QUESTION: It seems that my granddaughter, age 6, has inherited the problem of weak ankles that plagued her father (my son) and myself in our younger years. The slightest provocation causes her ankles to turn to the side, causing pain. Right now, she is wearing high sneakers in the hope that they will add enough support for the ankles. Do you recommend strengthening exercises? If so, what type? - C.D.

ANSWER: First off, consider her shoes. She needs shoes with strong heel counters to keep the feet and ankles from wobbling. And for the same reason the soles should be firm.I would suggest taping of the ankles, but that might be a bit impractical for a 6-year-old. Exercises are definitely in order. Strengthening the muscles and ligaments of the adjacent muscles would provide a natural bracing. Here are a few exercises that might be appropriate for a child.

Have her trace circles with the balls of her feet, first in a clockwise, then counter-clockwise direction. Another similar and even fun exercise for her might be sole tracing of outlines of letters of the alphabet. You can have her walk alternately on toes, then on her heels, a few minutes of each, a few times a day.

You should see some benefit from a combination of exercise and attention to proper footwear.

QUESTION: I purchased an expensive exercise bike last winter to help get in shape. I had no trouble scheduling sessions, and everything was working as planned except for one problem. The more I rode, the worse my tailbone hurt, even to the point of hurting all day when sitting down or getting up. When I quit riding the bike, the problem cleared up. Can you tell me what's wrong? - Mrs. S.B.

ANSWER: The narrow seats you find on most bikes just are not adapted to the female anatomy as much as they are to the male's. The female pelvis is wider, so it needs a wider bike seat to distribute body weight more comfortably. Investing in a new bike seat should be the answer for you.

How the seat is adjusted is also important in avoiding tailbone pain. For a woman, the tip of the seat should be parallel to the ground or pointed slightly downward. Seats should also be adjusted to one's height. With either pedal in the bottom position, that leg should be straight. A new seat and a few adjustments will, I'm sure, get you back with your fitness program.

FOR L.P.: Your Parkinson's disease support group will find many worthwhile books to help your education program. The Parkinson's Disease Foundation people tell me they provide a listing of new books about the disease. You can contact them at 650 West 168th St., New York, NY 10032. Enclose a stamped, self-addressed envelope for return mail.

Dr. Donohue's Booklet No. 11 shows you how to avoid and take care of foot problems. Send your request to Dr. Donohue/No. 11, P.O. Box 830, Gibbstown, NJ 08027-9909. Enclose a long, self-addressed, stamped envelope and $2.

Dr. Donohue welcomes reader mail but regrets that, due to the tremendous volume received daily, he is unable to answer individual letters. Readers' questions are incorporated in his column whenever possible.