1, it is not recommended to do sit-ups on an empty stomach, which will cause the risk of small intestinal infarction. Usually do sit-ups two hours after dinner.

2, sit-ups (English: sit-ups), is a common fitness exercise, mainly to exercise the muscles of the waist and abdomen. The preparation action is to lie on the floor, bend your knees to relax your back muscles and spine, straighten your legs together, and then lift your body, but your hips can't leave the ground, and your feet can't move or lift until your body is 90 degrees from the bottom, and then repeat. Now sit-ups generally require hands to hold your head, and your forehead touches your knees after getting up. There are also those whose arms swing straight up.