DEAR DR. DONOHUE: I am a 59-year-old woman and have decided to get into shape using Pilates exercises. I heard about them on the radio, and it piqued my interest. I am not too familiar with the method. Do you think they are worthwhile? – M.M.

ANSWER: Yes, they’re worthwhile. Joseph Pilates (pul-LAH-tease) devised these exercises in the early 20th century and kept on perfecting them for the next 50 years. I have seen pictures of him in his 60s, and he was in tiptop shape.

Some Pilates exercises are done with machines. Those exercises are for the more advanced. You’re speaking of exercises done on a mat, right? They are easy on joints, and they give the total body a workout.

Pilates instructors stress smooth, even motions done with precision and care. Proper breathing during the exercises is emphasized. People are told to inhale through the nose and exhale through the mouth. Inhaling is accomplished by lowering the diaphragm. You know you are using the diaphragm if the belly sticks out while you breathe in. In exhaling, people draw their navels toward their backs while keeping their mouths open.

Core-muscle exercises are stressed. The core muscles are the abdominal, the lower back, pelvic, buttock and thigh muscles. These muscles take part in all movements, and they are important for maintaining proper posture.

One typical exercise is done while lying with the back on a mat, the knees bent and the arms alongside the body. The exerciser curls the head and shoulder toward the knees and holds that position while moving the arms up and down five times. As the arms are moved upward, the exerciser breathes in; on the downward movement, breathes out.

You’ll get much out of supervised Pilates training.

DEAR DR. DONOHUE: You have recommended for weight training that people start out with eight reps and work up to 12 reps. When they can do 12, then they increase the weight and begin again with eight reps.

That’s sound advice for young guys and gals, but how about us old codgers? – C.M.

ANSWER: The same advice applies to everyone, old and young codgers. Older people should start out with very light weights – perhaps a pound, or any amount they can lift eight consecutive times. If eight lifts are too fatiguing, then lift as many times as you can before taking a break. Work toward the eight-lift goal, and then work toward the ultimate goal of 12 lifts before increasing the amount of weight lifted.

DEAR DR. DONOHUE: I bicycle at a speed of 13 mph on an old, one-speed, no-gear bike. My age is 77. How does this compare with jogging at a pace of 4.5 mph?

I find biking easier on my knees, and it seems to give my thighs a good workout. – J.W.

ANSWER: They compare favorably. Biking at 13 mph burns a little more than 10 calories a minute. Jogging at a pace of 4.5 mph burns just about the same number of calories.

How can jogging at a slower rate provide equivalent calorie burning? In jogging, the feet and legs support the entire body weight. In biking, much of the body weight is supported by the bike seat and the wheels.

If you like biking and if it saves your knees, stick with it.

DEAR DR. DONOHUE: All my life I have wondered how people arrive at their body frame. I hear so many give their weight and then say, “My body frame is large, so I can carry all that weight.” Will you tell me what they base their frame size on? – M.K.

ANSWER: I think many people determine their “frame” size by looking in the mirror and declaring they have a large frame.

A simple way of classifying yourself as having a large, medium or small frame is to wrap your thumb and middle finger of the opposite hand around the dominant wrist. (If right-handed, wrap the left hand fingers around the right wrist; just the opposite for a leftie.) If the fingertip of the middle finger and thumb tip touch, you have a medium frame. If there’s a space between them, you’ve a large frame. If they overlap, you’ve a small frame.

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.