This is what I don’t understand. Isn’t being more efficient allow you to have more when you really have to push glycolytic efforts?.
Or this is negated because now anybody can have 100g of sugar per hour?
What does knowing your Fatmax change about how you train?
Sure, but what does the metric itself tell you to do with your training or racing?
It’s difficult to parse through the long off topic debate in here, but I just wanted to interject and say that Fatmax is certainly actionable and in fact is a very important consideration for the guys doing what is essentially pro level volume.
In short the TSS of a ride will be much lower for the same level of effective training of z2 focused systems by staying on the correct side of fatmax.
The power v fatmax curve is roughly a parabola with the same effective fat oxidation rate on both sides of the apex, however as I said above the lower power side of that apex will result in less TSS per ride which carried over to an increased ability to train during that block (possibly in higher zones as part of key workouts)
But knowing exactly where that is for an amateur is not super relevant as they are likely not pushing it in terms of the hours on the bike or maxing out on TSS for a block. They can afford to be 10w below fatmax just to be safe.
Thanks for your input. To me it still sounds very similar to: ride endurance. And if big volume: then not to hard.
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If it was low, I would try to increase hours at the cost of less intensity.
I came across the Empircial / Coggan interview where they discuss Vlamax:
Vlamax starts at 50:10
fwiw, Fatmax is incredibly applicable to ultras and I think if ultra racers could get this measurement periodically, it would be helpful feedback for training. I wish I knew this number and could track it without lab testing.
I only have anecdata from misadventures involving GI distress. **** happens over long distances. Knowing the extent to which fat metabolism can take up slack has been make or break for more than one race of mine. You get into situations where continuing at a lower pace might be a better option than waiting several hours for a store to open up.
Interesting
I don’t know that that’s true.
We use TSS as a metric to predict:
- Training stimulus from a workout, and
- to predict fatigue from a workout.
You seem to be saying that the location of fatmax in relation to work done is the major factor for the training stimulus and accumulated fatigue of a workout.
As far as I’m aware there’s no evidence at all behind that assertion.
In particular, we don’t understand the factors contributing to fatigue with certainty to begin with, so I don’t think you can make any claims that the location of fatmax predominantly influences this.
And then I’ve never seen anything that suggests that the work done in relation to fatmax is the predominant driver of training adaptations.
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What he’s saying is that the Fatmax curve is an inverted parabola, and it’s a fairly “fat” one at that, meaning the apex is relatively shallow vs. the rest of the curve. So if you are trying to train near Fatmax, say, 95% of Fatmax, there are two points where that can be accomplished: one is below Fatmax “power” and the other above it. So for example if Fatmax occurs at 72% of FTP, you can train at 67% or 77% of FTP and be working at the same % of Fatmax. Necessarily, the one where you’re riding at lower power is going to give you a lower TSS, and allow you to train for longer operating at that % of Fatmax.
Now, whether or not that actually matters to most cyclists is certainly up for debate, and whether or not there’s real value in knowing your Fatmax (either by actually using a metabolic cart or by estimating it via INSCYD test) for most athletes is as well.
My argument is that most cyclists do not achieve better performance by creating some focus on burning more fat. There is a subset of cyclists that do - ultra/audax/Grand tour riders, etc. If you’re one of those guys, have at it if you must (but you don’t need to.)
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@kurt.braeckel So it sounds like riders could just train in endurance and tempo zones if they wanted to target fatmax without having to pay for any testing. 
Coggan weighs in on fatmax as well in one of those Empirical interviews. I’m not going to find the reference for people but one can guess what he would say.
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Agreed. And even for that subset, the usefulness is attenuated by the fact that you have to go to a lab to get the number. Do you know if there is any analysis in wko5 that hits the same or adjacent concepts?
A big unsolved question in my sport is how many long endurance rides you need to upkeep the endurance adaptations. Anecdotally, it seems once you get past a certain level, the gains stick around without much work. It would be nice if there was some sort of proxy that could be measured, other than “go bike a couple hundred miles and see how you feel.”
Bingo. I think most people that are chasing these Fatmax based training numbers are essentially searching for the lightest carbon bottle cage mounting bolts they can find.
