Is it really a VO2max workout if you don't get anywhere near HRmax?

Last night I did a “stretch” VO2max workout, and I didn’t even hit my LTHR.

I would say that I felt like I was getting pretty good stroke volume, since each beat felt pretty powerful.

Is it really a VO2max workout if you don’t get anywhere near HRmax, as long as stroke volume and/or VO2 is relatively high?

Or was the workout just too easy? I marked it as “moderate.”

The “on” intervals felt like power I could do for more than five minutes without a problem.

Your Progression Level has likely not adjusted yet. Either keep marking V02 rides as easy (and the system will auto-adjust) or select a much higher PL (by choosing an alternate workout). You’ll know once you’re getting to the right level.

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I wouldn’t say it was “easy” in absolute terms, but it was easy for a VO2max workout.
I think Nate said not to overthink the ratings, so I tend to go by absolute difficulty, maybe with a slight consideration for relative difficulty.

This was actually an alternate workout of a slightly higher level (I needed to burn 400 more calories…lol).

I think you don’t need to hit HRmax, but at least enough above LTHR (on long enough intervals).

it was 30\30s, but only ~115% of FTP…

If you didn’t reach LTHR with 30/30s 115% on a stretch workout, my humble opinion is that you may need a FTP update (or adjust your AT feedback.),maybe I’m wrong.

I just updated FTP (via AI) last week, but my VO2 max level was basically on the floor because my plan didn’t include any VO2max in the last few weeks. So it was probably that.

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The basic idea behind 30/30s or 40/20s or 30/15s is something like this… Lets make it really simple, say a 250W ftp and doing 3x3-min at 120% is your limit. That is doing 3 minutes at 300W, and after 3 sets its 9 minutes at 300W.

Now you do 30/30s, and lets make it 3 sets of 6x30-sec on / 30-sec off. However instead of doing 300W, you can repeat 350W (140% FTP) for each of the 30-sec. Each set is 3 minutes at 350W, and 9 minutes total at 350W.

Different intervals, however in this simple example you accumulated 9 minutes at 300W with one vo2max format (3x3-min), and 350W with the other vo2max format (3 sets of 6x30-sec/30-sec). More power with the 30/30s.

Some discussion on adaptations here: Micro-Burst Intervals: The Most Effective HIIT for Increasing Power and VO2Max

In any case, vo2max work is suppose to be done with max repeatable power, instead of constraining it with erg and % ftp. So it has nothing to do with an ftp update, unless you determine max repeatable power in advance, and then reverse that into a %ftp if you insist on using erg.


So there are a few issues:

  1. % of FTP is a bad way to go about this prescription. Too many degrees of freedom.

  2. 30/30 workouts are ideally better going as hard as you can within reason.

  3. Idk how TR handles people that have a big W’.


I have the same problem, i never hit vo2 heartrate doing short intervals. I heard Mattias Reck a trainer for Trek Segafredo saying he recommended using the 2 min maxpower for 40-20 and 30/30. Im going to try that when i do my next 30/30s.

what about just going until you hit 90-95% max HR…get in that range and should be good!

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Then they are not hard enough. You want to try and maintain the maximum power you can sustain across all the intervals. Some days this may be 120% of FTP, other days 123% of FTP, other days 116% of FTP. You may find you can hold 130% of FTP across the intervals. You can feel you’re way into what level you can sustain in the first set, provided you have broken free of using ERG for these.

When I’m in shape 30/30s aren’t enough to hit the right HR zone, the recovery is too long. 30/20 or 30/15 are a lot more likely to work. Or just go hard for 5-10 minutes, rest and repeat!

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I’m no expert but I think if you were gasping for air it was a fair reflection of your current VO2max but if its not even near your LTHRT it not your real vo2max. Sometimes for the first few short VO2max intervals I’m not near it either but after a few sets I’ll be over 90% MHR and if I can before a big recovery I spin up as much as I can in the last interval of a block which might push me over 95%.

My HR always seems to be a zone or 2 below my Power zone. My legs feel like I’m in the right zone but my HR doesn’t. I dunno…

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I’ll post this thought and see where it leads.

VO2 Max is comprised of two elements

  • How much oxygen can you deliver to the working muscles?

  • How much of the delivered oxygen are the working muscles able to extract?

VO2 Max is about the maximum rate of oxygen you can utilise; which can be achieved through a combination of central and peripheral adaptions.

Then arises the questions, which workout structures best drive which adaptions? Does the HR need to reach a high percentage to trigger the signalling, or can a high delta in oxygen demand vs. delivery during the on interval be equally effective?


I’d wager very few people would actually be getting to VO2 max at this intensity. If you’re doing 1:1 work:rest on short intervals most people will need a much higher % of FTP

As others have said short intervals should probably be done more by RPE than FTP %. However, if you want to challenge yourself on short intervals while using FTP % you should change the ratio or increase the FTP %. Find a workout that is 30:20, 30:15, or 30:10. Or stick with 30:30 and up at 135%. Adjust until you find the ratio or % that actually taxes you

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If you’re more endurance oriented, a similar level, longer workout, is often going to feel easier for you. This is the case for me at least. I have heard Jonathan say that shorter workouts are harder in the podcast, and I find this to be true- when I am short of time and cut workout duration using alternates, but keep the level the same, I am more likely to fail a workout.

Try a similar or perhaps slightly high level shorter workout and see how it feels, but as stated, AI will find the right levels for you if you keep rating VO2 work as simply “hard” or lower. I avoid easy unless it was truly easy, because AI will ramp levels really fast in those cases.

The problem is what is named a “VO2max” workout. Basic endurance training raises VO2max but we generally don’t call it a VO2max.

The other confusion comes with the classic 5-6-7 zone models where zone 5 is labeled “VO2max”. It’s a power, not necessarily time at actual VO2max.

My understanding is that the Billat short/short intervals are designed to allow more work at lower lactate levels. Is one hitting physiological VO2max?

I read recently (or maybe it was a Fasttalk podcast) that even in a classic 5 minute VO2max effort (huffing and puffing at the end), the rider is only hitting VO2max towards the end of the effort.


Pretty sure I heard Seiler say his prescription was 90% of MHR. More than that was unnecessarily hard on the regular.