Max HR improving, what's going on physiologically?

[bbarrera]

@cartsman

And if you want to know your max HR then I find the best way is a short punchy race like a crit (real or in Zwift). I can pretty much guarantee that my max HR in any race under an hour finishing in any kind of sprint will be within a couple of bpm of the highest I’ve seen in the last few years.

or similar, a fast group ride where you are on the limit for long stretches and then sprint. Works for me every time.

And Lactate Threshold Heart Rate (LTHR) is pretty darn stable and far better for setting zones. Used this guide - Joe Friel's Quick Guide to Setting Zones | TrainingPeaks when I got started in 2016 and my LTHR has been the same year in and year out. And the HR zones based off that are also reliable, except in unusual circumstances like going from riding in 60s and then flying somewhere and riding in 95-100 degree heat. Then all bets are off and HR is going to go crazy while trying to support sweat/cooling.