Pain on the right side of the stomach while running may be caused by gastrointestinal dysfunction, improper diet, and respiratory rhythm disorders. 1. Gastrointestinal dysfunction: if you run on a full stomach or an empty stomach, it may cause gastrointestinal spasm, which may lead to pain on the right side of the stomach. 2. Improper diet: if you eat improperly before running, eat some spicy, stimulating, greasy and other indigestible food, it may also cause gastrointestinal stimulation during running, which may lead to pain on the right side of the stomach during running. 3. Disordered breathing rhythm: If you don’t adjust your breathing well, your breathing rhythm is disordered, and your tissues can’t get enough oxygen, which may lead to spasm of diaphragm and pain on the right side of the stomach while running. Pain on the right side of the stomach while running may also be that the patient himself has chronic appendicitis, chronic hepatitis and other diseases. If you have pain on the right side of the stomach while running and the symptoms are not relieved after sufficient rest, it is recommended that you consult a doctor in time, make a clear diagnosis and follow the doctor’s instructions to standardize the treatment.