Max Heart rate ridiculously high

I’m an overweight 59 year old slow runner - 13 min/mile with a VO2 max of 38 …. but Garmin thinks my max heart rate is 203 (autodetect) which is ludicrous! Using the old formula I’d guess closer to 160 would be more realistic . It’s been like this for months. It means none of my efforts ever really get recognised as such. I wear my watch 24/7 so what am I doing that causes this ? My runs are mainly 30-60 minutes maybe a couple of short walk beaks and I do a lot of walk activities. 

  • The 220-age is also garbage for most people.  

    You need to actually find out your max heart rate.  You'll never hit max on steady state runs or walks.  The only real way are thinks like max effort uphill sprint interval repeats etc.

    The only real way to find out your max heart rate is to something, really hard that will approach it.

  • I had a similar issue when I got the watch ~2,5 years ago.
    What I had to do is to set HRmax manually to a more probable value, leave it as manual for a few weeks. These few weeks were necessary for the watch to realize it's mistake. Then I reenabled auto detection, and it's been working ever since.