Time Accumulated at VO2 Max (or +90% MaxHR)


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

40/20s (3 blocks of 12 @120%. I think it might have been hot on this day.)
1205 seconds above 90% HRmax

Shortoff +4 (9x3min @ 120% with 3min rests, in 3 blocks of 3. NB this is a 90 minute session)
1256 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.


Great data.

Can I ask what way you calculated 90% of HRmax?

My understanding is that it should be HR90 = HRrest + (HRmax - HRrest) x 0.9



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.


Do you know what your resting heart rate is?





48 + (175-48) x 0.9 = 162

rather than

175 x 0.9 = 158

Not that much difference really but I suspect it probably reduces the time >90%HRmax in the longer intervals.


I’ve posted these in other topics but it’s useful to have them both here.

Here is a link ti Seiler’s paper “Adaptations to aerobic interval training: Interactive effects of exercise intensity and total work duration” which is the research which defines the 4 x 8 minute protocol.

This is the presentation by Prof. Bent Rønnestad which highlights the study into the 2:1 shorter intervals.

Unfortunately the paper isn’t freely available.



I’ll run that number on the same sessions and report back when I get chance…


Why not use the V02 max summary at the end of each workout in TR/career. Maybe not based on HR but still a consistent metric and easy to measure


Those are some tough sessions!:muscle:

Are the first two custom workouts?


Yes, just built them up in Workout Creator.


OK, so when I check how long I spent on each session above 90% of my resting to maxHR range (as defined by @themagicspanner above), I get…

40/20s = 316 seconds above 162bpm
Shortoff+4 = 760 seconds above 162bpm
5x5min @112% = 774 seconds above 162bpm

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.

Catch 22 on VO2 work

Good stuff.

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.



How did you find out the seconds over a certain figure?


If you email the scientist directly, they are usually happy to send the paper pdf to you for free.

Scientific journals charge you for access. But they don’t stop scientists sharing the papers.



90% of Max HR is a guideline, but not a good prescriptive measure.

For example, my LTHR is 92% of Max HR and I can regularly hold that for an hour.

A better way would be to look time in VO2 max power and then subtract 20-30 seconds for each interval


I don’t think that’s correct - my understanding was that he was talking about using efforts of 3 to 4 minutes to elicit max heart rate.



I’ll have a another listen


Yes I think you are correct -and it makes a lot more sense. I’ll delete the post so as not to confuse anyone


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.