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The heart of the matter: What your pulse says about your health

POSTED: February 9, 2016 2:51 p.m.
Jennifer Graham/

If you have an abnormally low heart rate, you could need a pacemaker. Or, you could be a world-class athlete in phenomenal shape. What's normal, what's not, and should you be monitoring yours?

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If you have an abnormally low heart rate, you could a serious heart condition and need a pacemaker. Or you could be a world-class athlete in phenomenal shape.

The speed at which a heart pumps blood throughout the body varies widely, and this can be confusing to anyone tracking their heart rate through high-tech fitness gadgets, or the low-tech, but still accurate, method: holding two fingers to your neck or wrist and counting the beats.

A slow heart rate can be a sign of phenomenal fitness; former President George W. Bush used to tout his resting pulse — 43 when he was in office — as a sign of his good health. But a heart rate below 60 beats per minute, according to the American Heart Association, indicates bradycardia, a potentially life-threatening condition indicative of a malfunction of the heart's electrical system.

Further adding to the confusion are recent charges that Fitbit, a popular personal health monitor, gives dangerously inaccurate heart-rate readings. So what’s a normal heart rate anyway, and is it something people even need to know?

“Normal can be anywhere between 50 and 100 beats per minute,” said Dr. Roderick Tung, a cardiologist and professor of medicine at the University of Chicago. “It’s a huge range, and you can’t really say what the ideal heart rate is.”

But that doesn't mean we're not trying. One in 10 Americans use a "wearable," the industry term for a personal health monitoring device. The heart rate it displays is a number influenced both by genetics and how much a person exercises.

“Your cardiac input is determined by two things: how many liters per minute the heart is available to pump, and also its stroke volume, how much blood is ejected per squeeze,” Tung said, using athlete Lance Armstrong as an example.

“He’s so well conditioned that when his heart squeezes, it probably ejects twice as much blood as you and I, and it can go at half the rate of most people because it’s so powerful.

“A slow-heart rate can be a great thing in a well-conditioned individual, but it’s a problem when it’s not a well-conditioned person. We also know that aging also makes a difference. Heart rates start slowing down when people age," Tung said.

When Denver running coach Mary-Katherine Fleming was a girl growing up in rural Tennessee, a medical-grade heart-rate monitor was always in the house, because her father had serious cardiac issues that led to six heart attacks and a transplant. Back then, Fleming said, the device was “huge and expensive; it cost an insane amount of money.”

When Fleming took up running and looked at fitness monitors for herself in 1994, a heart-rate monitor was still out of her price range. Now, however, they can be had for $30. Apple watches take heart readings every 10 minutes. And parents can even buy tiny "smart" socks that monitor a baby’s heart rate and breathing.

“We’re living in an era in which everyone is checking their vitals,” Tung said, adding that this is a double-edged sword.

“A certain amount of self-awareness can be helpful when used appropriately, but it often becomes an obsession that can be unhealthy.” Moreover, he said, simply the act of checking your heart rate, if you’re concerned about it, can affect it because anxiety increases your heart rate and blood pressure.

Then there’s the matter of accuracy.

In a lawsuit filed earlier this year, some users of Fitbit charged that the popular device gave heart-rate readings so wrong that they could be dangerous to people using one to determine how hard they should exercise. The accuracy of Apple watches has been challenged, as well.

Many runners, cyclists and other athletes use the devices for training, monitoring the number constantly and maintaining a level of exertion that is a percentage of their maximum heart rate, the limit of how hard and fast their hearts can beat. (It's the opposite of the resting pulse, the number of times the heart beats in a minute when a person is completely still. That's best to measure when you first wake up in the morning, before you get out of bed.)

Fitbit stands by its accuracy, as does Consumer Reports magazine, which tested the devices and found them satisfactory.

Fleming, the running coach, uses a Polar heart-rate monitor and recommends them to her clients who are trying to improve both their running pace and levels of fitness. Ironically, they are often used not to spur runners to go faster, but to slow down.

Dimity McDowell, one of Fleming's clients, is training for the Superior 50K race in Minnesota by using a heart-rate monitor to slow herself down, running at a pace that keeps her heart rate under 140. The heart-rate monitor has been essential for that, she said.

“I knew it was going to be slow, but I didn’t know how slow, or what that would feel like,” McDowell said. “I feel like I’m warming up for the run, not doing the real run. But I love finishing a run and not feeling like I completely wasted myself for the day,” she said.

A 43-year-old author and co-founder of an online community for moms who are runners, McDowell said she's not normally a number cruncher — “I’m hard-pressed to know my PRs; I don’t run for the clock or for data” — but she believes that monitoring her heart rate is helping her with her goal to train for a grueling event without being injured like she has in the past.

“Running is something it’s easy to get carried away with,” she said. “So many people would benefit from this.”

For some people, however, heart-rate monitoring is a temporary way for their doctor to determine if a problem warrants a pacemaker or heart surgery; coronary patients often wear devices for a short time that provides data for a diagnosis. Even for athletes, they can amount to little more than a fad, according to Matt Fitzgerald, an endurance athlete and author.

“There’s a gee-whiz factor for the first week. But a lot of heart-rate monitors end up in a drawer collecting dust,” Fitzgerald said. “When you’re in the process of getting in shape, it can be fun to track your heart rate. (A dropping resting pulse) is a sign that your heart is becoming more powerful and it’s adapting. But once you’re in really good shape, your morning pulse won’t change that much, although it may change a little bit day to day based on how fatigued you are,” he said.

Fitzgerald, who is currently training for a 50-mile ultramarathon in April, said he no longer uses a heart-rate monitor because, as a lifelong athlete, he has become adept at judging the intensity of his effort and how he needs to perform to achieve his health and fitness goals.

“Research says there’s no better way to assess your fatigue level than to ask yourself how you feel. Your body itself is a pretty amazing piece of technology,” he said.

For his part, Tung, the Chicago cardiologist, said most people don't even need to worry about their pulse, unless their doctors insist. A well-functioning heart, he said, should be like well-functioning lungs: something you don't even notice.

Ideally, “Nobody should think about breathing, and nobody should think about their heart rate,” Tung said. “Often we have to tell people, ‘You’re fine, stop monitoring yourself.’ Rare is the patient that needs to monitor himself more.”
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