Shocker: Wrist-Worn Fitness Trackers Not Particularly Accurate

It seems like every other person you see these days is sporting a fitness tracker/health monitor of some sort on their wrists. Heck, I’m wearing one right now. If you’re among the betrackered masses, I’ve got some bad news for you. You may want to be sitting down for this; maybe take a few deep breaths to prepare for the blow… When it comes to monitoring heart rate, these gizmos are not especially accurate. Shocking, I know!

I'm just going to assume that those droplets of liquid are blood.

I’m just going to assume that those droplets of liquid are blood.

Honestly, What Would A Cardiologist Know?!

This news comes on the heels of a new, as yet unpublished study by Cleveland Clinic heart specialist Dr. Marc Gillinov. Gillinov decided to study the fitness trackers’ accuracy after his teenaged daughters asked for devices of their own. After suggesting that the young ladies do some online research to find out which wrist-worn gizmo—Fitbit Charge, Apple Watch, Mio Fuse, Basis Peak—is the most accurate for heartrate monitoring, and discovering that there’s not really a heck of a lot of information out there, Gillinov was determined to find out for himself.

With the help of a group of volunteers—mostly young-ish, mostly relatively fit—Gillinov tested the four above-mentioned fitness monitors against each other. Volunteers first stood around doing nothing, then walked upon a treadmill, followed by running on it, with the health trackers taking readings. Volunteers also sported a chest-strap heart rate monitor and, as a control, a hospital-quality EKG reader.

Unsurprisingly, the chest-worn monitor—typically used by elite athletes for training purposes—was the most accurate, matching the EKG readers, um, readings 99% of the time. Second in accuracy were the Apple Watch and the Mio Fuse, with 91%. Fitbit was fourth at 84%, with the Basis Peak bringing up the rear with 83% accuracy. Heart-rate readings from all wrist-trackers were found to be both above and below the actual readings, at different times.

Gillinov noted that those readings would, unfortunately, be even less accurate for the peeps who really need these fitness trackers: fatties the obese. The wrist-worn devices measure the wearer’s heartrate by shining a light onto the skin and tracking changes in blood volume from heartbeat to heartbeat. How the heck that would work for even the fittest of folk is beyond me. Sounds like some kinda space sorcery. Anyway, according to Gillinov’s study, obesity, poor circulation, and high blood pressure could all cause these results to be inaccurate.

Technology ain’t all it’s cracked up to be sometimes.

Photo credit: vernieman via Foter.com / CC BY

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