When to apply Cold or Heat

A general guideline to follow is to use cold in the early stage of most injuries then use heat later in certain circumstances.

The most common injuries in sports are strains. A strain is an injury to either a muscle or a tendon (fibrous cords of tissue that connect muscle to bone). The muscle fibres stretch and tear, resulting in internal bleeding and swelling. Depending on the severity of the injury, a strain may be a simple overstretch of the muscle or tendon, or it can result from a partial or complete tear.Second to strains are bruising (or contusions). Contusions are usually caused by a hard blow to a muscle crushing underlying muscle fibres and connective tissue without breaking the skin. The result is torn blood vessels which cause internal bleeding. Sometimes a pool of blood collects within damaged tissue, forming a swollen lump over the injury (hematoma).  

A sprain is an injury to the ligament (a band of fibrous tissue that connects two or more bones at a joint) of a joint. Sprains occur when a joint is forced beyond its normal range of motion and the ligament stretches and/or tears. Swelling is usually great and the pain can be severe. An important question is whether to use heat or cold in treating the injury. Remember “PRICE” as a guide to treating acute injuries:

Protect the injured part from further injury
Restthe injury
Compression firmly (but not too tightly)
Elevate the injury to decrease bleeding.

How Cold Works

Using cold with gentle compression after you suffer an injury helps stop internal bleeding in the tissue, relieve pain, reduce muscle spasms, cool deep tissues, lower metabolic activity, and reduce swelling and inflammation. Cooling can produce dramatic drops in tissue swelling because cold initially constricts the walls of blood vessels and decreases blood flow to the injured tissue. Compression also decreases the blood flow to an injured body part. Compared to heat, cold works better to decrease swelling and discomfort. Cold’s pain-killing effect is caused by its “deadening” of nerve activity; patients who use cold therapy on injuries tend to require much less pain medication. Cold decreases muscle spasms by making muscles less sensitive to being stretched, and, like heat, cold can be used to treat low-back pain. As an aside, research suggests that cold works better for individuals who have had back pain for more than 14 days, while heat may be more effective for those with more recent pain. Cold eases pain and helps restore motion.

When to Apply Cold Therapy

The earlier the cold is started the better – ideally within the first 48 hours. You should apply cooling therapy as soon as possible after the injury and continue using it until the swelling goes away.

How Heat Works

The application of superficial heat to your body can improve the flexibility of your tendons and ligaments, reduce muscle spasms, alleviate pain, elevate blood flow and boost metabolism. Exactly how heat relieves pain is not exactly known, although some believe that it inactivates nerve fibres which can force muscles into irritating spasms, and that it may cause the release of endorphins (powerful body chemicals which block pain transmission). Heat does help tissue rebuild by increasing blood flow and tissue repair. Increased blood flow occurs in heated parts of the body because heat tends to relax the walls of blood vessels. That’s why sports doctors recommend that you do not heat up already inflamed joints.

When to Use Heat

Heat therapy can be used during the repair stage of an injury when new tissue is being formed. This is usually 48 to 72 hours after the initial injury (once the risk of internal bleeding is minimal), and after cold has been used and swelling is reduced. That’s because heat increases the blood flow to the injury area, and that can increase swelling. Heat in any form should not be applied to an acute injury or where discoloration or swelling is present. While heat shouldn’t be used to treat an acute injury, it can be used to decrease joint stiffness. Although heat can reduce muscle spasms after a back injury (which is usually muscular), heat should not be used on ligament injuries like sprained ankles or strained joints.


Please Note

Some injuries can be self-treated whilst others require prompt medical attention. You should seek advice from a health professional if: the injury causes severe pain, swelling, or numbness; you can't tolerate weight on the area; the pain or dull ache of an old injury is accompanied by increased swelling or joint abnormality or instability.