DEAR DR. DONOHUE: I play tennis only in the fall and winter, and my problem is tennis elbow. I can almost predict it will happen again this year. A friend has told me about sound-wave treatment. How does it work? Is it reliable? – B.C.

ANSWER: You’re speaking of ESWT – extracorporeal shock-wave therapy. It’s a gadget that directs sound waves at the painful site, a little bit like the sound waves used to break up kidney stones. In theory, the waves increase circulation, break up any scar tissue that might be adding to the pain and stimulate healing. Sometimes the treatment is a bit painful, so the doctor might have to numb the area first.

There are staunch proponents of ESWT, but there are staunch opponents, too. The opponents say it doesn’t work, and there is a recent study that backs them up.

It won’t hurt you, but it is expensive. If you can afford it or your insurance covers it, then you’ve nothing to lose but money. If the money is coming out of your own pocket, I would hold off until more studies are done.

DEAR DR. DONOHUE: I have a very studious 10-year-old boy who hates to exercise and who’s not good at sports. He reads all the time and is putting on weight. How much exercise should he do a day? What kind of exercise is good for a kid who’s not very gifted athletically? – C.C.

ANSWER: The Centers for Disease Control and Prevention recommends that school-age children get 60 minutes of moderate to vigorous physical activity daily. Weight gain among inactive children is reaching epidemic levels.

He doesn’t have to be good at sports to exercise. Many noncompetitive activities will keep him in shape. Fast walking is an example. Naturally, the boy has to start out modestly. He should not try for a full hour at the start.

Has his dad ever tried teaching him a sport? Maybe with some instruction and practice, he’ll find one he likes.

The booklet on aerobics, fitness and abdominal exercises gives guidance on how stay fit and how to achieve a flat belly for the young and old. Readers can order a copy by writing: Dr. Donohue – No. 1301, Box 536475, Orlando, FL 32853-6475. Enclose a check or money order (no cash) for $4.75 U.S./$6.75 Can. with the recipient’s printed name and address. Please allow four weeks for delivery.

DEAR DR. DONOHUE: I am a 54-year-old man who has lifted weights for many years. Two weeks ago, while doing biceps curls, I heard a popping noise and got a terrific pain in my right biceps. I dropped the weights. When I looked at my arm, it had an unnatural bulge in the front of the upper arm, and it hurt. The next day I saw a doctor, who told me I had ruptured a tendon. He said to leave it alone. I have lost strength in that arm, and it still hurts. What’s your opinion? – R.K.

ANSWER: The biceps muscle on the front of the upper arm has two actions. It bends the elbow. It also supinates the forearm and hand. If you let your arm dangle at your side with the knuckles of your hand forward, supination is the motion made when you turn your hand so the palm faces forward. The biceps is the arm’s most powerful supinator.

You have described tearing the biceps tendon from its attachment very clearly. The bulge you see in the upper arm is the retracted biceps muscle. Without a tendon holding it in place, the biceps bunches up.

A ruptured biceps tendon doesn’t interfere with elbow-bending too much. It greatly affects supination, however. I would get the opinion of an orthopedic surgeon, and if surgery is suggested, go for it.

DEAR DR. DONOHUE: Are squats harmful to the knees? – P.G.

ANSWER: Not if you do them right. Squats are a knee-bending exercise done with a barbell supported on the shoulders behind the neck. You don’t have to bend the knees so that the buttocks touch the heels. Bend only to the point where the thighs are parallel to the ground. That gives the thigh muscles plenty of exercise and spares the knees.

DEAR DR. DONOHUE: I am a 55-year-old female. Six years ago, I suffered a severe depression and was told that I had a chemical imbalance. My doctor prescribed Zoloft. I have been taking it ever since, and the doctor says I should take it for the rest of my life because I have had four episodes of depression. I would like to stop taking it, but I’m afraid the depression will return. I am also afraid of what this medication might be doing to my body. Is its long-term use dangerous? – L.K.

ANSWER: After having one major depression, a person has a 50 percent chance of having a second one. After two depressions, there’s a 70 percent chance of suffering a relapse. After three, there’s a 90 percent chance that another episode will occur. Relapses often last longer and are often more severe than the first episode. Most doctors, therefore, advise people who have had three major depressions to stay on antidepressants for life.

There are many, many such people taking these medicines for years and years, and the majority tolerate them quite well. You have more to fear from not taking the medicine than you do from taking it.

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.