yeah, after last season’s struggles, I’m not totally bailing on the short hard intervals, but I am just waiting until I started my build, and doing general build instead of short power. There’s not a huge amount of difference between them, but now with no racing, it’s really just an experiment to see how my body responds.
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This is correct. The value quickly reaches a plateau with training (about 6-10 weeks depending on how hard you push) and hits a wall. Over the long term it can move quite a bit but not by hammering anaerobic intervals.
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What I think you’re missing here is that not all muscle mass experiences the same stress in training. If you do a steady 30’ FTP interval, this is different than doing 30’ of 15/15s or something like that.
But since we’re on this again, this is another issue with looking at FTP through the lens of vlamax. Not all muscle fibers are equally trained, so when you make big watts and create tons of lactate, you’re using more motor units than just the ones you normally just do FTP with.
The size principle!
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Edit: Sorry to hijack the thread, I meant to post in the VLaMax podcast thread 
I thought to contribute to this discussion just a little bit because of all the assumptions floating around here.
It is an issue when a lack of knowledge is filled with unchecked assumptions and drawing conclusions which are then sold as facts.
So to start with:
I am not a salesperson but studied sport science / exercise physiology (graduated with honors) and then molecular human biology.
Before starting INSCYD I coached recreational and especially professional cyclist and triathletes, some of them were quite successful.
Re what is all so wrong about INSCYD:
- no constants fell from the sky, and none is derived from statistical data from myself or of anyone collected during the past years. All constants - as well as anything else in INSCYD- is derived from peer reviewed papers of different authors, years, sources etc.
- However the calculation performed in INSCYD have been compared to empirical data derived in vivo and in vitro. This includes lab tests, field tests and > 100 muscle biopsies.
- The mystic 1986 paper: I actually had to look it up to understand which one was meant here. Frankly only looking closely at the graphs would allow to understand that this is not the basis of INSCYD. In fact, I didn’t even use this paper in my 2003 thesis but more advanced literature which was already out then.
- This said I have to disappoint people who think or assume we would have just taking one publication and hacked some equations into code. In fact, as also stated on our website, the algorithms are based on a variety of papers, actually there a lot (see bulletpoint 1 about constants - same thing).
- VLamax is or is not glycolytic power?! Short answer it is! Anyone who says different doesn’t understand what VLamax is at the first place. Maybe this is because of the method from my 2003 thesis were we used 15s sprint test using pre and post lactate to determine VLamax as a proxy ?! But for whatever reason, no one should make a mistake here: VLamax = glycolytic power, period!
- The mechanism that reduces fat oxidation at higher intensitites is wrong: it is invalid to make a statement that a mechanism is wrong when the mechanism which is referred to is unknown to the person who makes this statement in the first place.
- Substrate use at AT isn’t 100% Carbohydrates. This is actually a classic one, a topic we speak about a lot (with people who speak to us instead of criticising from a distance). This means users of INSCYD get the explanation behind this, which is: INSCYD displays 100% carbohydrate combustion at intensity > MLSS. When one compares this to the published data (for example Jeukendrup) you will see that there is a measureable small amount of fatty acid still being utilised. The disconnect here is: the graph in which INSCYD displays carbohydrate being 100% above MLSS has two attributes: 1) it is related only to the working tissue which contributes to power production, 2) it is in steady state conditions, which means mathematically time is infinite. So in comparison to, for example lab data: the measured substrate utilisation is almost always whole body. And non locomotion positive tissue may well show a descent amount of fat oxidation, hence contributing to the overall fat/carb rates and pulling the % of fat rate up. Second in no lab scenario time if infinite. Fatty acid utilisation is reduced at intensities > MLSS with increasing duration. When you put duration infinite, fat oxidation ends - pretty simple.
- In case someone is interested in a case study (n=1 but nicely done) comparing fuel utilisation of a PhD in exercise physiology who was very critical about what we calculate and therefore challenged INSCYD instead of doom it, look here: https://www.inscyd.com/blog/ppd-validation
- Carbohydrate oxidation at zero power: there is a resting lactate value and a resting metabolic rate and there is a needed minimum rate of glycolysis, hence there is a utilisation of glucose aka carbohydrates.
- Vlamax can be measured by power output only. Just because one doesn’t understand or know how something is done doesn’t necessarily mean it is impossible.
- The average error in calculating MLLS power or AT power using INSCYD in cycling is 2.0 - 2.5% (males and females). The highest deviation seen was approx 6%.
