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Should you be concerned about a low resting heart rate?

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February 6, 2022 at 9:00 a.m. EST
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Sure, your heart speeds up when you watch an action movie or watch your child do a dangerous move in gymnastics.

But if your heart is a slowpoke the rest of the time, your health could be at risk.

Cardiologists consider a pulse rate of between 60 and 100 beats per minute to be normal, and over the course of adulthood, our resting heart rate (RHR) usually manage to be pretty consistent.

The vast majority of U.S. adults fall into the normal range. In a 2011 study of a decade’s worth of heart-rate data from 49,000 American adults, the average RHR was 72 beats per minute.

But some of the RHRs studied were, well, slow. About 15 percent of the men and 6.9 percent of the women had an abnormally low RHR of fewer than 60 beats per minute — a phenomenon known as bradycardia.

What your heart rate can — and can’t — tell you about your health

Researchers are still trying to disentangle the many factors that may cause the condition. One that’s key is the autonomic nervous system, the control center that keeps our internal organs humming so we don’t have to initiate every breath or beat. (It also controls digestion and even sexual arousal.)

That system has two parts: the sympathetic nervous system, which responds to perceived threats and speeds things up internally, and the parasympathetic nervous system, which calms our processes down.

If you’re in a situation your body interprets as dangerous or stressful, your heartbeat will race thanks to your sympathetic nerves. Once the stressor goes away, your parasympathetic nervous system helps slow it back down.

Another term for the job the parasympathetic nervous system does to help our organs chill is vagal tone, named after the nerve that dominates that process. People with higher measures of vagal tone often have something in common — high levels of physical fitness and very low heart rates.

A large percentage of endurance athletes have RHRs as low as 40 beats per minute, and even lower when they sleep.

Though their vagal tone could be the reason, researchers are still figuring out why marathon runners, elite cyclists and triathletes tend to have such low heart rates. The reasons may still be tangled, but there’s an emerging consensus that endurance athletes with bradycardia shouldn’t worry about their low heart rate unless they have symptoms such as chest pain, confusion or dizziness.

That doesn’t let the rest of us off the hook, however.

Elevated heart rate may increase risk for dementia

“If your resting heart rate is below 60 and you’re not a really good athlete, or above 100, you should at least mention it to your family practice or internal medicine doctor,” says Kenneth Ellenbogen, a cardiologist who specializes in treating patients with abnormal heart rhythms at Virginia Commonwealth University.

Since it interrupts the flow of oxygen-rich blood to our brain and organs, a low heart rate can be accompanied by things such as dizziness or fainting. And it can point to an underlying heart disease or an electrical issue within the heart itself.

“The most common thing that causes a slow heart rate is some abnormality in the conduction system,” says Ellenbogen, referring to the electrical impulses your heart sends and receives from specialized muscle cells within the heart’s walls. The efficiency of that system can be reduced by factors such as age, and could be caused by high blood pressure, congestive heart failure and other heart diseases.

Hypothyroidism can be to blame, or a variety of medications, including cardiovascular drugs such as beta-blockers, chemotherapy treatments and mood stabilizers.

How heart-rate training can help you target your exercise and improve your fitness

If you do have an abnormally slow heart rate, expect tests such as an EKG or ongoing heart monitoring. Often, a change in medication can solve the problem. But in some cases, a slow heart rate may pose a risk to a person’s organs. In those cases, implantable pacemakers can restore the heart to a speedier rhythm.

If your heart does beat sluggishly (or you’re worried it does), help could be as close as your wrist. Ellenbogen recommends that all of his patients with electrical heart disease wear a watch to help monitor their heart rate.

“Soon we’ll have clothing that does this,” he says. Knowing more about your average resting heart rate — and seeking help when it looks wonky — is half the battle.

“Sixty to 100 beats per minute,” Ellenbogen says. “That gives you a ballpark to work in.”