Workouts Heart Rate Zone - apparent bug calculating heart rate zones incorrectly

[Ross111]

I'm new to Apple Watch, and have used workouts for indoor cycling a few times.

I noticed a shift in the heart rate zones the last week or two, and it appears to be a bug on WatchOS 56.3 (23S620).

Here's what workout settings says about automatically set zones:

Resting: 60 BPM
Maximum 173 BPM
Zone 1: Below 126 (60%) <- should be Below 104
Zone 2: 127-138 (60-70%) <- should be 104-121
Zone 3: 139-149 (70-80%) <- should be 122-138
Zone 4: 150-160 (80-90%) <- should be 139-156
Zone 5: Above 160 (90%) <- should be 157+

Of course, if working out by zones, this would push folks closer to their max heart rate than they should be.

 

[Madonepro]

Of course, if working out by zones, this would push folks closer to their max heart rate than they should be.

First you should know, that Apple uses the Heart Rate reserve method of calculating zones. https://www.topendsports.com/fitness/karvonen-formula-calculator.htm

I suggest, and it's what I do, is to Apple Watch App/Workout/Heart Rate and select manual, and input your max hr yourself, and then set the zones to what you feel is accurate. Highly recommend you read this guide - https://www.trainingpeaks.com/learn/articles/joe-friel-s-quick-guide-to-setting-zones/

 

[Ross111]

First you should know, that Apple uses the Heart Rate reserve method of calculating zones. https://www.topendsports.com/fitness/karvonen-formula-calculator.htm

Thanks for that education!

I didn't expect that, given it shows only % and max heart rate on the screen, but that would make more sense. Doesn't explain why all my zones changed recently, but maybe it learned something new about me. How accepted in the fitness community that Apple Watch's methodology gives a sound max heart rate?

I need to go read up more on what that article mentions about measuring max heart rate, as given some knee and foot issues I'm going through currently, hard to do something like a time trial.

 

[Madonepro]

Thanks for that education!

I didn't expect that, given it shows only % and max heart rate on the screen, but that would make more sense. Doesn't explain why all my zones changed recently, but maybe it learned something new about me. How accepted in the fitness community that Apple Watch's methodology gives a sound max heart rate?

I need to go read up more on what that article mentions about measuring max heart rate, as given some knee and foot issues I'm going through currently, hard to do something like a time trial.

Max HR is simply the number, the watch has seen you get to, and also based on your 220 minus your age, which is unreliable. Effectively your Lactate Threshold kicks in, around the 92% of maxhr mark, so when you can run, LT is where it's uncomfortably hard, but just about sustainable. Then you do some math, and work your Max HR, by dividing LT by % i.e. LT/92 = MaxHR