is objective, but the arbitrary point would be that being at fatmax isnt special for aerobic development.
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Yes. That’s my point, to my knowledge there are 2 non subjective levels:
- Fatmax
- MLSS
Seems a lot better than %. Also, how does a coach prescribe tempo or SST by RPE?
yea i getchu but the debate isnt whether fatmax exists (it does) its whether training at fatmax is significant
oh and #3 is vo2max
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AFAICT, it’s a broad range of watts on a graph. Lots of things can be plotted on a graph. It doesn’t mean that it’s a particularly meaningful training intensity.
I’m not saying that it’s a poor training intensity to target but the way ISM does it is confusing. If one is relatively untrained, fatmax will be low. World Tour riders probably have a very high fatmax that their fatmax intervals are close to threshold (sweetspot).
Fatmax is also highly influenced by fuel. Fuel with protein and fat and your fatmax will be higher. Fuel with sugars and your fatmax will be much lower. The body is going to gravitate towards the most available fuel.
ISM has made a lot of this super confusing to the public that doesn’t have access to metabolic testing. He’s offered 2 mmol of lactate, talk test, and fatmax as his “zone 2”. And why zone 2, renaming what has traditionally been zone 3? Just confusing from all sides. Plus ISM has done the health and wellness circuit promoting his “zone 2”. He’s done few cycling training podcasts nor has given much in the way to specifics so people are surprised when he says he also prescribes hard intervals for his athletes. Of course, they are going to do intervals.
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Ok. Got it. I don’t follow ISM or anybody’s particular training approach, however I would find it more credible if a coach said: “ride a bunch at or below Fatmax and 2 days a week intervals at MLSS and Vo2Max” than the typical recipe of % of FTP. Maybe just me.
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I thought you could easily manipulate Fatmax test results by changing diet or timing of carb consumption. If that is true, I really don’t understand this idea its some type of physiological marker. And even if Fatmax measurement is highly repeatable and accurate, I thought the notion that you “train fat oxidation” has been debunked.
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reference?
The point is, if it’s a reliable measure. It’s an actual market of something, instead of a dubious % of another erratic estimate.
It has been known for approximately 150 y that both acute food intake and habitual diet influence substrate oxidation during exercise. In fact, in the early days these were the primary tools used to alter the mix of substrates oxidized during exercise.
References:
(Cf. Chapter 17)
(Cf. Chapter 1)
Coggan AR, Mendenhall LA. Effect of diet on substrate metabolism during exercise. In: Lamb DR, Gisolfi CV, eds. Perspectives in Exercise Science and Sports Medicine, Vol. 5: Energy Metabolism in Exercise and Sport. Dubuque, IA: Brown and Benchmark, 1992: 435-464.
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Easily, but more importantly, so-called “Fatmax” is just another indicator of muscular metabolic fitness, and is highly correlated with any and all definitions of lactate threshold.
IOW, it’s not an independent measurement, but just another way of measuring the same thing.
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Yeah. That actually tracks. 
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You presuppose that “Fatmax”, “LT1”, etc., can vary independently of any other measure of maximal metabolic steady state. Yes, I know that that is the trope here, but I say…
…show me the evidence.
FWIW, here’s some of mine (Fig. 2):
(Hopefully folks here are smart enough to “get it”, and understand the implications of that figure/those data.)
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I couldn’t resist this one either 
Here are a few refs that immediately come to mind
Here’s a very good review of all the operational decisions (methodological differences) that go into estimating a “fatmax” value.
Here’s a great recent modelling paper showing the strength of how different factors (dietary intake, starting CHO levels, exercise intensity, fitness, age, …) all influence respiratory exchange ratio, i.e. substrate oxidation rates.
Don’t forget how changing cadence will influence subsrate Ox!
And probably an important one to read. Gives us permission to relax about training at FatMax ± 1 W being a particularly magic number.
Not if, but by how much. Everything has uncertainty. One attempt to quantify that uncertainty:
This week, are you the red line or the blue line between any two training sessions? How about next week? 
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Thank you for helping me beat the dead horse.
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There’s gonna be someone new encountering an idea for the first time every day of our lives 
Hopefully tomorrow it’s our turn
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Would the individuals RPE be similar at any point on “their” line ?
He asked, we answered. 
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From my experience, I tested Vo2max for 4 times already. Also tested lactate many times just to understand how my body work)
First, I think you must have a good fat oxidation. (From my experience, trianing at or below FATMAX really help - i can notice that I drink less water and breathing rate in the lab is lower for the same effort)
Then training at zone 2 (control average power) 3-4/hours, fuel properly and have some days for doing intervals also. (10-15 mins zone 4 or Vo2max intervals)
After 2-3 months I can feel that I will ride at around average power 60-65% FTP naturally. I mean if I don’t intend to ride hard it will always be around that power. And I can go longer with less fatigue. So I can train more. (He said that it improve aerobic capacity, not power)
Eventually when you can burn fat better and training longer so you can lose weight easier and have more stamina to do hard intervals, to make an improvement.
(I learned a lot from this post so I just want to share my experience. 
)
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Assuming that fat is virtually unlimited and glucose is limited. Doesn’t it follow that it’s an advantage to “train” the body to use more fat via diet, thus reducing the need for fueling carbs during prolonged exercise?
No, I wasn’t. My only now misconception was that Fatmax was a more robust level to anchor training.
I really appreciate the references and the article, I have a couple of questions:
-
In this forum, you have repeatedly said your levels are descriptive and not prescriptive, yet in the iLevels article you linked it says the opposite, what gives?
-
You once corrected me regarding your expertise, which you added exercise training on top of exercise physiology. Taking that at face value, and simplifying all the assumptions about a particular individual……it must follow that you have a recipe for training with the sole goal of increasing one’s FTP….
Would you care describing it?. How is it different from what most coaches prescribe, Tim Cuisick included?
Thanks
Thanks a lot for the references. I have a follow up question:
It seems that diet, timing of macronutrients and cadence are the main sources of variability for the substrate utilization tests. Yet, these are knowable and controlable, specially in crazy regimented people like us cyclists and more so professional cyclists.
Cadence: Self-selected. Fixed
Diet Composition: Easily controlable towards a desired outcome.
Timing of CHO: Easy to follow a prescription
Assuming we now have control of these variables. Can we recover the realizability and usefulness of the test? Isn’t this what professional teams are doing?
Thanks
I think the point is that there is no specific intensity that “trains the body to use fat”. But rather that all training does this and that in fact training harder does this more than training easier (if time is equal).
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