[dilyevsky]

If you’re training regularly 80-85% is nowhere near where your lungs burn - that’s like below 165bpm for most people

[canucker2016]

80-85% max heart rate is tempo pace - people suggest it's around the pace that one can hold for one hour

[dilyevsky]

Most runners i follow on strava and myself can sustain 85% hr over entire marathon race (with nutrition). It hurts after a while but it’s quite doable