It is not suitable to work out after a fever, because the body’s defense system will work intensively during a fever, because the fever itself is a defense response of the body to disease, and its purpose is to remove pathogenic bacteria, such as viruses or bacteria. During fever, in addition to an increase in body temperature, white blood cells increase, which, if exercised at this time, can increase the heat in the body and cause a disruption of immune regulation. In addition, the body’s function is relatively reduced in patients with fever, so even less intense exercise will put the patient under a greater physiological load, and immunosuppression will occur in the gut after exercise, which in turn will further reduce the body’s resistance. Therefore, the best choice is to rest when you have a fever and wait until the fever is completely healed before you work out.