pulse too low for ECG

[dz1234]

I have been trying to use the ECG and every time I try it gives me an "inconclusive" reading, because my heart rate is below 50 (which is true). It is ridiculous that the device is unable to render a reading for someone with a low pulse. If the problem is that it can't average enough beats, then maybe give an option to record for a minute rather than 30 seconds. Ugh....

[LZeeW · Accepted solution]

@dz1234   Let me explain how this works.  The ECG is a medically regulated feature, meaning it needed FDA approval for release.  Fitbit ran a validation study that is described in the Fitbit ECG app Physician's Guide.  All studies have confidence intervals for sensitivity and specificity.  Based on the study results, Fitbit asked for approval for with a low heart rate of 50 and an high heart rate of 120.  In order to lower that low heart rate threshold, Fitbit would have to conduct another study and submit the new data for approval.

I can think of two reasons why the lower heart rate was set at 50.  Fitbit's algorithm couldn't meet the sensitivity and specificity parameters when the heart rate was below 50.  There weren't enough people in the study who had a heart rate less than 50.

You should also know that the Apple Watch and Samsung Galaxy also have 50 bpm as low heart rate limit.

[dz1234]

While I understand this now, it is something that would be nice to be aware of before purchasing. Nowhere in their advertisement for the device do they mention that ECG is only available for resting heart rates between 50 and 120.