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

Agree. 90% may be too low to put you into VO2 max. I can hold 90% of max HR for several hours during MTB races.

I think what HR corresponds to VO2max probably depends on what your limiter is. For me, it’s my heart, so for me to reach VO2max, I need to be close to max HR.

If your muscles’ ability to utilize oxygen is underdeveloped relative to the ability of your cardio system to supply oxygen, then VO2max HR might well be 90% of max.

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From Seiler’s paper (referencing another paper by himself):

Direct Observations demonstrate that world class athletes may accumulate ~ 15-30 minutes of work at 95% maximal heart rate, ~ 40-60 minutes at 90%, or 60-90 minutes at 85% of HRmax during interval training sessions at these respective intensities.

Without reading that paper (which I may get round to) it’s hard to know exactly what that relates to.

I wonder what it means if a non world-class athlete (I’m making an assumption here) can hold these percentages for longer?

Is that just specific to an individual, or is it related to the amount of training or performance level of the athlete?


Several of the specialty plans–rolling road race, climbing road race, criterium, short-track XC come to mind–feature copious sessions with varied intervals well over threshold. Criterium, not surprisingly, errs towards the burst-ier side of things but the short+hard efforts aren’t absent from other plans. The n=1 results on this forum I’ve seen from fitness increase from the Criterium plan was considerable, around 8% (from like 346 -> 374). I don’t imagine everyone would respond the same, but I would say that trying to find a few distinct interval structures will be more maddening than productive, and that the specialty plans offered by TR are excellent.

The basic approach of three weeks with ~3 hard workouts and a mix of other riding (err towards easier) followed by a dedicated recovery week seems like the most useful way of training for most everyone. Rather than worry about the nuances of what specific stress to incur, I focus on ensuring that I’m getting enough stress and enough recovery in the first place.

Doesn’t HRmax decease with increasing fitness?

With a lot of painstaking moving of the mouse over my heart rate line in Training Peaks, and then a lot of adding up.
Unfortunately you can’t create a +162 HR zone and apply it retroactively to old workouts. If I was planning it ahead I would simply do that and then look at “time in zones”.

Yes, you can. Change the zones and then go into the workout and hit recalculate.


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Is that a fair way to analyse a 40/20 kind of session though? Because subtracting that 20-30 seconds suggests that each interval starts at a relatively rested state, whereas in the latter part of a 40/20 block, the 20sec rest interval is barely any recovery at all.

I take your point that people’s %maxHR at different intensities may differ. Perhaps it’s just a matter of finding your own baseline from experimentation, then use that to help you see which workouts push you hardest.

That might have saved me a bit of time. Maybe I’ll go in and see if my own manual calculations were accurate…

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No, it doesn’t work well for 40/20s. I’m mostly using that as a hack for EWMA power (which you can look at in WKO4), which is a decent proxy for the physiological response. In general if you want to use short power intervals for maximizing time@VO2max, they have to be harder than what you would use in a longer interval.

Example of a few workouts:

30/30s @125% (5 sets of 5, Sleeping Beauty)
4 mins above 90% of VO2Max

20/10s @ 150% (Tabata-type protocol, could only do 2 sets)
7 minutes above 90% of VO2Max

Nunburnholme (6x4 @110%, bailed after 4 intervals)
11 minutes above 90% of VO2Max


How does WKO4 calculate “time above x% of vo2 max”? Is it HR based?

It’s all power based. They have a formula to calculate VO2Max power based on their power-duration model.

IMO I wouldn’t use HR as a VO2max proxy. It’s too variable and the lag is too significant depending on fatigue/hydration/etc.

You also don’t really need to get too complicated. For steady state intervals of 2, 3, 4, and 5 minutes, tracking time in the VO2Max power zone will give you a good sense of whether you are improving or not. If you are increasing the length of intervals and increasing TiZ, you are getting stronger.

This EWMA/90% stuff is marginal gains. If you are nailing the foundations and you have plateaued, then start looking at the deeper metrics.


I realise now why I seemed to find the VO2max" workouts I have been doing relatively easy with respect to SS ones. I have not been spending anywhere near enough time in the actual VO2max zone. You live & learn

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I emailed him at the weekend and got the paper first thing this morning.