Pulse readings with Fitbit Sense

[london2000]

Hello, I know that activity monitors, including Fitbits, aren't very good at recording pulse rates but I would have thought that the trends would be in the right direction. However, the images below suggest not!

These images were recorded together in the same exercise session - one image shows the recording from a Polar chest strap (which measures electrical signals from the heart and is generally regarded as an accurate measure) and the other shows the output from my Fitbit Sense, worn on my wrist and which is using light to measure pulse via blood flow.

The exercise session consisted of 15 minutes on a crosstrainer (ie, elliptical machine), which was strenuous, followed by 20 minutes on an airglider, which was much easier to do.  Both machines use a similar action of arms and legs.

The Polar results show my heart rate dropping when I come off the crosstrainer, which is what I would expect. The results from the Fitbit show the opposite, bizarrely showing my pulse rate increasing as I move to the easier machine. I've repeated this experiment a number of times with the same results. Has any one else experienced anything similar?

Thanks, Roger 

[Rufous44]

Hello @london2000 ,

several users in the past posted comparisons between Fitbit Sense recording and other devices (including the excellent H10).

The response by Fitbit have been swinging between "Adjust your Sense at your wrist better" to "it's not a valid test to compate the two as the technlogies are different" and finally also deleting such posts and ban few users.

[london2000]

Thanks Rufous44,

Fitbit's attitude isn't very helpful! I've looked into this in the past, and made various adjustments to position and tightness, all to no avail.

I've also seen posts suggesting that sweat can cause incorrect recording of pulse rate by Fitbits, but I don't think that can be the explanation for my observations because my pulse rate apparently shot up rapidly once I swapped machines - too fast for the sweat to have evaporated from beneath the Fitbit.

A crosstrainer and an airglider have very similar arm actions, but the crosstrainer needs a lot more effort. The pulse rate recorded with the airglider is unrealistically high and I'm wondering if the reading you get is related to how much the arm muscles contract with the effort of pushing. (Conceivably, this could affect the penetration and reflection of the light beam used to detect flow of blood.) Perhaps pulse rate is overestimated when the muscles don't need to contract so much?

[IgorR11]

This is one of the most debated issues here on this forum, and there is no solution at all. Fitbit's support response says "we are aware of this and working towards a solution"; But the problem is that it's been years and this error is not corrected, the problem is not to be monitored on your wrist, only the fitbit sense readings are a joke compared to other competitors.