Accuracy varies among wrist-worn heart rate monitoring wearables

In a new study comparing the accuracy of four wristband heart rate monitoring wearable devices, the Apple Watch proved more accurate than the Fitbit Charge HR, the Mio Alpha and the Basis Peak, Cleveland Clinic researchers said. 

For the study, published in JAMA Cardiology, the researchers also compared the devices to two traditional chest-band electrode systems. Fifty healthy adults underwent various physical activities while wearing the devices

The wearables all revealed variable accuracy, the authors said, who noted that further research on different types of exercise and other devices is necessary. The Watch hit about 90 percent accuracy while the other wearables were in the low 80s, study author Gorgon Blackburn told Time.

“What we really noticed was all of the devices did not [do] a bad job at rest for being accurate for their heart rate, but as the activity intensity went up, we saw more and more variability,” said Blackburn, the director of cardiac rehabilitation at Cleveland Clinic. “At the higher levels of activity, some of the wrist technology was not accurate at all.”

Meanwhile, the traditional chest strap tool hit 99 percent accuracy.

Apple is continuing its push into the healthcare realm, recently buying digital heath records maker Gliimpse while also working the development of new Watch apps, one targeting heart rate recovery measurement. This past March Apple debuted a framework to help hospitals and developers build apps for health management. In August, it was reported that the company filed an application for a wearable that would record electrocardiographic signals and may be developing a wearable boasting 3-D touch technology daily health data collection.

The study’s results drew comment from Fitbit, which told Time via a statement that its trackers are “not intended to be medical devices” and that internal testing showed an accuracy rate of 94 percent.

Bruce Schatz, a professor and head of the department of medical information science in the college of medicine at the University of Illinois at Urbana-Champaign, told FierceHealthIT earlier this year that devices like Fitbit and Jawbone lack the accuracy to be able to measure relevant medical information, calling the packaging limited.

“The battery is supposed to last for a month without recharging," Schatz said. "It’s something that you put on and leave on for a long period of time, and because of that, the battery has to be saved somehow.”

Schatz added that a typical Fitbit will measure motion once a second, while a typical medical device will sample 100 times per second. "In order to measure walking accurately, you need on the order of 20 samples per second," he said.