Sprained foot 3 days after the time to soak feet, because at this time the blood vessels have basically closed, there will be no significant outward blood seepage, to increase local venous reflux, to promote the local exuded blood can be effectively metabolized in a timely manner, and can reduce the local injury caused by inflammatory edema, relieve swelling and pain and unfavorable activity related symptoms. If you soak your feet before, it will lead to vasodilatation of the injured blood vessels and increase the amount of blood leakage, which will lead to more obvious symptoms of local swelling and pain. Not all people start foot soaking on the 3rd day or so, and if there is still foot activity after the previous 3 days of injury, it can lead to further aggravation of the local injury and possibly further continuation of blood seepage. This will lead to further bleeding during the foot soak leading to more pronounced swelling. Therefore, the choice of 3 days to start foot soaking should be done only after the sprain with adequate external fixation of the foot and relaxation and rest.