DEAR DR. DONOHUE: I am a 68-year-old man, 5 feet 8 inches tall and 135 pounds. I have been a runner for 36 years and have completed four marathons. I currently run about 25 miles per week. My resting pulse rate was 56 until four years ago. It suddenly increased to 70 and has remained there since. The increase in my resting pulse rate concerns me but not my doctor. Why do you think this has happened? – L.N.

ANSWER: So we are all on the same page in the same book, we need a few basics. Pulse rate and heartbeat are the same thing. If your pulse rate is 80 a minute, then your heart beats 80 times a minute. The pulse is simply the wave of pressure imparted to the circulating blood from the heart’s having pumped blood into arteries.

Second, a heart in peak condition beats more slowly, so the pulse rate is slower. The heart of a well-conditioned runner, such as you, pumps more blood with each beat. Such a heart, therefore, can beat more slowly and still circulate an abundant supply of blood with fewer beats.

A fast resting pulse rate – the pulse rate when a person sits quietly – can indicate heart problems. A slowly beating resting heart can be normal, abnormal or a sign of superior health. Not as much information comes from a slowly beating heart as comes from a rapidly beating one.

A normal resting pulse rate can range from 50 to 100. Some say that a resting pulse rate should not be more than 20 beats faster than the “average” resting pulse rate. That average number is 70 for a man and 73 for a woman. According to those who preach these numbers, a man’s resting pulse rate should not exceed 90, nor should a woman’s exceed 93. The experts are at odds with themselves on this matter.

Your resting pulse is normal. Why it sped up four years ago is a hard question to answer. Perhaps you are not giving yourself enough rest. An overtaxed heart beats faster. Take a break and see what happens. Or, age might be the explanation. The pulse rate increases with age. Or it could be that you are under great emotional stress. That causes an increased resting pulse rate.

Stop obsessing about this. You are going to make yourself ill from thinking too much of something that should not be given such great attention.

DEAR DR. DONOHUE: My wife calls me a couch potato because I spend so much time on the couch watching football games. I tell her the excitement gets my heart beating faster, so I am exercising. What do you say? – D.D.

ANSWER: I say “nice try.”

A fast-beating heart is not always due to exercise. Fright, public performance and smoking a cigarette are examples of conditions where the heart beats faster without any health benefit.

In these instances, the fast heartbeat comes from the outpouring of chemical messengers that prepare us to fight or retreat.

The speed with which the heart beats cannot be taken as the sole criterion for exercise benefit. The determinant of that depends on energy consumed. You are not consuming one iota of energy watching television.

DEAR DR. DONOHUE: I am a 52-year-old male who jogs regularly. I average about 1,400 miles a year. About 10 years ago, I noticed my left chest was slightly larger than my right. My doctor at the time said I could have a twisted heart or possibly have had small strokes. He ordered an immediate stress test, which was normal. I believe that running has enlarged my heart, and that has caused the left chest to be larger. Is that reasonable? – J.W.

ANSWER: The right side and left side of the body are never symmetrical. Measure the right and left sides of anyone, and you are going to find a difference. In arms and legs, the dominant extremity is always larger.

Nature gave you a slightly larger left chest than right chest. It has nothing to do with your heart being enlarged.

You do not have a twisted heart. You have not had small strokes.

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.