Several new fitness trackers, along with heart rate monitors, allow users to constantly measure their heart rate throughout the day. For the average person, this information may be interesting, but it remains to be seen whether it can help make you healthier, experts say.
Heart rate monitors geared toward athletes have been available for years, but recently, fitness trackers aimed at the general public have started to include heart rate as a measure to track along with steps taken, calories burned, distanced walked and sleep.
For example, the Withings Pulse includes a sensor that lets you check your heart rate using your finger, and the Basis B1 has heart rate monitor built into the wristband itself, allowing you to know your rate at any time. (The Basis also graphs this information, so users can see how their heart rate changed during the day or night.)
Knowing your heart rate can be useful when you exercise, because it will help you know whether your exercise is intense enough to provide health benefits, but not so intense that it could cause health problems, said Dr. James Borchers, a sports medicine physician at Ohio State University Wexner Medical Center. This sweet spot is known as the "target zone," which is about 60 to 80 percent of your maximum heart rate, according to the Cleveland Clinic. [The Best Heart Rate Monitor Watches for Exercise]
But there's little evidence that keeping track of your heart rate every minute, when you're not exercising, could provide health benefits for the average person, although it might satisfy curiosity.
"For a typical person, to monitor the heart rate throughout the day … there's no research saying how that can be useful yet," beyond just providing a number that some users might find interesting, said Clinton Brawner, a clinical exercise physiologist at Henry Ford Hospital in Detroit.
In fact, doctors don't recommended that healthy people monitor only their heart rate on a daily basis, said Dr. Ragavendra Baliga, associate director of Ohio State Medical Center's Division of Cardiovascular Medicine. That's because heart rate naturally fluctuates during the day, from about 60 to 100 beats per minute, depending on what you're doing, Baliga said.
Still, activity trackers with heart rate monitors may motivate people to be more active, and achieve their heart rate goals, Baliga said.
Brawner agreed. "If it engages you, and helps you be more physically active, then it’s the best tool in the world," he said.
And there are some situations where tracking your heart rate over time may be useful:
If you've started an exercise program, a decrease in your resting heart rate is one indication that your fitness is improving, Brawner said. It takes about four to six weeks of following an exercise program before people see measurable changes in their resting heart rate, Brawner said.
If you are learning to use stress management techniques, you might use a heart rate monitor to see whether your techniques (for example, practicing deep breathing) helped your heart rate go down, Brawner said.
Tracking heart rate along with activity may tell users which of their daily activities count as exercise, Borchers said.
People with heart problems can monitor their heart rate to know whether their heart rate is related to certain symptoms (such as lightheadedness), Brawner said.
There are some ways to estimate maximum heart rate (an often-used formula is to subtract your age from 220), but because heart rate is so individual, Brawner said these are crude estimates, and it is best to measure maximum heart rate in a lab.
Borchers recommended that people speak with their doctor about how to use their resting heart rate to calculate their target zone (which can be done by using a measure known as "heart rate reserve").
Some people may not need to measure their heart rate to know that they are exercising in their target zone: They can simply go by how they feel.
"If a person feels like they are exercising at moderate intensity, if you put a heart rate monitor on them, their heart is going to say they're exercising at moderate intensities," Brandon Alderman, a professor of exercise science at Rutgers University, told LiveScience in an interview earlier this month.
But for others, knowing their target heart rate "quantifies it a little bit more than 'how do I feel,'" Borchers said.
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