With any sprain, strain or bruise there is some bleeding into the underlying tissues. This may cause swelling and pain which can delay healing.
Ice treatment is most commonly used for these acute injuries. If you have a recent injury (within the last 48 hours), especially if swelling is a problem, you should be using ice treatment.
Ice packs can help minimize swelling around the injury because ice is a vaso-constrictor (it causes the blood vessels to narrow) and it limits internal bleeding at the injury site. Icing the injury site early and regularly will help minimize swelling which will in turn help to reduce the pain. It is recommended that ice is only applied for 10-15 minutes every hour.
Ice treatments may also be used for chronic conditions, such as repetitive strain or overuse injuries. In this case, ice the injured area after activity to help control inflammation. Never ice a chronic injury before activity.
Heat is generally used for chronic injuries (>3 months old) or injuries that have no inflammation or swelling. Aching, tight or stiff muscles or joints is ideal for the use of heat therapy.
Athletes with chronic pain or injuries may use heat therapy before exercise to increase the elasticity of joint connective tissues and to stimulate blood flow. Heat can also help relax tight muscles or muscle spasms.
Do not use heat treatments after activity, and do not use heat after an acute injury. This will increase bleeding and make the problem worse. When using heat treatments, be very careful to use a moderate heat for a limited time (10-20 minutes) to avoid burns. Never leave heating pads or towels on for extended periods of time, or while sleeping.