If the person does not exercise frequently before and suddenly exercises with high intensity, this is basically an over-exercise, the heart and lungs cannot keep up, the blood is concentrated in the limbs and lungs, the body consumes a lot of energy and energy in replenishing oxygen to the muscles, which will cause gastrointestinal ischemia, and the vagus nerve in the stomach will send a signal that “it is not appropriate to eat at this moment”; in addition In addition, it may lead to a rapid rise in short-term body temperature and inactivation of some enzymes in the body, thus causing short-term stomach discomfort.