The benefits of icing the knee after exercise mainly include rapid vasoconstriction, reducing edema and so on. The knee joint is an important weight-bearing joint of the lower limbs, and large sports or hard pulling, squatting and other weight-bearing actions will cause accelerated blood circulation around the knee joint, vasodilatation, and a large accumulation of acidic metabolites such as leukotrienes, oxygen free radicals, lactic acid and so on around the knee joint. Ice can quickly shrink local blood vessels, slow down the local inflammatory response and reduce joint swelling after exercise. Ice packs after exercise need to pay attention to the time window, ice packs generally do not exceed 72 hours, 72 hours after the relief period, capillary microcirculation reopened, the need to discharge metabolites, generally take the hot packs, to accelerate the local blood circulation; and prolonged post-exercise ice packs may lead to long-term spasm of the local vasculature, ischemia, accelerate the wear and tear of the joints, leading to premature aging of the joints.