DEAR DR. DONOHUE: All my life I have skied. I live in a place where everyone does it, both downhill and cross-country. When I was young, I suffered from frostbite on the index finger of my right hand. The town doctor thought I would lose the finger, but I didn’t. It is still numb.

My grandchildren, who live in the South, are visiting us, and I’d like to teach them how to ski. They’re willing to learn. Since my accident, I have been cautious about frostbite. Will you explain how to treat it properly? — M.K.

ANSWER: Prevention is the best treatment for frostbite. Common sense dictates that all skin should be covered, including the ears and the nose. Mittens provide better protection than gloves for hands and fingers, but they diminish hand and finger dexterity, so they’re not popular for all.

The earliest symptom of frostbite is pain. If anyone complains that a particular area hurts, get that person to a warm place immediately. If nothing is done, then the affected area becomes numb and the skin turns pale. Freezing is imminent. Ice crystals form in the tissues. They don’t cause great damage, but they do dehydrate adjacent cells. The real damage comes from a shutdown of blood to the frostbitten tissues.

Rapid rewarming is required, but don’t start rewarming if there’s a possibility that the frostbitten person will be exposed to cold again. Freezing after rewarming leads to greater damage than leaving the frostbitten area untreated for a time. Rewarming is done by immersing the frostbitten skin in a bath of warm water at a temperature between 100 and 104 F (37 to 40 C). Keep an eye on the water temperature and add more warm water as the bathwater temperature drops. It takes 20 to 40 minutes to thaw frozen tissue. For pain, aspirin is a good idea, and it also prevents clotting in the vessels supplying the cold-damaged skin. Stronger pain medicines might be needed. If blisters form, and they usually do, don’t puncture them. If they break, let the blister roof cover the open skin. If you have any misgivings about treating this kind of injury, don’t. Take the person to the hospital for expert treatment.

TO READERS: Information on beginning an exercise program is found in the booklet on Aerobics and Fitness. To order a copy, write: Dr. Donohue — No. 1301, Box 536475, Orlando, FL 32853-6475. Enclose a check or money order for $4.75 U.S./$6 Can. with the recipient’s printed name and address. Please allow four weeks for delivery.

DEAR DR. DONOHUE: My wife and I exercise together. She walks kind of fast, and I jog. Naturally, I cover more ground in a shorter time than she does. She says we both burn the same number of calories because she takes more time to cover the distance than I do. I say hooey. I say I burn more because I am exercising harder. Am I right or wrong? — B.W.

ANSWER: You’re right. Jogging burns more calories than walking. The faster you propel the body, the more calories you burn.

Do you weigh more than your wife? Body weight is another factor in calorie burning. It takes more energy to move a heavier body.

Don’t discourage your wife with this information. Walking is an excellent exercise, and she should be encouraged to continue. Not everyone can be a jogger.

DEAR DR. DONOHUE: I am a small, active female, concerned about osteoporosis. Is the following exercise good for osteoporosis? I stand with feet shoulder-width apart and keep my toes on the floor at all times. I bounce on alternate legs, like jogging in place, but my toes do not leave the floor. Is this useful? I do this for quite a while. — P.

ANSWER: Any weight-bearing exercise that stresses bone helps prevent osteoporosis. If one foot left the ground, the other foot and leg would be subject to a greater load. All the same, what you describe is at least partial weight-bearing and qualifies as osteoporosis exercise.

Dr. Donohue regrets that he is unable to answer individual letters, but he will incorporate them in his column whenever possible. Readers may write him or request an order form of available health newsletters at P.O. Box 536475, Orlando, FL 32853-6475. Readers may also order health newsletters from www.rbmamall.com.