Charge 5 app fitness zones just hugely wrong

[Dhruc]

My zones on my fitbit app are entirely incorrect. I thought it was a bug when I tried to setup custom zones, but the maths is just entirely wrong.

Im 36 and the app is stating that my cardio zone starts at 120, which mathematically is just so wrong.

It's just randomly picked these zones, how can I fix it. Its driving me mental 

[Dhruc]

I'd add my resting heart rate is 52.

[SebWotan]

Hello @Dhruc 

In Settings for your device, on the App or dashboard, you can change your heart rare zone and make them custom.

[Dhruc]

Hi Seb, I can set the custom zones but how do I change the standard zones it has picked make sense? They are mathematically just so wrong.

[Dhruc]

I've worked it out. If you choose you maximum heart rate, it just randomly picks zones on the basis of no maths whatsoever. It's very random. I've managed to get it back to a sensible enough banding, although I'm liable to heave a heart attack before I ever get into peak, which it now expects me to do when my heart rate is 187. Whatever, I just need to make sure I'm sticking to fat burning at a sensible level (not between 97-119).

[SebWotan]

Choosing a customer Max HR will indeed change the zones. 

The zones are chosen according to a formula: fat burning is 0.4-06 of the available heart rate band + RHR,  cardio is 0.6-0.8 of the available heart rate band + RHR and peak is >0.8

The heart rate band is max heart rate - RHR, and Max HR is 220 - age. 

[LZeeW]

@Dhruc  The heart rate zones aren’t random.  Fitbit uses a formula that uses your age and resting heart rate.  The equations are described in this  Help article.   I hope this helps make sense when you see your Fitbit numbers.