DEAR DR. DONOHUE: I am 59 and have had a jogging program for quite some time. I don’t think it’s doing me much good. Perhaps I don’t jog fast enough, but I can’t go much faster than I am currently doing or I become completely out of breath and have to stop. What can I do to make my exercise more beneficial? – P.P.

ANSWER: Try interval exercise. It’s a combination of intense and less-intense exercise.

If a person is fit and able, strenuous exercise is better than moderate exercise. For the rest of us, moderate exercise is better than light exercise, and light exercise is better than no exercise. A tenet of exercise teaching has been that heart exercise has to be continuous exercise for a given period of time. That’s not exactly the case. Interval exercise benefits the heart and cardiovascular system as well as, if not better than, nonstop exercise.

Interval exercise consists of intense exercise for a short time followed by exercise at a greatly reduced level. For example, you run hard for one minute and then walk for three minutes. You continue this cycle of running and walking for as long as you can, ideally for 30 to 60 minutes. You won’t be able to do that length of time when you start, but that’s the eventual goal. When you are accustomed to this cycle, you extend the time spent running and reduce the time spent walking, but you don’t ever eliminate the less-intense periods.

This kind of exercise is often used by elite runners and swimmers. It’s not new. It was developed in the 1940s and has served as the training method of many Olympic teams that have won gold medals. These athletes train at a very strenuous rates, ones not suggested for the average person.

The interval training plan comes with the familiar warning for all exercise: It should be undertaken at older ages only with a doctor’s approval. Exercise can be deadly if it’s done by people with unrecognized health and heart problems.

DEAR DR. DONOHUE: I am a 52-year-old runner who returned to competitive running six years ago in the 1 mile and 1,500 meter category. This year I really hit it hard and qualified for the National Senior Olympics in Louisville, Ky. I started a training regimen in March. Although the Senior Olympics is over, I still participate in local races. My problem is not one of muscle pulls or sprain, but one of lung capacity. I still don’t have the stamina I need to run a really good race. Is there something I can do so that I am not sucking air three-fourths of the way through the race? The winner in the Senior Olympics ran the 1,500 meter race in 4:36. I ran it in 6:19. You can see I need help. – G.N.

ANSWER: I beg your pardon. I’m in awe of your time.

Have you ever had pulmonary function tests? They give you an accurate assessment of your lung capacity and show where you are in relation to others of your age. I don’t know of any way to improve lung capacity other than the kind of training you already subject yourself to. I suppose you could go at it even harder, but I would get the lung tests before pushing yourself any more than you already do.

The only other thought I have is one on nutrition. Perhaps what you call running out of stamina is not related to your lungs but to the amount of glycogen stored in your muscles. Glycogen is muscle sugar and is the fuel needed to power you through a run. You can increase the amount of muscle glycogen by increasing the amount of carbohydrates in your diet.

DEAR DR. DONOHUE: I think I saw where you once wrote that sit-ups and leg raises will never take weight off the tummy. What will do it? – D.L.

ANSWER: I have said that abdominal exercises don’t selectively remove fat from the stomach. Fat goes from all fat storage depots, one of which happens to be the abdominal fat depot, but abdominal exercises don’t remove fat exclusively from that site.

Abdominal exercises do strengthen abdominal muscles. That keeps abdominal organs in place. Strong abdominal muscles act like a girdle and prevent stomach bulging.

DEAR DR. DONOHUE: I have systemic lupus erythematosus. My doctor says it has damaged my kidneys, and he calls it class III. Can you help me understand this? I am on CellCept. – R.S.

ANSWER: When “systemic” is attached to a disease, it indicates the involvement of many organs and tissues, with the emergence of many signs and symptoms.

With systemic lupus, skin, joints, the nervous system, the heart and the kidneys can be affected. Lupus is an autoimmune disease. That means the immune system has attacked its own body and organs.

A large percentage of lupus patients suffer from lupus kidney damage. Class III signifies that the kidney involvement is localized to a few kidney areas and affects less than 50 percent of the kidney’s filtering stations.

Your medicine, CellCept, reins in an immune system gone wild. It should help the kidney problem too.

If things do not straighten up, people with lupus nephritis – as the kidney involvement is called – have the option of dialysis or kidney transplant. But don’t take that to mean that either is your destiny.

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