[collias]

Do you do any accounting or normalizing for clearly erroneous heart rate readings from the watch?

Just anecdotally, the heart rate monitor seems to be wildly inaccurate at times. Over the course of a workout at the gym, my heart rate jumped to 170bpm while benching (probably close to correct), and dropped to 45bpm while deadlifting (definitely incorrect). My resting heart rate is ~55bpm.

After a few days of seeing my heart rate have a delta of ~100bpm in the matter of seconds, I've given up on the heart rate monitor being good for much.

Maybe I'm an outlier and it's accurate for other people, but for me, it was very disappointing.

[brandonb]

We'd love to do a validation study to get a definitive answer to this question.

Anecdotally, the Apple Watch is within about 5bpm of my AliveCor (an FDA-approved medical device), even while running. And it's been similarly accurate on most (but not all) patients in arrhythmias.

That said, we know accuracy will vary across skin tone, body mass index, pulse pressure, sweat, and we need to understand that more precisely before the AW can start to have real medical applications.

[rrss1122]

You can try getting a tighter fit and see if that helps.

I've noticed with any consumer heart rate monitor, if the fit is not tight and the monitor moves even a little bit, the heart rate the monitor reports will be off. I'm assuming the same will apply to the Apple watch.

[brandonb]

That's good advice. When I had a Moto 360, I also sometimes did the opposite: loosen the strap one notch, and slide it up my arm slightly till it was taught again. Your forearm is a slightly easier place to measure pulse than on a bony wrist.

[collias]

Interesting thought. I'm going to try to place it further up my arm and see if it helps.

Thanks!

[kevhsu]

I haven't worked with the Apple Watch, but for the Microsoft Band, the SDK will return a confidence level for the heart rate. I think both devices usually display the number regardless of confidence level to the user, sometimes with a signification that it is still acquiring your heart rate.