There are two basic types of injuries: acute and chronic. Acute pain occurs when an injury is recent and can be attributed to some activity, and swelling can usually appear. Chronic pain occurs when an injury develops slowly over a period of time. It is subtle in nature, and is often referred to as “overuse injury.”
Ice is the best form of treatment for acute injuries because it slows the inflammation response in the body and slows the pain response as well. It works by narrowing the blood vessels in the area and therefore limits bleeding in that region. Ten to 15 minutes of icing at a time is sufficient. Wrap the area in a towel for comfort. Allow the skin to return to normal temperature before repeating. Do this as often as you feel is warranted for up to three days.
Chronic injuries should be iced as well, but only when the icing follows an activity. This prevents re-irritation of the area. I don’t recommend icing a chronic injury before activity.
Heat is best with chronic injuries or injuries that have no inflammation or swelling. Sore, stiff, nagging muscles or joints are best treated with heat. Injuries of this nature are often heated prior to activity to increase flexibility and blood flow. Safely apply heat to an injury 15 to 20 minutes at a time and use enough layers between your skin and the heating source to prevent burns. Moist heat (i.e. wet towels) works best.
Because some injuries can be serious, you should see your doctor or physiotherapist if your injury does not improve (or gets worse) within 48 hours.