Gravity shock

During the race, in order to supply sufficient nutrients and oxygen to the lower limbs that are exercising vigorously, the blood vessels of the legs and feet will relax as much as possible to help the blood flow. If you stop and stand immediately after the race, the blood will be trapped in the lower limbs due to the gravity of the center of the earth, causing anemia in the brain, resulting in pale faces, purple lips, and even fainting. This phenomenon is called "Gravity shock."