The main reasons for running with a particularly red face include vasodilation, increased aerobic metabolism, and a transient deficiency in oxygen partial pressure. 1. Vascular expansion: after running, blood circulation will increase and blood flow speed will also increase, so there will be vascular expansion. Facial blood vessels and nerves are more abundant, and the skin of the face is relatively thin, so it will lead to a particularly red running face. 2. Increased aerobic metabolism: the aerobic metabolism of the human body will increase when running, and the heat produced by the body will also increase, accompanied by sweating, body temperature rise and other phenomena, which will lead to a particularly red running face. 3. Oxygen partial pressure transient insufficiency: when running, the human lung movement increases, arterial blood oxygen saturation will also decrease, there is a transient insufficiency of oxygen partial pressure, which leads to running face especially red. Running face especially red for many reasons, is a normal physiological phenomenon, if accompanied by obvious discomfort, it is recommended to go to the hospital in a timely manner, improve the examination under the guidance of the doctor to deal with, so as to avoid adverse consequences.