Originally Posted by
531Aussie
I posted this somewhere before, but I think it's worth another look, even though it's more about zone 1 than zone 2.
This guy's top of Z1 (75% max HR) puts me at about 190 Watts on my trainer, which is 73% of my FTP and near the top of Joe Friel's Z2. It would put me well into Z3 on smart phone apps designed to appeal to vanity.
Heaven only knows what 75% max HR implies for a world class athlete with 440 W FTP, but it's bloody obvious that it involves quite a lot of respiration, metabolism and power.
Thanks for posting. Interesting stuff.