Stationary bike about as good for you as cycling

Dear Dr. Donohue: I would appreciate your evaluation of exercising on a stationary, upright bike (in bad weather) as compared with a street bicycle or just plain walking. I am an 86-year-old male. — F.F.

A: A stationary, upright bike provides excellent exercise for both the heart and the leg muscles. Outdoor biking, because of the wind, terrain variations and the fact that you’re propelling your body weight, is more taxing. If you can increase the amount of pressure needed to turn the stationary bike’s pedals, that would put both on an equal plane.

The same goes for walking. With each step, you’re supporting and transporting your body weight.

You’re not wasting your time on the stationary bike. It’s a great way to continue to exercise on days where the weather doesn’t permit outside exercise. And you’re getting approximately the same benefits.

Dear Dr. Donohue: At a recent cocktail party, a nurse admonished me for chewing ice. She said it indicates an iron deficiency. I get blood work done every six months. My doctor has never said anything about an iron deficiency or any other issue. I am 65 and in good health. — C.H.

A: The nurse was talking about pica. It’s a craving for materials not considered foods, like ice, clay, starch and dirt, to mention a few. Sometimes it is an indication of iron deficiency, but far from always. In someone like you, who has lab tests done twice a year, you’re not anemic and don’t have pica. You do, however, have a habit that will ruin your teeth if you don’t stop.

Dear Dr. Donohue: Do you rec- ommend physical therapy after knee surgery? If so, why? — T.C.

A: What kind of surgery? Replacement of the knee joint almost always requires post-op physical therapy.

The therapist teaches you exercises that restore the strength of leg muscles that have been spottily used because of knee pain. You’ll learn what’s safe for you to do and what’s not. Even if the surgery didn’t involve joint replacement, quite a few knee procedures are followed by physical therapy for the same reasons.

Dear Dr. Donohue: Fifteen minutes after taking a shower, I start itching, and the itch lasts about 20 minutes. What is this? — O.J.

A: I’m not sure. It might be aquagenic pruritus. “Pruritus” is the medical word for itchiness. Pretreatment with an antihistamine before showering can sometimes prevent the itching. Take it about an hour before you shower.

Tiny hives also break out on the skin. They may be so tiny you can’t see them, or they may be in places where you can’t see them. I don’t know if I’m correct. Aquagenic pruritus is so rare that I never expected to hear anyone complain of it. Get this confirmed by a dermatologist.

Write to Dr. Donohue, c/ o TSS, 1 Yonge St., Toronto, ON, M5E 1E6. The doctor is unable to answer individual letters.