Not all wearables will monitor your heart rate accurately. But out of the many devices out there, the Apple Watch (the 2015 version, at least) is one of the better ones, according to a study featured in the peer-reviewed medical journal, JAMA Cardiology.
The research was conducted by Cleveland Clinic and compared four popular wearables on the market, the Apple Watch (2015), the Fitbit Charge HR, the Mio Alpha and the Basis Peak. Researchers took a sample size of 50 healthy participants and then measured their heart rate while walking, jogging and at rest. The heart rate readings of the four wearables were compared to the readings of a chest strap, and an electrocardiogram (EKG), which is considered the most accurate heart rate monitor. Compared to the EKG, the chest strap matched up 99 percent of the time, putting it ahead of wrist-worn wearables. The Apple Watch and Mio Alpha showed 91 percent accuracy on average, the Fitbit showed 84 percent and Basis Peak was about 83 percent accurate. This means that even the best wearables tested were wrong about 10 percent of the time, while others were off by about 20 percent.
"If you get a bizarre or almost unbelievable reading, don't worry about it," Marc Gillinov, one of the authors of the paper, told USA Today. "Check it once or twice more."
Some of the lack of accuracy can be attributed to the nature of wrist-worn sensors. A heart rate sensor needs to make contact with the skin, so if it's too loose, it can move around and return an inaccurate reading. Conversely, wearables use blood flow for measurements and having the device strapped on too tight will constrict the user's veins also resulting in inaccuracy.
But despite the solid findings, the study could be expanded in a few ways. There are a lot more than four wearables on the market, and perhaps companies' watches that didn't make the list give more accurate readings. Additionally, the wearables tested were all purchased in 2015 and since then many new wearables come out. Maybe the heart-sensor technology in newer devices has improved.
If you own one of these wearables, keep in mind that the heart rate data you see is "mostly" accurate. If you're looking to get your monitoring on, check out CNET's reccomendations for the best wearables of 2016.