DEAR DR. DONOHUE: I am a marathon runner and have been for years. Five years ago, I suffered a mild stroke. It has affected my equilibrium. Doctors tell me that nothing can be done. I am now a jogger, and jog three to four miles four times a week. Is there anything you could advise to improve my balance? — Anon.

ANSWER: Balance is a complicated process that involves the eyes, the inner ear, sensors (proprioceptors) in joints, tendons, muscles and skin that relay to the brain information on body position, and finally the brain itself. Muscle strength also is important. With age, unless a concerted effort is made to keep muscles strong, they shrink, weaken and are unable to hold the body in balance. Furthermore, since we are an overmedicated population, medicines often can be the reason for balance loss.

Older people have many conditions that cause them to totter and fall. Your stroke is an example. However, the brain can transfer functions lost in one damaged region to other regions and regain much function. You are not without hope.

One simple leg-muscle strengthening exercise is simply rising from a chair with arms folded across the chest. When a person becomes adept, the exercise has to be done many times in a row and several times a day. If you’re up to it, and it sounds like you are, exercising with weights is a greater stimulus for strength. Squats are done with a barbell resting on the shoulders while bending the knees until the thighs are parallel to the floor.

Balance exercises can revive nerve pathways that have gotten rusty through the years from disuse. These exercises are best done in a doorway so you can quickly stabilize yourself if you become wobbly.

The first exercise is standing on one foot for as long as you can. You alternate feet and perform a series of repetitions of the exercise.

An advanced balance exercise is standing on one foot while swinging the other foot in front of the body like a pendulum. Again, you alternate feet and perform as many swings as you can.

DEAR DR. DONOHUE: I am a black woman with a 13-year-old son who will be in high school next year. He has his heart set on playing football. His father has sickle cell trait, and I had the boy checked. He has it, too. I heard that sickle cell trait can cause death during hard exercise. Should we allow our son to play football? — L.N.

ANSWER: Two genes, one from the mother and one from the father, lead to sickle cell anemia, a serious condition. Sickle cell trait indicates that a child has inherited only one sickle cell gene, either from the mother or father. People with the trait have normal, active and long lives.

In a small number of people, sickle cell trait led to sudden death when the affected person attempted lengthy, strenuous exercise and became overheated. This happens rarely and usually to an untrained person. The Army became aware of the relationship of sudden death to sickle cell trait in recruits who were not used to such vigorous exertion. What happens is a breakdown of muscles with release of materials that shut the kidneys down. It’s called rhabdomyolysis. The Army revised its training protocols to protect recruits from getting dehydrated and overheated. The problem was solved. If the Army can deal with the situation, your son’s high school ought to be able to deal with it too. You should explain to the coach the implications of sickle cell trait.

DEAR DR. DONOHUE: I am an 82-year-old woman and have a sagging neck. Folds of skin hang down, and it looks awful. Do you know any exercises that could firm my neck? — E.W.

ANSWER: I know some neck muscle exercises, but they won’t do a thing for sagging skin. Furthermore, they’re not safe for a woman of your age.

The only treatment that can fix such a problem is surgery. Are you sure you want to consider that?

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.