Because the blood flow of lower limbs increases during running, the blood vessels of skeletal muscles dilate, and a large amount of blood is stored in veins (veins contain a large amount of blood as volume vessels), and the feet are soaked just after running, and the capillaries of lower limbs further dilate, which may lead to edema of lower limbs. In addition, it may lead to hypotension (venous blood cannot return to the heart).