Heat or Cold on Injury?

INJURY

What happens to the tissues after an injury?
When a runner "pulls a groin" or a tennis player "strains a tendon," the soft tissues in the area of pain are injured. Immediately after the injury, there are disrupted fibers of the affected muscle, tendon, and/or ligament. Additionally, the tiny blood vessels (capillaries) that normally supply blood and oxygen to these tissues are broken. The broken capillaries then leak varying amounts of blood and serum into the adjacent tissues. Therefore, soon after a soft tissue injury, localized swelling occurs. The injured tissues become painful and tender, both directly from the trauma to them and indirectly from the subsequent swelling. This leads to the stiffness, pain, and tenderness that so often accompany the inflammation of tendinitis, bursitis, as well as strain and sprain injuries. It should also be noted that even a bone injury (such as a fracture) is typically accompanied by injury to the nearby soft tissues.

So, what is best applied after the injury?
In a word, ICE.

The swelling and much of the inflammation that follows an injury is largely due to the leakage of blood from the ruptured capillaries. Therefore, cold applications with ice can help by causing the blood vessels to constrict (clamp down). This constriction of the blood vessels prevents further leakage of blood and serum and minimizes swelling and pain. The cold from an ice pack application also has an added benefit of providing pain relief.

In fact, the optimal management of an acute injury can easily be remembered using the acronym, RICE:

Rest (minimize movement of the injured body part)
Ice (apply a cold pack)
Compression (light pressure wrap to the affected body part can help minimize leakage of blood and swelling)
Elevation (raise the body part up so that the pressure from the blood and tissue swelling the affected area is reduced as the fluids drain from the area by gravity)

How does ice help after an injury and how might heat hurt?
As stated above, icing the injured tissues helps by limiting the leakage of blood and serum from the capillaries into the adjacent tissues. Ice also prevents swelling. In contrast, heating tissues causes the capillaries to widen. This widening can cause an increase in the leakage of blood from the capillaries and add to the swelling and pain. It is important to note that the blood that leaks into the tissues will later lead to inflammation, which slows the healing process.

What about recovery after the injury?
The days after an injury, when the tissues are healing, require a different approach from the immediate treatment. Now, the blood leakage from the injured capillaries has generally stopped because the capillaries have been naturally plugged by microscopic blood clots in the repair process. The blood that remains in the tissues needs to be reabsorbed by the body. At this time, heat applications can help, especially prior to recovery exercise workouts. The heat provides an additional benefit by relaxing the muscles of the injured area so that the workouts can occur as safely as possible. Frequently, immediately after a recovery workout, ice is applied so that leakage of serum and/or blood from any capillaries that are disrupted during the workout is minimized.