and so on. So it is necessary to strengthen the exercise of these waist and abdominal muscles. Exercise lumbar core muscle groups can choose to do the big Yan Fei and other actions, the specific operation of the patient prone position, both lower limbs and upper limbs straightened and lifted, the head lifted, adhere to the 5 ~ 10 seconds, continue the above action can be. Exercise abdominal core muscle groups can do abdominal movements, specific operation for the patient lying on his back, double knee flexion, core tightening, lifting the upper body, slowly down, repeat the above action can be.