- The fact that INSCYD uses lactate concentration quite a bit sometimes seems people to assume that INSCYD is based on some kind of correlation between blood lactate concentrations and other physiological metrics such as fat combustion or VO2max or what so ever. This isn’t the case either, as mentioned above, INSCYD isn’t based on statistical correlation. And it doesn’t use the lactate concentration only or primarily but the mechanisms which compose a certain lactate concentration.
Lastly I would like to mention to everybody who brings a healthy level of scepticism:
mostly every scientist, coach, exercise physiologist etc. has this scepticism, and this is how it should be.
Feel free to get in touch or challenge us - like in the link above. This is the best and only way for yourself to find out more and get questions answered.
Hope this helped clarify a few things.
cheers
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Since you’re here, why do your model outputs always show 100% carbohydrate use at FTP and carbohydrate oxidation begins directly from rest?
I’ll leave vlamax alone, you and Andy had a good discussion about it on twitter and I’m with Andy on that one.
I’ve got no pony in this show, just observing that TR has been attracting some big hitters these days. 
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I don’t believe good discussion are possible on a network like twitter.
Re your carbohydrate question you might want to check my previous post as this is answered there.
I put this up there because this is exactly the right questions and right discussions to have.
Instead of dismissing something that can’t be understood at the first glance, asking the question “why is this…” because the people who created it will have done their diligent work and it might actually be correct.
So please let me know if the explanation above is sufficient to answer that question.
This said, there are analysis and visualizations in INSCYD where carbohydrate isn’t 100% at FTP or above, but those are related to other physiological / load scenarios than the ones you are referring to.
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It’s very difficult for me to believe that you don’t know the Mader & Heck paper since that’s the original paper that discusses the origin of FTP as a combination of vo2max and vlamax.
The mechanism is not unknown, it’s just that you don’t know. The length of your answer for carbohydrate combustion at MLSS is funny and wrong. It’s pretty clear you’re missing some pieces of the metabolic puzzle, and you are over-interpreting the role of lactate like so many others before you.
Oh I didn’t say I don’t know the paper, I said I wasn’t aware which one particular was referred to here.
There are several publications tackling the same topic, older and newer ones. And because INSCYD isn’t based on only one or a few papers, it is pretty straight forward that this was just another wrong assumption.
Re your other comments:
We have been there before right ?! You make bold statements what is all so wrong but fail to justify any statement.
I leave it this way: I have no clue about metabolism (thank god there are other people at INSCYD who maybe do), all statements are wrong, just smoke and mirrors.
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In your opinion, what limits VO2max? Performance?
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What a shame that this discussion was not more productive. I enjoy EmpiricalCycling cast and would have loved to see a good argument being brought up here. Instead, criticism is too indirect (and also formulated super unproductively) and Sebastian Weber dances around it without trying to / having to explain something.
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Unfortunately typical, as he has good things to add, but always seems to devolve into this.
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Agree, I have really liked both the Empirical Cycling podcast content and the Sebastian Weber interviews on That Triathlon Show. Feel my training and understanding - hence enjoyment - of training has improved through both. And those podcasts are free, plus they are contributing here, we are so spoilt.
But I feel there’s more to gain from observing common ground between the coaches than from an argument that I simply don’t have the knowledge to judge.
Maybe, for example, it seems to me both KM and SW do seem to promote the idea that you can train in a sophisticated and productive way without needing blood lactate measurements from a lab. (With WKO analysis and the newer INSCYD remote testing respectively?) Unlike other well-known-on-the-internet coaches e.g. maybe Alan Couzens? (Though I appreciate AC maybe has a slightly different target audience in long course triathlon? Plus I think his content is great as well. And again free. I’m just not in the market for testing.)
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Jumbo-Visma seems to be doing okay this season despite ties to inscyd. As a viewer of the spectacle, i am thankful they dont use anything half decent. 
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Everything I’ve read/heard about Inscyd comes across without any criticism. Actually I’m going to try Inscyd myself.
Still, I wonder - can some the parameters be modeled in WKO5 or Xert?
Isn’t Inscyd just an algorithm backed by athlete data? I mean they test a bunch of people in a lab so they know their exact numbers and they know how they perform on various on-bike tests. Now, they test athletes on the bike and tell them what their lab values should probably be. It’s not exact but they think it should be really close. Right?
I haven’t used Xert in a few years, but do actively use WKO5. Pretty sure the only unique items in the INSCYD report are VLamax and power at FATmax. I was somewhat surprised my VLamax was so low, but from a practical point-of-view it hasn’t influenced my training. Having done an INSCYD test, I’d be happy just using WKO5.
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My thoughts exactly.
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It’s quite obviously because they’re not using disc brakes.
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