DEAR DR. DONOHUE: I have never seen what is the best time to eat after exercise – right away or hours later? There’s lots of information about when to eat before exercise, but I can find any about eating after exercise. Is there a best time or doesn’t it make a difference? – L.C.

ANSWER: If you’re really into bodybuilding, then the time to eat after exercise does make a difference.

After heavy exercise, protein synthesis is at a high level. The correct timing of protein intake, therefore, is the time when you can increase the synthesis of muscle protein. Eating protein as soon as possible after exercise takes advantage of this phenomenon.

A similar story can be told for carbohydrates. After strenuous exercise, muscles are nearly depleted of glycogen, their stored carbohydrate fuel. By eating when muscles are most avid for glycogen, you provide muscles with an opportunity to store more of it than they normally do. This is called supercompensation.

That gives you two reasons for eating shortly after exercise.

DEAR DR. DONOHUE: I am a 67-year-old male who was jogging until a few years ago. It seemed to be affecting my knees badly, so I began to speed walk. I do so at a speed of 5.2 miles an hour for 30 minutes.

In snowy and icy weather, I run up and down the basement stairs for 30 minutes.

My doctor said running up and down the steps is actually better than speed walking. Is he correct?

ANSWER: In what way does he mean it’s better for you?

For burning calories?

For heart health?

For lowering cholesterol?

And by “speed walking” do you mean the kind of walking where one foot is always on the ground and where the knee of the foot striking the ground is kept straight until that leg is behind the body? Or do you just mean fast walking? Maybe I’m making a big deal out of the difference, and perhaps I don’t need to. At any rate, walking at that speed, a mile in less than 12 minutes, is a very good clip and burns many calories.

Climbing stairs is rigorous work. Going up the stairs means you’re fighting gravity with each step. Going down the stairs means leg muscles are tensing in such a way to prevent you from falling. Many considerations have to be factored in: the height of each stair, the incline of ascent, your speed and, of course, your body weight. Charts I consulted, however, give stair climbing the edge when it comes to calorie burning.

Either exercise stresses your heart. If you want to make a comparison between the two, count your pulse immediately upon finishing each exercise. The one that raises your pulse rate higher is the one that gives the heart a greater workout.

This doesn’t have to be an either-or thing. You can do both. Do the stair climbing in the winter and the fast walking in the milder months. Or alternate the workouts daily throughout the year. You exercise different muscles, and you bring variety to your program.

DEAR DR. DONOHUE: I am a 68-year-old man and in generally good health. I am 5 feet 11 inches tall, weight 205 pounds and have a 49-inch chest, 17-inch arms and 19-inch neck. However, I cannot build up my calves.

What exercises do you suggest for helping me with this problem? – T.R.

ANSWER: Your measurements are impressive. Are you Teddy Roosevelt in his best days?

Most find building calf muscles a difficult chore. The standard calf exercise is the rise-on-toes. Stand on a bottom step with a weighted barbell behind your neck and supported by your shoulders. The heels of your feet should be off the step. Rise on your toes and then lower yourself so your heels are below the step. When you do eight to 12 repetitions, change the position of your feet. Point the toes outward and repeat 12 repetitions. Then point the toes inward and do 12 more repetitions. You can take a break between each set.

DEAR DR. DONOHUE: Our 14-year-old grandson is 6 feet tall and has thick brown hair with noticeable gray in it. He also has some acne on his face. He is embarrassed by both. Can you give some advice? – S.R.

ANSWER: Gray hair starts to appear in whites between the ages of 25 and 43. By 50, half are gray or markedly graying. Blacks experience the change slightly later, and Asians, slightly sooner. Graying occurs when melanocytes – cells that produce the pigment melanin – are no longer making it and imparting it to the growing hair.

Age 14 qualifies, without a doubt, as premature graying. He could have inherited the gene that turns off melanin production. Or there might not be any explanation why it has happened; it just did.

In a few instances, illness turns the hair gray. Pernicious anemia and thyroid gland troubles can do it. An athletic, 6-foot-tall 14-year-old is not likely to have an unrecognized illness. The only answer to hiding gray hair is to color it. I’d like to convince him that gray hair looks distinguished, even on a 14-year-old.

Fourteen is an age when acne is practically expected for a boy. The surge of male hormones in puberty causes oil production to soar. Bacteria multiply nonstop when they can feed on oil. The thick oil and the bacterial population clog pores, the exit passage for oil. Inflammation occurs, and a pimple is born.

Treatment, therefore, consists of unclogging pores, reducing oil production and eliminating bacteria.

He should start with an over-the-counter acne medicine, one that contains benzoyl peroxide. He’ll have no trouble finding such a product. Benzoyl peroxide kills bacteria, dries the skin and unclogs clogged pores. He need not scrub his face raw with harsh soaps. He should wash it twice daily with a gentle soap like Dove. There is no special acne diet. Chocolate and greasy foods do not cause pimples.

If this regimen doesn’t work, he’ll have to see the doctor for prescription acne medicines.

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