Walking/ Running with fitbit in hand still showing updated heartrates as if being worn

[wpathuis]

Dear Fitbit,

I was holding the fitbit in my hand without the heart beat sensor making contact with my skin. I still get updates on my heartbeat as if I was wearing it correctly on my wrist. When I alter my speed the BPM responds as if I would have increased my intensity of activity instead of responding 'no measurement possible'. To me this suggest the current displayed BPM is estimated by an algorithm instead of by actual measurement. If the latter is true how accurate and relevant is this to my health insights?

Please could you describe the method of measuring and the accuracy of the Heart beat measuring? 

Thanks in advance, best,

Wiltfried

[JohnnyRow]

I expect in your case, the sensor lights were still reaching your skin to make measurements, though not as accurately.  If you were to try the same experiment with the sensors turned away from your hand toward open air, I expect you would get different results.

Optical heart rate sensors detect changes in blood flow corresponding to heart beats.  Presumably this could on any exposed skin, but Fitbits are designed for wear on the wrist.  This does not mean they won't work other places but do so at your own accuracy risk.

If you really want to know more on how these work, here is a good in-depth article on the technology in general, not specific to Fitbit:

Optical Heart Rate Monitoring: What You Need to Know

[wpathuis]

Thank you John for your reply and explanation!

In this case I am talking about the sensors pointing away from my skin. I repeated this with two other people owning a Fitbit. I like you to ask to do this as well:

- just walk wearing your fitbit

- take it off while walking and have a look at the fitbit bpm

- point it away from your skin and see what happens when you walk to run and go back to walking again

In this particular case I would expect just two dashes for not being able to measure but it is showing just as if you are wearing the fitbit on your wrist. Maybe you can give it a try as well and report back.

Thank you again for the reply.