Anatomy of the 15 minute VO2max interval

Interesting stuff from what many would consider the creator of 30/30.

I always say the most efficient way to accumulate minutes at VO2max is a hard start VO2max interval where you manually dial back power to maintain VO2max. Here’s part of the data that gives me that idea. Presenting the 15 minute VO2max interval:


There are two VO2max intervals on this chart. The light gray data points are what I’m talking about. Boxes are VO2 data & diamonds are power data. pLT is lactate threshold power…so LT2 in this case is 300W. Note the rider is under lactate threshold for most of the interval but still working at what this research team considered VO2max.

Here is the 20 minute VO2max interval (it makes me a little nauseated just to type that):


Again, a lot of this interval was at LT2 but still enough to maintain VO2max.

In these cases, the ‘hard start’ power level was set to what each athlete tested as the minimum power required to elicit VO2max. It’s interesting to note that power was, generally, quite a bit higher than what most would consider ‘VO2max’. I would have said VO2max was about 120% of FTP but it was much higher than that in this study.


Sometimes I have to remind myself that VO2max is a physiologic condition, not an absolute power level. :wink: For sure cranking away at 120% of FTP is going to get you to a VO2max condition eventually. So maybe this is just splitting hairs.

Anyhow, these athletes were able to turn in some whopping VO2max intervals using this protocol. On average, over 15 minutes of work at VO2max. For a single interval. Efficient, for sure, but I’ll bet not fun.


The sustainability of VO2max: Effect of decreasing the workload


I’m having a hard time following what the protocol would be - I understand it will be slightly different for everyone though.

So you hard start at approx 135% of FTP on average, but for how long?
Then you bring down the power to around threshold and hold that power for the remaining portion of the interval ?

Can you link the study please?

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In this case Bilat used an incremental test & metabolic cart to find VO2max…then during the variable VO2max interval they used to metabolic cart to monitor VO2max real time & adjust power to keep the athlete there. Not practical for most of us!

However, one of the things that really caught my eye about this study is how much many of their data points match up with what we found out doing VO2max while watching NIRS observations of blood oxygen & heart rate. Based on that approach you won’t be far off if you just do a hard start 150% of FTP for 90 seconds then back off the power to maintain 92% of HRmax…always remembering that it’s gonna take your heart about 30s to respond to power changes.

But I don’t think I could go on like that for 15 minutes!


The sustainability of VO2max: Effect of decreasing the workload

Veronique Bilat

Full paper for nerds like me that read the whole thing
billatThesustainabilityofVO2maxeffectofdecreasingtheworkload.pdf (806.5 KB)


Some discussion about it in a thread from May 2019:

Is it just me, or are the X-Axis’ labelled incorrectly? It says Time (s), but is in minutes, no?

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Wouldn’t you be able to approximate when you’re in vo2 territory, based on your breathing rate?

Yikes! I’m not even sure I could do 150% of FTP for 90 seconds on the trainer - I could possibility outside. It appears you are giving the extreme example though, as I imagine it wouldn’t take that kind of effort and duration for the vast majority of people to reach Vo2max. It would definitely be painful to hold 93% of max hr after that! Or maybe not? I imagine HR will be elevated for quite some time after the 90 second period, and you power will definitely degrade.

In summary, it sounds like a max 90 second effort and a slow death for approximately 13.5 minutes.

Ha! Yeah! It’s hard. What I found by watching my own blood O2 was that 90s @ 150% was required only for the first interval. On the next interval I would be @ VO2max with only 60s @150%…then drop to something like 105% to 110% of FTP for the next 3.5 minutes & adjust power as required to keep HR @ or around 92% of HRmax.

So only the first interval is 90s @150% followed by 3 minutes @ 115%.

I don’t think I could maintain that sort of interval for 15 minutes either. But, maybe properly motivated I could.

Looks like! Says seconds in the axis title but should be minutes, I guess.

So basically as hard as you can to get your heart rate up quickly to about 95%max then reduce power not letting your heart rate drop below 92% of max, then just see how long you can stay there.

I’ve never tried to hold it as long as I could…but, for example:


Sounds delightful! I can see everyone heading for Workout Creator…

Non-custom pain is available off the shelf with Rattlesnake.


don’t mean to sound nit picky… but I got to wonder how this slipped by the authors, the journal editor AND the reviewers… I know for sure my supervisor would have slaughtered me :joy: :joy:

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lol there is even a +2 version… I’m dying just looking at it :nauseated_face:

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The Germans Gerschler and Reindall in the 30s or Emil Zatopek ? :grinning:

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Wonder how often that one gets completed. Looks brutal to me and I do 40/20’s with some frequency.