Target heart rate goals changing

[Nikiemac4]

I’ve noticed since the change of the activity zone minutes that the heart rate requirement keeps changing too. The last few weeks my lowest heart rate to hit fat burning zone was 112, but today suddenly it is 118? It’s not the first time it’s changed like that but I was finally able to get screen shots to show the change. It makes it really hard to keep getting zone minutes when it’s different requirements all the time. Why does it keep changing?

[LiliyaFitbit]

Welcome to the Fitbit Community, @Nikiemac4.

Thanks for the details shared in your post. I understand your concern and appreciate your efforts on getting screenshots. I was able to see that you have already contacted our Support team. If you still need help, please feel free to contact our team back as they have already all the details and special tools to continue assisting you. 

See you around.

[Nikiemac4]

I still need help! The chat was not helpful, can someone please email me?

Sent from my iPhone

[LiliyaFitbit]

Thank you for your reply, @Nikiemac4.

I am sorry to hear about your experience. Since our Support team have already all the details of your case, please get is touch with them again. They can follow up with you via email if you prefer. I appreciate your understanding and look forward to getting you back on track.

Meanwhile, I recommend trying to change your heart rate zones using the web dashboard: log in fitbit.com on a browser (not on Fitbit app), click the Gear icon at the right top corner and select Settings, click the Edit button next to the Heart rate zones, select Custom for both Heart rate zone and Max heart rate, and click Submit to save the settings.

Hope this helps!

[MrMarv]

@Nikiemac4 -

@LiliyaFitbit is missing the whole "Heart Rate Reserve" method that FitBit put into place last year. You do not mention which device you have, but I suspect it is a later version device (last three years).

If you do not have a Custom Max HR set then only two things can make your heart rate zone definitions change:

    Your age has changed

           and/or

   Your resting heart rate changes

A change in age will rarely drive a change in zones and definitely not to the degree you have stated.

But changes in Resting Heart Rate will make easily noticed changes. Not in the higher zones, so much, but definitely in the Fat Burn Zone calculation.

FitBit seems to value heart rate during sleep higher than heart rate during awake resting periods when calculating Resting Heart Rate. Which in my mind is foolish. If I kick off my comforter in the night I will cool down and my heart rate will go down. If I don't and my body temperature goes up my heart rate also goes up. If I am warm enough that I actually perspire it really goes up - and so does my resting heart rate.

I am including an image of a spreadsheet calculation of my zones as FitBit calculates them for when I was 68 and now when I am 69. Also shown is for a 35 year old turned 36 and the changes of resting heart rates when the resting heart rate goes from 63 to 70 bpm. A change in resting heart rate of seven bpm drives a change in the start of Fat Burn of four to five bpm.

Getting one year older barely makes a difference in each of the resting heart rate levels. It is the resting heart rate that really drives the changes.

I hope this either explains what is happening or at least doesn't confused you to much - I have a tendency to overthink "stuff" - it's the geek in me.

Good luck and welcome to the boards.