DEAR DR. DONOHUE: I am writing to find out if I am the only person in the world who gets heartburn from running. This has sprung up only in the past year. When I tell others, my wife included, they give me a stunned look that is a strong statement of disbelief. Is exercise a cause of heartburn? What do I do for it? – N.N.

ANSWER: The official name for heartburn is GERD – gastroesophageal reflux disease. It’s an eruption of stomach acid and digestive juices into the esophagus, a structure not equipped to cope with those substances. The reason why it happens lies in a band of muscle – the esophageal sphincter.

Unless food is passing from the esophagus into the stomach, the sphincter muscle stays closed. In GERD, it remains open almost all the time. That permits stomach juices to ooze upward into the esophagus.

You are not the only person in the world who gets GERD from exercising. Weightlifters are quite likely to suffer from it. When heavy weights are lifted, pressure within the abdomen rise to great heights. That pressure causes stomach juices to shoot into the esophagus.

Weightlifters are not the only athletes who have the problem. It can also affect runners and bicyclists. Why it happens must be related to relaxation of the sphincter muscle, but the mechanism that causes such relaxation is not known. It just happens to some people.

You can deal with GERD just as those do who have it irrespective of exercise. Start by taking an antacid before you run, or carry an antacid with you while you run. If antacids offer no relief, then step up to medicines that suppress stomach acid production. Drugstore shelves are stacked with such drugs, and your pharmacist can help you make a choice.

DEAR DR. DONOHUE: Somewhere I read that your pulse after exercise is a good indication of heart health. If I remember correctly, the pulse should return to its normal rate after two minutes of rest. Is this the case? – P.N.

ANSWER: I have never heard the two-minute rule, but I do know another rule that connects heart health to the amount of time it takes a heart to return to its resting rate after exercise.

That rule says the heart rate should slow by 12 beats a minute after stopping exercise. That is supposed to be a valid indication of heart health.

If your resting pulse is 70 and your exercising pulse reaches 150, then a healthy person should take six to seven minutes to regain the resting pulse rate after exercising.

DEAR DR. DONOHUE: When I read articles on walking, words like “brisk” or “fast” always are used. What exactly is meant by “brisk walking” and “fast walking”? I have my own ideas but wonder if they are correct. – T.R.

ANSWER: I am not certain if exercise experts unanimously agree on what pace defines brisk and fast walking. Some say a brisk walk is a walk where a person takes 100 steps a minute, and a fast walk is one where a person takes 120 steps a minute.

How useful this information is can be a debatable issue. The length of a person’s stride is another gauge of walking intensity. So is the terrain on which a person walks. Uphill walking burns more calories than does walking on a level surface. Many factors, therefore, determine how best to walk for heart health.

DEAR DR. DONOHUE: I have been a faithful runner for many years. I am 42 now.

It was drummed into me that I should carry water with me and drink every 15 minutes to prevent dehydration. Thirst supposedly is not an early indication of water need. Now I am hearing just the opposite: Drink only when thirsty. Who’s right?

ANSWER: I am one of those who drummed the message of constant water drinking during long runs, and I also championed the idea that thirst was not an indication of water needs. The latest information says not to drink water compulsively during a run. It can cause a drop in body sodium, something that can cause big trouble. Now the word is to drink when thirsty.

DEAR DR. DONOHUE: I come from a large family — six boys and six girls. I am one of the girls. In March our father died from a bleeding stomach aneurysm. My older sister contacted all of us to say we should be checked for an aneurysm. She says they are hereditary. What are your recommendations? – H.H.

ANSWER: An aneurysm (ANN-your-izm) is a bulge that pops up on an artery. Frequently, that artery is the aorta, the body’s largest artery. And frequently, the bulge develops on that part of the aorta that passes through the abdomen. That makes it an abdominal aortic aneurysm.

The danger of an aneurysm lies in its potential to burst like an overinflated balloon. Aneurysm size indicates how close to bursting an aneurysm is. Ultrasound pictures of the aorta permit doctors to measure its size.

Your father’s story is an all-too-familiar one. His aneurysm produced no symptoms, so he was unaware that he faced a catastrophe. When an abdominal aneurysm breaks, a massive amount of blood gushes from it. In more than half of such cases, patients die even though they make it to the operating room for emergency surgery. The goal of treatment is early detection and surgery when the size of the bulge puts it in a danger zone.

Inherited? There is a slight genetic influence at work. About 15 percent of aneurysm patients have a close relative who is incubating one.

You and all your brothers and sisters ought to tell your family doctors about your father’s aneurysm. The doctor will take pains to look carefully for aneurysm signs. Sometimes doctors can feel the pulsation of an aneurysm during a physical examination. The doctor, with a stethoscope, might also hear a bruit (brew-EE), a sound blood makes as it passes through an aorta that has an aneurysm.

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.