Dear Doctor: Active senior endurance athlete worries his low heart rate may be dangerous

DEAR DR. ROACH: I am a 64-year-old male who is a lifelong endurance athlete. For the past 15 years, my primary activities are cycling and swimming. I work out around 10 hours a week now, so it’s nothing really excessive. But I always push myself to the edge of what’s a comfortable pace.

My lifelong cardio exercise enthusiasm has resulted in my pulse being low. My resting pulse is 47-48 bpm, and at times, it will go even lower. Normally this is a sign of good health, but now that I’m older, I wonder if this is too much of a good thing. My blood pressure is not especially low (136/76 mm Hg), and I am in otherwise very good health. Is a low pulse a concern now that I’m a senior citizen? — B.L.

ANSWER: You are exactly right that a slow heart rate in an athlete is normally the sign of a healthy heart. However, you are also right that too slow of a heart rate, especially in older people, can be a problem. The most critical issue is the presence of symptoms.

For many people, the symptoms can be subtle. They notice that they get tired a little more easily, which they will often believe is due to being older. (As a side note, is 64 really a senior citizen? Sixty-four seems younger the older I get.) Lightheadedness, feeling like you are going to faint, and actually fainting are more likely to bring a person to see their doctor to make the diagnosis. This will often bring about a recommendation to treat the slow heart rate.

For an athlete like you, another critical issue is your heart’s ability to exercise at a high level. You probably know what your times are for cycling and swimming, and if you find that you aren’t able to meet these times with the same effort, this could be a sign that your heart is affected.

When the pulse is very low, in the low 30s or slower, most experts will recommend treatment even if a person isn’t noticing symptoms. It’s likely they will feel better after treatment (which is almost always a permanent pacemaker) and only realize afterward how affected they really were.

So, if you aren’t having symptoms and are performing near your usual level, I wouldn’t worry too much, and I don’t recommend that you reduce your exercise. An electrocardiogram (EKG) to be sure that there is not something else going on (like heart block), as well as thyroid blood tests, would probably be prudent.