I don’t. I haven’t spent much time worrying about it for reasons described above, and I’m fairly certain Tim hasn’t worried about modeling it for those same reasons.
Again, just my opinions here.
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Really? I will admit I am not super active on Reddit and don’t really know who there is or is not a EC coach but I have not seen them advertise their coaching business there beyond the occasional “talk to a good coach” advice. 
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r/Velo can be a tough sub. Holding a grudge over a nerdy interjection?
I really don’t see the cartel thing on r/Velo. I’ve never seen them pimp their coaching service. I’ve only seen them provide free help.
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My argument is that most cyclists do not achieve better performance by creating some focus on burning more fat. There is a subset of cyclists that do - ultra/audax/Grand tour riders, etc. If you’re one of those guys, have at it if you must (but you don’t need to.)
All of the conventional anecdotal and technical evidence says that the metabolic flexibility model proposed roughly by ISM in his paper is the dominant model for creating tadej pogacar, the ideal rider. The fat burning is part of the aerobic metabolism which is running super hot due to the constant stimulus, the rider can then also consume mass calories dumping directly into their glycolytic systems without seeing a marked decrease in aerobic function. The result is a completely other level of rider. Now whether you have to “focus” on more fat burning to achieve this in training or as part of planning training is somewhat trivial, you can focus on a picture of puck moonen on the wall if you like as long as you follow your workouts.
And then again in the post ride meal planning the fat has to be accounted for pasta is good food but in base season it should be especially greasy if you know what I’m getting at. The athletes have practically burning many many kcalories of fat.
The ultra guys, yes it’s their bread and butter, on the long distance they run mainly on this engine alone for long times, but it was in fact a look into olympic pursuit teams that originally helped me understand that these guys are doing 4 minute pursuits in the race but training for 4 years on 900 hours per year massive volume of aerobic base. The ability to maintain this aerobic metabolism during training leading into key sessions allows the athlete to reach deeper into their potential and apply greater stimulus to their muscles which they can recover from and adapt suddenly bringing all this aerobic gobbldygook into the real world aka out of the blood and the muscles, crossing this intangible grey zone that has precipitated the long off topic discussion of this thread re: fatmax as a black box zone with no super obvious reason to look inside.
Then when you are talking about what kind of workout to do to leverage aerobic training into the most pure carving out of potential you really need more specific workouts then anything the usual suspects suggest. In all fairness TR has some of the best specificity workouts of course you will need to go nuts and not follow the pacing limitations that the program suggests , but certainly if your coach prescribes you a long sweetspot workout after a high volume block you should fire them.
Some example polarized workouts that worked for me are as follows
Some trainer road stuff
but you have to get after it, it’s not about completion of the workout it’s about making all that base REAL by smashing your legs.
Taking full advantage of the mixed sprints sessions
custom very very difficult workouts (the middle block is a 10 minutes effort of 6.6w/kg for 2 minutes followed by 6 minutes at sweetspot followed by 2 minutes at 6.6w/kg.
You could do a sweetspot workout of like 2.5 hours in duration instead but the honest reason that this kind of thing is suggested so much is because it;'s easy to schedule and isn’t in any way custom. it’s a straight up F-off workout from a lazy coach.
Virtually all cyclists should have enough fat stored on their body to fuel these efforts, and excess calories are readily converted into fatty acids. You don’t need to focus on dietary fat. Furthermore, iirc the studies on high-fat diets show that the fat adaptation gains are quickly lost once switching back to a regular diet.
Ultra racers tend to be highly fat-adapted, but not due to any dietary modifications. There’s an emphasis on protein intake during multi-day events, which tend to be pretty catabolic. To my best knowledge, the only area where fat intake is actively sought out is the niche-within-a-niche multi-day winter ultras. And that’s more to keep up with all the extra calories burned trying to stay warm. It’s hard to eat something like 6,500-10,000 calories a day without fat. Fatty foods are compact calories, also tend to not freeze as hard.
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“virtually all cyclists” is not the “ideal metabolic flexibility model cyclist”. Normal people can eat whatever they like.