Question: %VO2 max definition

I caught this 90% VO2 max magic threshold in a couple of threads. What does that mean in actionable metrics? And why is the relationship between VO2 max % and MHR % out of whack; in that 100% VO2 max is > MHR? I mean I guess it makes a sort of sense if I am thinking about anaerobic contributions or am I barking up the wrong tree here.

The fact is I am struggling to hit some of the projected HR zones ~95% MHR before the breathing and legs crap out of a given interval. HTFU?

Wrong tree.

Ignoring factors that would “artificially” elevate HR (e.g., heat stress), MHR and VO2max should occur essentially simultaneously.

At any intensity less than that, though, % of MHR will be higher than % of VO2max, because at rest you are at perhaps 25% of MHR, but only about 5% of VO2max.

Your experience with difficulty getting your HR up during intense intervals is quite common. It can be due to fatigue, insufficient motivation, poor pacing, etc. Lack of cycling-specific fitness can also play a role.

HTFU then…
Fatigue… possibly as I have been doing rather a lot of VO2Max attempts recently

Insufficient motivation… Maybe but unlikely; Gagged on the fourth interval yesterday when I was coming down from it @92% MHR. The last time that happened was at an 800m track race when I was 14 and going for the win (didn’t). All of them are having me gulping like a beached fish by the end.

Lack of cycling specific fitness… unlikely RHR at 40 for a 52 year old and the CTL in the high 70’s. Not outstanding but not useless. Lack of VO2 max work in the last two months for sure. I was mainly tempoing it.

Maybe I will back off and try em again later.

First question, how do you know your MHR is correct? Maybe it’s dropped a little and what you think is 95% is actually 98% - I wouldn’t want to go there repeatedly!

The other part…I’m not sure HR and VO2max are that correlated. For one, HR has other factors that influence it, there needs to be room for them to shift it up/down. And then VO2max has to do with oxygen transfer, when that is maxed out, there is no need for HR to keep increasing.

I don’t, but the estimate is 1 BPM off my recorded max for this season. So close enough for military work.

And I would agree with this but I would have thought that approaching MHR one would force some sort of correlation as there is by definition a hard limit there. I suppose the point is that I may not be able to approach that limit due to external factors, i.e. residual fatigue, and yet be still in the appropriate VO2 max regime?

I’d say yes - there is this study that showed that once you reached VO2max, you can back off a bit, and still stay there

I’m deffo not an expert in this though, hah!

That’s true I did read those… I guess I am struggling to find a metric to give me go/no-go criteria on the VO2 max zone reached. So I can hold at that.

Going till I puke seems counter productive as that’s the rest of the session blown as happened yesterday.

Yeah I agree. I can never decide if you actually need to go that hard. On one hand I think that most of these training effects happen on a continuum, so if you ease of little bit, you should still get nearly the same benefit. On the other hand there is this thing that when you want to progress anything “max”, you need to actually go “max” (like lifting power or a sprint) - but then you have to do it rested to be able to do it properly.

This is definitely NOT true for me. Unless by VO2max you mean some theoretical absolute maximum oxygen consumption that nobody can ever attain but is calculated in a spreadsheet. Anybody else have actual measurements of oxygen consumption compared to heart rate & can confirm refute this? Interested to know if my experience is similar or different from others.

Again, if we’re just talking about some non-practical theory…ha! Then we can bin the discussion. Doesn’t matter.

Well if the adaptations are just based on hitting the max then I have failed anyway as I was only at 92% max HR when I lost it. The other problem is that losing the lunch only happens when you come off the effort not during. So some discriminator for pacing up there is needed regardless of whether you are targeting a true max or a TiZ target as you have to go again anyway.

I recently read sparecycle’s blog with some data, including VO2 about this type of hard-start intervals. He’s saying to aim for 90% MHR.

Not following what you’re saying here. 90% of VO2max, while a legit metric, would be hard to implement as a practical training protocol. Most people don’t really have a way to keep track of 02 consumption real-time during a workout…and if they do it just plain sucks to work out that way. Even if you’re using that tubeless VO2max mask.

