Often after a sports injury occurs, people are confused whether to use hot or cold compresses. The exact type of treatment needs to be determined by the type of injury. Acute injuries Acute injuries are often caused by sudden trauma (e.g., falls, sprains, and direct impacts) and are usually painful immediately. After an acute injury, local bleeding, inflammatory reaction, swelling and pain occur and must be controlled immediately. The immediate application of ice can lower the tissue temperature, reduce the metabolic rate and nerve conduction speed, and constrict the peripheral blood vessels to reduce swelling and pain. Depending on the size and depth of the injury, the duration of the ice pack is usually no more than 20 minutes. Every 2-3 hours can be reapplied. In the first 3-5 days of acute injury, once the bleeding is controlled and no further inflammation occurs, cold and hot compresses can be applied alternately. 10 minutes of cold compresses, followed by 10 minutes of direct hot compresses. The blood vessels are constricted during the cold compress and open up when converted to hot compress, and a large amount of blood flows into the injured area, which facilitates the repair of damaged tissues. Blood is an important factor in the supply of energy and nutrition, and has an important role in post-injury tissue repair. However, before alternating hot and cold packs, it is important to ensure that the injury is no longer bleeding locally. Chronic injuries Chronic injuries usually do not have a sudden trauma, but rather a slow onset after a long period of time due to repeated strain and overuse. Of course, chronic injuries can also be the result of untreated or improperly treated acute injuries. Heat treatment is usually applied for about 15-20 minutes, using a hot bottle, hot towel, hot massage or commercially available heat packs. The use of a hot bottle or the like requires wrapping a towel or clothing around it to prevent thermal burns. Hot packs are often used after chronic injuries to help relieve muscle tension, reduce pain, increase the elasticity of ligaments and tendons, and increase local blood supply. Applying heat to a chronic injury before exercise can help warm up the body and increase tissue flexibility and suppleness. If the acute attack of chronic injury, sports training (including post-operative rehabilitation in) after local swelling is not adapted to the use of cold compresses, can help reduce swelling. Acute reaction control, only after the application of hot compresses. Note: 1, not all chronic injuries to use heat, such as acute attacks are still the first use of ice; 2, not all acute injuries to use ice, early swelling, pain control can be changed to heat; 3, the choice of ice and heat should be based on the situation, should be carried out under the guidance of a doctor or rehabilitation teacher.