Heat compresses and ice packs are both used to treat sports injuries. But which one is right for your particular problem? The answer depends on when you were injured, the nature of the injury and the effect you'd like the treatment to have on that injury.

Ice is the treatment of choice for injuries occurring within the last 48 hours that involve swelling. A sprained ankle is a perfect example. Let's say you twist your ankle in aerobics class. Almost immediately, you notice that your ankle starts to swell. This is your body's natural response to injury. Unfortunately, your body can overreact, and the swelling can become as much of a problem as the original injury. Ice, a natural vasoconstrictor, lessens the blood flow to the area and temporarily numbs it. The combined effect reduces swelling and pain.

The natural anti-inflammatory property of ice can be useful to treat older injuries (often described as "chronic") that are worsened or irritated by using the joint or muscle. For example, a tennis player whose elbow or shoulder throbs after a match may want to ice it after her match. A runner whose knee hurts after a long run may benefit from ice, as well. In these cases, ice should be applied to reduce inflammation only after the athletic activity. If ice is applied before the event, it may make matters worse by reducing the blood flow to the injured body part just as it's being pressed into service.

In contrast, heat therapy is used to combat older injuries where no swelling is present. Sore, aching, stiff muscles or joints can often benefit from heat before exercise. Heat increases blood flow in the area of application and increases the elasticity of connective tissues. Warmer, more relaxed muscles and joints will have a better range of motion. This translates into enhanced performance and less likelihood of further injury. Heat should never be applied immediately after an athletic activity because it may encourage inflammation.