Also, ‘100% VO2 max is > MHR?’…if MHR=max heart rate I don’t think anything can be ‘more’ than a maximum unless that really wasn’t a maximum. But in any event you don’t have to be at max heart rate to be at maximum oxygen consumption on the bike.

Maybe it would be a good idea to find somebody who can measure your oxygen consumption & just go fiddle around with some intervals/ramps so you can get a feel for what VO2max feels like. That helped me out a lot. For me, I found out that VO2max was a lot HARDER than what I had been led to believe. Those Billat intervals are not VO2max…three minute VO2max intervals can be but for the most part, those aren’t either for the first few intervals.

Never paid super close attention to heart rate except to say oxygen consumption definitely reaches a plateau BEFORE heart rate approached what would have been the highest I’ve ever seen on a bike. Like…maybe 10 or 12 beats lower than what would have been ‘max’?

Indeed but if you look at some of these %VO2Max calculators they all indicate 98% VO2Max occurs at 100% HR :man_shrugging:t2: Daft to me.

This was my conclusion after I flatlined in progress over the last 2 years with the TR Sustained Power Build. When I looked at my HR just as a response to the interval it got lower across the years and it was eventually lower than the 90% Max HR for the last interval so practically useless. Hence my experiment before I head into the off season to play around with VO2 max sessions. To see if I can get them to work properly.

Well, I don’t know…that’s why I ask. Is this everybody’s experience? I know for me oxygen consumption maxes out at a heart rate that is well less than what I would consider a maximum. But maybe that’s not everybody else’s experience? Let’s hear from people that have done it…what did you see?

I would need more information to really comment, but I can say for a fact that what you report would be quite unusual.

In fact, it implies a significant degree of left ventricular dysfunction, e.g., due to ischemia, such SV falls markedly as you approach VO2max. This would necessitate a compensatory rise in HR to maintain/further elevate Q. (A-vO2diff widens during exercise, but is already close to maximal at submaximal intensities.)


I was just reading through the paper that I talked about in my ‘Anatomy of a 15 minute Vo2max interval’ post’ Looks like the subjects in that paper have the same problem I do! I wonder why such a uniform sub-set of athletes are experiencing a plateau in oxygen consumption previous to reaching max HR…especially if it’s so unusual? Maybe it’s the type of workout we’re doing…

This is the bit I am struggling with too I thought that your VO2 max arrived before you hit MHR!

Maybe for some but not for me. I got to a point where oxygen consumption no longer increased at a HR that was about 12bpm less than my max HR. So maybe I’m unusual in this respect.

Also, maybe more argument just to go do some VO2 work with a mask on & see how it feels. Not to spoil it but it feels like crap & it’s made even more uncomfortable by having a tube jammed in your mouth and a clothes pin on your nose. :smiley:

Cycling MHR is probably a bit lower than absolute MHR. But then so should be oxygen use…

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Thanks. Yup, I’ve said that. And honestly now I would back up a step and just say “go 9/10 effort”, whatever that means to you, however you want to quantify it.

From what I’m reading and working on, I would suggest that we don’t need to max out intensity (VO2max, HRmax, Wmax, 10/10 RPE, whatever) in order to see improved performances a few weeks down the line. Consistent training in the target intensity zone (again, however you want to define that… just be above threshold) should be the main focus. Details beyond that are definitely important, but impossible to generalize. Applies to well-trained and recreational athletes, but your results will vary.

I’m very happy to debate (in good faith) the question of how close to 100% intensity is necessary! I think the answer is slightly lower intensity (as long as still within severe domain) in favour of slightly longer interval duration and greater volume/frequency/consistency. But I don’t think it’s a settled answer!

Can we clarify, if we want to talk about VO2peak in any given workout (which we should be talking about instead of VO2max). Then we can probably say we don’t necessarily need to reach our HRmax to be at our highest achievable VO2peak on the day?

As in, practical training advice can account for not hitting strict 100% HRmax or VO2max in a “VO2max workout” (however we want to define that), for it to be appropriate and effective?

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