Originally Posted by
69chevy
I'm either a freak of nature, a cardiac time bomb, or that isn't always true.
80% of my max heart rate (191) is 152.8 bpm. 191 is the highest I've ever recorded and it was a full effort up a 10% grade.
Literature says that zone 5 is only sustainable in short bursts (less than a minute).
I sustained what literature calls my zone 5 for over an hour.
I'll admit I'm a HR noob, but can you enlighten me. (OP... If you don't want side discussions, I'll take this elsewhere.)
Why do you think that 80% of MHR is an interesting number? That's about the top of Friel's Z2. I should hope you could sustain that for over an hour. I've averaged an 80% HR on 3 hour group rides. For most people, Z5 starts at 89%-92% of MHR. However that may be, only testing can tell you your lactate threshold which is the beginning of Z5.
Information about a common LTHR field test can be found here:
CTS Field Test: Why two 8-minute efforts instead of one 20-minute effort? - CTS
I believe you are incorrect about what the literature says about Z5 interval limits.