Ankle sprains are so common that there are few people who have not turned their ankle. It might have happened by stepping into a hole while running, coming down with a rebound in basketball, stepping off a curb. Almost anything will produce a sprain. Eighty-five percent of all ankle injuries in sports are sprains.

The ankle would seem to be a solid, stable structure with one important exception: the lip of the bowl formed by the tibia and fibula is not uniform. On the outside of the ankle it protrudes farther down toward the foot than on the inside, and the outside lip is thicker than the inside, as well.The result of this uneven construction is that the ankle bone is more easily able to roll toward the inside of the joint, where the bowl is shallower, than to the outside. When that natural inclination is encouraged by some outside agent - a hole in the sidewalk or coming down off-balance - too often the ligaments on the outside of the ankle cannot take the stress of the violent roll inward, and they stretch, strain or tear. This results in a sharp pain, swelling, and drawn-out discomfort known as an ankle sprain.

The most important thing you can do is apply compression to the injured area - more important than getting off the ankle, more important than icing, more important than elevation. Compressing the ankle immediately will prevent more discomfort than anything else you can do.

Compression involves more than simply wrapping the ankle with an elastic bandage. The problem with such a wrap is that it provides pressure only over the ankle bones, which stick out farther than the rest of the ankle. The soft hollow areas surrounding the protruding ankle knobs are not affected by the wrap at all. Such wrapping does little good and should be avoided.

A simple and effective way to counteract swelling is to take any soft pliable material - a sock, an old T-shirt, disposable diapers - and cut and fold it into the shape of a horseshoe. Place this "horseshoe" around the ankle knob with the curved part down. Then, wrap the entire ankle, horseshoe and all, with an elastic bandage. This wrapping applies pressure to all areas of the ankle, not just the ankle bone.

Compression does not have to be hard. Compression against the ankle knob does nothing for the sprain. Be sure to make the pressure firm and equal throughout the area by using the "horseshoe" technique. Keep it on for the first 24 hours.

If ice is available, use that, too. Cold will constrict blood vessels and other soft tissue to keep swelling to a minimum. Whatever you do, don't use heat on the injury - at least not at first. Wait at least 24 hours and better still, up to 72 hours before applying heat.

At least 24 hours after the injury, with swelling stabilized and pain no longer increasing, it's time to increase the circulation around the joint. Such blood flow will leach out some of the accumulated fluid and debris from the bleeding and promote healing.

One way is by using contract baths. These baths, alternating warm and cold, can help increase blood supply by first constricting the blood vessels with cold, then opening them with warmth, draining the area. This can be easily done at home using two containers such as the bathtub or a waste basket. The water need not be too warm (about 100 degrees or a little above normal body temperature). While the ankle is in the warm water keep moving it. One way is by writing the alphabet with your big toe, in letters as large as you can tolerate.

Try four minutes in the warm water to one minute in the cold (use ice cubes in the water). Alternate from one to another for 20 minutes every day.

The longer you baby the ankle, the longer it will take to recuperate. Therefore, let pain be your guide, but attempt to walk on it. So long as you are not in pain, you're not harming your ankle.

- Alton Thygerson is a professor of health sciences at Brigham Young University.