Interesting video of VO2master during Billat 30/30 workout

Nothing gets this forum jazzed up like a little VO2max discussion! This guys has some interesting data on his youtube channel. He uses perfpro, moxy, and vo2master during workouts and lets us see the real time data. (for those that are unfamiliar, moxy is a NIRS device that measures blood oxygen content, among other things)

In this video he does the first 6 minutes of a Billat 30/30 workout. We get to see power, heart rate, respiration, tidal volume, smo2, VO2, cadence, all sorts of fun stuff! He states that his VO2max is 65. So it’s kind of interesting to note that during the first 6 minutes of the 30/30 workout his VO2max is only at or above 90% for about 16 seconds. Most of that time is accumulated in the 2nd 30/30. By the time he gets to the 5th 30/30 there are 0 accumulated seconds at or above 90% VO2max. (interesting that oxygen consumption seems to be reduced after some priming period, right?)

It’s interesting that he’s doing the Billat 30/30 workout because Billat herself has published work on a much better VO2max workout. I made a detailed post regarding this protocol here:

The main point I want to make is that Billat herself crafted an interval during which participants rode for many MINUTES at not just greater than 90% of VO2max but RIGHT AT VO2max. In fact, it was most interesting that the youtube data was for about 6 minutes of 30/30s…note from the Billat data I posted that the rider accumulated 90 to 120 seconds essentially right at VO2max in the first four minutes of the interval…and then essentially held that VO2 for another 15 minutes. (I’ll post the image again below)

So I’ll say it again: 30/30 intervals feel easier because the are in fact easier. Although I’m convinced they provide some VO2max adaptation, I think you can do better with a hard start VO2max workout.



Your post leads to me to the question…how about combining hard start VO2max with short/short like 30/30 (or better 30/15)?
So hard start until the 5min point in the graph and then followed by a short/short part instead of constantly keeping around LT2.
Might be some nice variation. Don’t know if there are studies using that variation.

What % ftp are these intervals ridden at (30/30s)?

Good question! You can see on the readout that it’s 275. In the perfpro display window that is immediately to the left of his camera video…in the upper right hand corner of that display there is a blue number surrounded buy an up arrow and a down arrow. That’s FTP…or critical power in this case.

But I think he is legit doing Billat intervals. Meaning the work rate of the 30 second intervals is really the minimum workrate that elicits VO2max. (and not some percentage of FTP) So that takes the guess workout out of it…one of the luxuries you get when you’ve got a piece of kit like the VO2master.

I’ve never thought to try something like that but it’s an intriguing idea.

This is the very reasons why I don’t do pure 30/30s or similar. Looking at my heart rate I can see how long it takes to bring it up. For the first set it takes about 6 intervals as well. Not good for the head.

I rather do longer intervals initially and move to these intermittent sets. This was inspired by Vaccari et al. (2020). Time at target heart rate gets a much nicer response.

This is a super interesting bit of evidence supporting this point.

Anecdotally I’ve found multiple repeated VO2Max intervals of short duration with short ‘rest’ in between to FEEL easier than the 3 minute (or longer) intervals of alternative sessions. This is even though in many cases the level of power is at a lower % relatively speaking, for the longer intervals.

I’d be interested to see the same data feedback for a 3 to 4 minute interval length repeated with 2 minute breaks (for example) to see how much time gets spent in that magic zone comparatively.

I agree when we’re talking about training but I do think that 30/30s and similar format sets have a benefit when placed into a racing context.

If you can go hard again and again with little recovery, you’re a real asset in a small breakaway group.

Whilst not as physically demanding, knowing that you’ve got 20-25 bullets in your gun is real mental boost.


Agree! If the goal is to accumulate time at the work rate then 30/30s are probably better…and I think that’s the #1 counter argument here: the primary adaptation isn’t triggered by maximal oxygen consumption but by muscle ‘time under tension’. And if this is your operating theory maybe the TR ‘float’ workouts would be more specific to your goal.

The other thing to really consider is whether working at 100% VO2max really drives (overall) more adaptation. Sort of like riding at 100% threshold might not be as good as riding at sweetspot. If you only have less than an hour to train riding at 100% threshold is probably better but over the course of days/weeks you can sure accumulate a lot more training time at sweetspot! So maybe training at 85% VO2max is just a little less training stimulus than an equal amount of time riding at 100% VO2max…but you can ride 5x more at 85% than 100%. Dunno.


I think whether short-short intervals work as vo2max intervals might have something to do with your FRC to vo2max ratio, or your power curve in that region, and also with how quickly you recover (which might depend more on your FTP).

I also think that whether you should do 30-30s, 20-40s, or 40-20s also depends on those factors. (Isn’t it funny how everyone will say they do 40/20s?).

