I have had to start monitoring my heart rate when I run. I used to run two half marathons and a full every year, but since Covid, I've had struggles. I don't stop and take a rest, but I will walk until my HR recovers back to aerobic. An I must admit that I am doing this without my doctor's advice, I just felt like that was going to be what I was going to have to do to continue 5Ks. Riding hasn't seemed to be as impacted as much as running, because I only do about a 14-16 mph pace for an hour or so these days. If I do longer rides, it is about 10 mph on the MUP.

Now the do I suggest not as I do comment. Ask your doctor for a strategy to continue to ride. And make sure whatever you are measuring HR with during a ride is visible and halfway trustworthy.