Abdominal pain after sit-ups may be a normal physiological phenomenon, but it cannot be ruled out that it is caused by muscle strain, intestinal cramps, etc., and the cause should be identified in a timely manner. 1. Normal physiological phenomenon: usually when sit-ups, the abdominal muscles may be stimulated to a certain extent, at this time, the body may normally produce lactic acid, if the excessive activity leads to excessive lactic acid secretion, there may be pain, soreness and other feelings. Generally speaking, this is a normal physiological phenomenon. 2. Muscle strain: If before doing sit-ups, improper preparation activities, lack of concentration and other reasons may cause muscle strain, resulting in abdominal pain after sit-ups. 3. Intestinal spasm: it may be that when doing sit-ups, it affects the gastrointestinal tract, leading to gastrointestinal dysfunction or intestinal spasm. Generally there is no relationship with the abdomen and waist exertion, it is the inside of the intestinal pain, may be wandering, sometimes pain, sometimes no pain. Abdominal pain after sit-ups, there may be other reasons, if you exclude the physiological causes, you should consult a doctor to clarify the specific causes, and if necessary, the appropriate treatment.