Auto update heart rate zones not working

This is not a bug as far as I can tell. It is a limitation of how they set the max heart rate. I believe Apple doesnt clearly explain how they determine max heart rate & thus the heart rate zones.

The following is based on my observations after noting issues with incorrect figures for my personal situation.

Resting Heart Rate - Updates monthly & is based on your actual data average for the last month.

Max Heart Rate - Updates monthly as needed ONLY based on your birthday, so it changes once per year. It does NOT use your exercise data. It only uses a standard max heart rate formula for determining an estimated max heart rate based in your age. For me, it is clear it used the Tanaka formula, which is for 40+ years old, and went down 1 bpm after a birthday.

After my birthday, it set my max at 172 bpm for 51 years old, down from 173 bpm.

I knew this was not accurate when I hit 179 bpm doing indoor cycling last year. Then when I hit 197 bpm doing an all-out running session, I knew max of 172 bpm was seriously wrong, and thus my heart rate zones were seriously wrong.

To workaround this limitation, I used a third party heart rate zone calculator based on my current resting heart rate & 197 bpm max & manually set my heart rate zones in the watch.

I sent Apple feedback that this is a serious limitation for some people and they need to alternately use actual exercise data for max heart rate when you can clearly demonstrate exceeding the one set by a formula using your birthday.

You can report bugs here https://apple.com/feedback

The OS dropdown is bound to be out of date so put your OS version in the problem text box

Hello Atonality,

Thanks for reaching out to Apple Support Communities. We see you have some questions about your Apple Watch and the tracking not working with your heart, and we'd like to help. From here, we'd recommend calibrating your device again, to see if this helps with what you're seeing: Calibrate your Apple Watch for improved Workout and Activity accuracy - Apple Support

Let us know if this helps.

Regards.

Generic questions get generic answers.

As you are someone who takes workouts seriously you should set your heart rate zones manually, This is too important a subject to let Watch do it. Do it in conjunction with your foctir or trainer if necessary. Know uiur own heart.

also

How to create a heart rate notification w… - Apple Community

Next time you LYAO start a mixed cardio workout.

Advice is free, you don't need to accept it, but being gracious does not cost anything.