Starting a new thread as this topic has come up in a number of different threads, mostly discussing polarised training, vo2 sessions, or Seiler intervals.
One metric for measuring work is not the amount of time at a particular power, but the amount of time accumulated over a certain heart rate - i.e. the best approximation of time at actual vo2 max.
So I took a few recent rides, and added up the number of seconds spent above 90% of my max heart rate. I picked ones that were a struggle to finish, but have a variety of interval lengths.
[Disclaimer - heart rate massively subject to variability; I can’t guarantee the temperature was the same on all these rides, or that I was equally rested]
5x5mins @ 112% w/3min rests (was supposed to be 6x5 but 5 was enough!)
1020 seconds above 90% HRmax
Would be interested to see what other people can come up with. I haven’t done the Seiler 4x8min intervals yet but I’ll make that comparison when I come to it.
Just literally that. 90% of 175 which is the highest I’ve ever reached.
I’ve heard about using the range between HRrest and HRmax, but just wanted to keep it simple. My main purpose was to compare different types of session to see if there were any that had significantly more or less time accumulated at a high HR.
Which suggests that the on/off intervals aren’t quite as effective at pushing your body into that highest heart rate zone as longer sustained intervals.
More research / data needed, obviously.
The Rønnestad presentation camparing the two protocols did show some subjects didn’t reach a high percentage of VO2max with the 2:1 intervals. Clearly they weren’t effective for those athletes and may not be effective for you.
Max heart rate is an interesting question. Would you necessarily have a fixed, permanent max? I’ve had days when I’ve gone RPE10 for 3-5min and maxed out at 195bpm, and times when I’ve held over 200bpm. I’ve seen 30-second bouts in my data where I’ve held 220bpm. If I do a kilo TT, I hit +190bpm within 30 seconds or less, and pretty sure I’m at my max by the end (~1:13).
My sense is that heart rate does not directly correlate to eliciting VO2max, but it’s a “pretty good” indicator.