Fitbit under- and overestimating HR
oat_bran
Posts: 370 Member
I've head my Fitbit Charge 2 for a little over a year. I remember that in the beginning it would often suddenly overestimate my HR at random moments during a workout. I know it says so in the manual that you need to move it higher up on the wrist during workouts for better accuracy but it would constantly slip down when I did it so I stopped bothering. It was just too inconvenient. Not to mention doing so didn't always fix the HR reading.
But later at some point I noticed that it stopped overestimating and started to always show accurate measurements. I know they were very accurate because I did an experiment where I tracked my intake, my fitbit's TDEE estimates and my weight on two separate spreadsheets for 5 months and the results very spot-on! I lost (or gained) exactly what I should have lost or gained according to my fitbit. These measurements were always consistant, i.e. similar level of activity always showed similar HR. Over this time I learned what my heart rate usually is at rest and during different activities and also how I feel at different heart rates.
Then about a month or so ago, to my frustration, all of a sudden it started overestimating heart rate again. For example, I would walk at a moderate pace, which means my HR should 80-110bpm but my fitbit would say 170. Then at other times, I noticed it underestimated the HR, like for example, during a bike ride uphill where my HR should be around 100-120bpm and it would say 50-60bpm, which is obviously *kitten*.
I wouldn't worry about its HR reading so much, but it greatly affects its TDEE estimates. It can create a 100-200 calorie different for one short workout and exercise practically everyday and more importantly base my intake on my fitbit's readings.
Has anyone had a similar experience with their fitbit ? Maybe it was something I did that made it start overestimate HR again?
Do the new generation of fitbits have the same problem? I was thinking of getting myself a Charge 3, but if it has the same HR I don't know if it's worth it...
But later at some point I noticed that it stopped overestimating and started to always show accurate measurements. I know they were very accurate because I did an experiment where I tracked my intake, my fitbit's TDEE estimates and my weight on two separate spreadsheets for 5 months and the results very spot-on! I lost (or gained) exactly what I should have lost or gained according to my fitbit. These measurements were always consistant, i.e. similar level of activity always showed similar HR. Over this time I learned what my heart rate usually is at rest and during different activities and also how I feel at different heart rates.
Then about a month or so ago, to my frustration, all of a sudden it started overestimating heart rate again. For example, I would walk at a moderate pace, which means my HR should 80-110bpm but my fitbit would say 170. Then at other times, I noticed it underestimated the HR, like for example, during a bike ride uphill where my HR should be around 100-120bpm and it would say 50-60bpm, which is obviously *kitten*.
I wouldn't worry about its HR reading so much, but it greatly affects its TDEE estimates. It can create a 100-200 calorie different for one short workout and exercise practically everyday and more importantly base my intake on my fitbit's readings.
Has anyone had a similar experience with their fitbit ? Maybe it was something I did that made it start overestimate HR again?
Do the new generation of fitbits have the same problem? I was thinking of getting myself a Charge 3, but if it has the same HR I don't know if it's worth it...
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Replies
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HR is merely a stat for viewing or tracking unless the Fitbit thinks you are working out - then you received HR-based calorie burn (except newer ones when you select Weights).
But steps and increased HR is needed for a block of time before it backtracks and starts calling the time a workout.
HR-based calorie burn is invalid use of formula for the estimate and they know it.
So daily life is step-based calorie burn which is better estimate.
It could be the sensor is really going bad for reading HR.
Usually the issue of it being high but reading low, or not reading at all - is common for some, but in this case, could be related.
Find the similar example workouts in date and time prior to and with issue, when you did the reset already, and you'll need to call support.
Yes they all use the same HR reading method, but that's not likely the issue since you saw a change.0 -
Could it be related to the time of year? It's getting colder where I am right now which means more vasoconstriction, less blood flow at the surface of the skin and therefore a harder time to measure HR optically1