To me, they work better as “repeated anaerobic” intervals, that, once my anaerobic capacity has run out, turn into vo2max work.

SS vs threshold is a very pertinent comparison in my view. It’s not always about doing the theoretical “best” workout on any given day, but also about workout compliance and recovery. I find 30/30s really useful during phases of base or maintenance when I want to touch on that power zone (especially as an older rider) but don’t want to build my week around dealing with either the mental or physical stress of suffering through long VO2 intervals. Especially as those phases often coincide with times of year when I’m riding indoors a lot - long VO2 intervals indoors are particularly unpleasant!

Flip side is that I don’t feel like 30/30s really prepare me for races. So as I start building towards a race I’ll do longer intervals but I’ll also get off the trainer and go do them outside where I have the motivation of a group and/or a hill to get them done instead of just staring at a screen watching the seconds tick slooooowly by. If solo I normally do a series of closely spaced hills of ~3-7 minutes each, and I’ll often do them as hard start. I.e. set off a bit harder than I can maintain to get the HR and breathing up quickly, then hang on as best I can with the power slowly dropping (pretty much the opposite of how to ride a hill if you’re in a race or going for a PR). Or do some race training with a group where we basically just hammer it on a quiet loop of road somewhere, riding fast with frequent attacks until our legs fall off. I find these incredibly good preparation for a race, and far more beneficial than you would guess just from the power numbers. As while the power may be a bit all over the place, HR and breathing are right up there for the duration, so I would guess that oxygen consumption is at or pretty close to VO2 max for much of it.

BIllat’s 30-30s were done with runners and not cyclists.

The oxygen kinetics of the two sports are very different, and what elicits VO2 in one does not necessarily do that in another.

30-15, ok maybe. For cycling, more like 30-10, or 30-5. The VO2 kinetics are closer to swimming than running, so the work-rest intervals need to be more like a swimmer would do. short

30-30s on the bike are good for “punch and recover,” which you need in races, but they’re not really VO2 work unless you’re new to cycling.

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Are you absolutely certain that there is not one more Billat study refuting this notion? :joy: :rofl: She has done so much interesting work.

“VO2 max (expressed in ml min-1 kg-1) was significantly different between all sports except between cycling and running (p < 0.05).”

This was a result that surprised me, btw, but also the result is based on TTE at VO2max. The absolute VO2max between running/cycling is certainly different. Remember, though, that Billat intervals are done at the minimum power that elicits VO2max…or velocity in the case of running…so regardless of the absolute VO2max the relative effort should be similar. :man_shrugging:

did Billat do a study of 30-30s with cyclists?

The caveat that the 30-30 protocol does not work as well for cyclists as for runners is something that has been mentioned a number of times on the forum – as coming from coaches. I don’t want to take the time to use the search function, but we can probably trace down those posts.

One thing to note is that he’s using Xert and he’s targeting the yellow zone. I don’t know if you’ve used Xert, but the colors change during the workout. What was Yellow early on, has become Red as his MPA drops. So, if targeting the power range that Xert is telling you (he is targeting the yellow range), then yes, he will be at a lower peak wattage, and it will continue to drop for the duration of the workout. The yellow zone squeezes and shrinks.

and if memory serves me correctly, the main oxygen demand difference between running 30-30s and cycling 30-30s stems from the difference in inertia. The energy (and thus oxygen) demand of the acceleration phase is greater for runners because they’re going from a slow trot/walk at the start, as opposed to a cyclist who can freewheel or soft pedal before having to hit the next 30. If a cyclists could somehow do these 30-30s on a, say, 4-5% grade (if they start each 30 rolling), or from a track stand start on the flat, it would start to be more like what the runner experiences.

Yeah that’s a good point. Didn’t know this about Xert. If I go back and watch the power during intervals carefully, the 3rd interval does seem to be at a higher work rate.

Little different experience from @SpareCycles:

My personal experience due my profile with short shorts is that they are completely pointless in terms of vo2 max gains (start hard and pedal till you puke and repeat is my goto workout and it works for me) but they are quite ok to put some stress to the body and add some sharpness after some steady work block.

In terms of breathing - I cannot sprint and I cannot put enough power through the on portion (when I do 15/15 I can only push around 150% of my FTP, I completely lack of snap), my HR is around 95% at the end of 15min block but my breathing is only slightly elevated, like during hard threshold workout). I have tried, they do nothing for my vo2 max, when 6 steady state intervals always lead to some improvement.

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This is what I like doing after I reading similar stuff some months ago:

These are almost 13 x 30/15s: a hard start of 1:15 at 135% ftp, followed by 2x30/15s at a lower 120%ftp to “recover” and continue the other 8x 30/15s at 135% ftp.