Tummy pain after sit-ups usually has the following three causes: First, after the effective stimulation of the abdominal muscles after exercise, the body’s anaerobic glycolysis is excessive triggering the accumulation of lactic acid. Usually sit-ups are an anaerobic exercise, so there will be a lot of glycolysis, starting the glycoisomeric pathway. This will secrete too much lactic acid, and the accumulation of lactic acid will trigger soreness, especially abdominal pain. Second, such as the practice of sit-ups, the force of the wrong muscle, did not play a local weight loss and fat loss effect, but will be the corresponding excessive stretching of the medial abdominal muscles, lateral abdominal muscles, transverse abdominal muscles and oblique abdominal muscles triggered by abdominal muscle pain and other symptoms. Third, practice sit-ups such as too much time, or cause skeletal muscle rhabdomyolysis when there is too much creatine kinase, will also trigger stomach aches and pains.