If you’re in decent shape, the only way to find your real maximum heart rate is to do intervals and SEE it. My max seems to be going down …from 170. (the 220 minus your age formula would give me 146 but that’s clearly too low.) A drop makes sense, but what is it today…

I thought I’d check this morning, early, climbing up Smuggler (a stiff climb out of town…about a half hour jaunt.)

Did warm up, Then to old 70-75% for a longish time. About 2/3 of the way up, hit it a bit….got to 140’s and climbing.
Jogged a bit at the end…saw 165 BPM at the top. THAT’S IT. MY CURRENT MAX – AT 8-9000 FT – IS 165.
Usually, we are as much as 9% lower in Aspen as at sea level so my sea level Max may still be around 170. We’ll see. But 165 is fine.
Hey…don’t try this at home unless your doc says you’re ready and you are in decent shape. Don’t want any sudden deaths in the YNY family.