A tale of two commutes.
Aiming for zone 1 (Seiler 3 zone model), 135 bpm, watts who knows because I don't know my FTP yet.
Morning averaged spot on 135 bpm, power too low to mention. Felt great.
Afternoon felt fine enough, but my HR was jacked. Just rolling out of the office I was already at 130. Couldn't get it below like 140 no matter what, even sitting at lights. Averaged 158 bpm or something. Power and RPE didn't match that HR at all. Not sure if it was heat, or stress of not great traffic, or having ridden already in the day. I was nose breathing, felt fine, my heart was just going crazy though.