DEAR DR. DONOHUE: I worked my own dairy farm for 50 years. I’ve been retired for five years. My wife says I’m turning to fat. I was quite muscular. Is there any proof that at my age, 73, exercise can turn my fat back to muscle? I am also interested in exercising for my heart. Will it do me any good to take it up now? I should have started when I was a young man. – R.K.

ANSWER: You did start exercising as a young man. You farmed. It’s hard to find an exercise that’s as strenuous as that. I don’t know what you’ve been doing in the past five retirement years, but it’s never too late to begin an exercise program.

Muscles don’t turn into fat. With disuse, they shrink and become weaker. Body weight stays the same, and that’s because people don’t cut back on their calories. Fat fills the void created by muscle shrinkage. Inactive people lose about 7 pounds of muscle weight for every 10 years of inactivity after age 30. You weren’t inactive. If your muscles have shrunk, they’ve only shrunk for the past five years of retirement. You can get them back. Muscle strength increases at any age if muscles are exercised.

As far as heart health goes, I’m not in a position to estimate how well farming contributes to it. Heart health depends on aerobic exercise, the kind of exercise where the heart beats faster for a prolonged period of time – 20 to 30 minutes. Jogging, running, swimming and biking are examples of exercise that keeps the heart healthy and blood pressure low. You can begin this kind of exercise at any age so long as your doctor approves. Aerobic exercise can stress the heart, so older people must know the status of their hearts before they attempt doing it.

DEAR DR. DONOHUE: Almost every day I run 16 kilometers (10 miles). I have been doing this for a number of years, and I could do it with ease. In the past three months, however, I find the run more difficult. In fact, often I can’t make that 16K distance. What do you think has gone wrong? – B.M.

ANSWER: A 16-kilometer (10 mile) run is quite an endurance feat. You can’t run that distance day after day without taking a break. It’s too much exercise. Running that much three days in a row leaves your muscles depleted of glycogen – stored muscle sugar, the fuel for muscle action.

Take a week or two of rest right now. When you resume running, start with lesser distances and give yourself at least a day’s break between long runs.

What’s your diet like? I know it’s currently unfashionable to promote carbohydrates, but distance runners need them to replete muscles’ glycogen stores. You should have lots of carbohydrates – pastas, breads, potatoes.

DEAR DR. DONOHUE: Does lifting a 5-pound weight 10 times accomplish the same thing as lifting a 50-pound weight once? – B.C.

ANSWER: No, it doesn’t.

Lifting heavy weights with few repetitions – the number of times the weight is lifted consecutively – builds strength.

Lifting light weights many times builds endurance.

The two are not the same.

DEAR DR. DONOHUE: I don’t mean this as a foolish question, but I have always wondered about the exercise involved in sexual relations. Is it really exercise? Is it dangerous for people with heart disease? I have heard that it can cause heart attacks. – M.H.

ANSWER: Sexual relations make the heart beat faster and raise blood pressure. Its energy cost is equivalent to climbing one flight of stairs.

It’s dangerous for people with heart conditions if their doctors have told them to abstain. That’s hardly ever the case. People with heart attacks are not routinely forbidden to have sex.

As for the heart-attack stories, if they’re true, they are exceedingly rare.

DEAR DR. DONOHUE: Maybe you could explain to me what a subtalar fusion is. My husband had this surgery done about 30 years ago. Now he has great pain in his foot at the site of the operation, and the pain doesn’t let up. He takes Mobic, but that helps very little.

Can you recommend something that will give him a night’s sleep? The pain is there 24 hours a day, seven days a week.

The doctor recommended New Balance sneakers and an elastic wrap around his foot and ankle, but they help for only a short while. – R.C.

ANSWER: The talus is a foot bone. It sits on top of the heel bone and has a thick, sturdy upward projection that’s sandwiched between the two lower leg bones to form the ankle joint.

Bone fusions weld bones together to provide joint stability.

A subtalar fusion unites the talus with the heel bone beneath it. It’s done for fractures, for arthritis or for pain that occurs when the bones aren’t properly aligned.

Screws are sometimes used in fusion. Loosening of the screw could cause pain at this late date. However, you and your husband might be barking up the wrong tree by blaming the long-ago surgery for being the cause of his present pain. Something completely unrelated to surgery might be going on. He needs to contact an orthopedic doctor to uncover the source of pain and to get rid of it, if possible. The only other suggestion I can give is for him to ask for stronger pain medicine until that cause is found.

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

Only subscribers are eligible to post comments. Please subscribe or to participate in the conversation. Here’s why.

Use the form below to reset your password. When you've submitted your account email, we will send an email with a reset code.