Iñigo San Millán training model

I think it’s time to start a dedicated thread on this. This is an interesting topic, the Pro/Elite is not the proper place for this. Personally, I find this an interesting model.

Perhaps someone else wants to copy in some relevant infos from the Pro/Elite thread.


On this again:

From another study on fairly well trained roadies and triathletes:

He definitely does not mean zone 2 with the given range

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Pickup up from the other thread…

Not sure where you are getting that, but I know you are more interested in lactate testing (and I don’t pay much mental attention to lactate).

Listening to Dirk Friel’s interview I heard San Millan say:

  • Pogacar’s lactate clearance is world class
  • Pog’s curve is very flat and starts at 0.6
  • when Pog is at 1.2, a typical world class rider is at 3.0
  • when Pog is at 3.0, a typical world class rider is at 6.0

From listening to several San Millan interviews, it seems to me he doesn’t pin it down to specific lactate values. Its depends on your curve. The zone 2 in the 2014 article appears to be above Aerobic Threshold because it involves energy from both fat and carbs (so it doesn’t appear to be Seiler’s zone 1 which is below aerobic threshold).

In the context of Pogacar he states:

  • several days a week train in zone 2
  • several days a week either train the glycolytic capacity or build glycolytic training into a zone 2 session

which brings to mind another San Millan article on the TP blog in which he states:

“Therefore to improve lactate clearance capacity, and although totally counterintuitive, it is key to train those slow twitch muscle fibers to stimulate mitochondrial growth and function as well as increase MCT-1 and mLDH.”


“Training at lactate threshold is essential to improve glycolytic fibers and their machinery (our “Turbo”) and to upregulate the number and function of glycolytic enzymes as well as to increase the number of MCT-4 transporters necessary to transport lactate away from fast twitch fibers to then be cleared by slow twitch fibers.”

Source: https://www.trainingpeaks.com/blog/what-is-lactate-and-lactate-threshold/

This message is also referenced in the Zone 2 training article mentioned above:

“Therefore, lactate is mainly produced in fast twitch muscle fibers which then, through a specific transporter called MCT-4, export lactate away from these fibers. However, lactate needs to be cleared or else it will accumulate. This is when Type I muscle fibers play the key role of lactate clearance. Type I muscle fibers contain a transporter called MCT-1 which are in charge of taking up lactate and transporting it to the mitochondria where it is reused as energy. Zone 2 training increases mitochondrial density as well as MCT-1 transporters.”

As already pointed out in the other thread, the following structure (as given in the TP article) appears from his Strava:

An endurance athlete should never stop training in zone 2. The ideal training plan should include 3-4 days a week of zone 2 training in the first 2-3 months of pre-season training, followed by 2-3 days a week as the season gets closer and 2 days of maintenance once the season is in full blown.

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On this again:

That is a direct quote from San Millan, not me:

not following the point you are making. Are you saying San Millan is wrong?

San Millan’s zone 2 from a TrainingPeaks blog post:

Therefore zone2 is NOT below Aerobic Threshold (Coggan’s zone 1, or Seiler’s zone 1), where the energy substrate is predominantly fat.

Those zones sure look a lot like Coggan levels, where tempo / level 3 efforts involve enough force that Type IIa fibers become more actively involved with energy production. And where threshold / level 4 efforts require significant energy production from carbs.


As San Millan stated in another TP blog post, Fitzgerald’s 80/20 rule, Friel’s periodization recommendations, what I see in Carmichael’s plans, what I see in FasCat plans, etc., etc. And San Millan goes further and points out you also need to train glycolytic capacity, as the two go hand in hand in improving lactate clearance.

I’m guessing its fair to say we agree the science is pretty clear and largely in agreement. Now take that science and go look at TrainerRoad’s high-volume sweet spot base plan. What do you see?


San Millan Zone 2 definition 1.3 - 1.8 mmol/L

Peter Attia Podcast and published literature (“metabolic flexibility” paper). Also referenced in Pro/Elite Training thread (images from @sryke and mentioned by @Kipstrong)

Edit (a few days later): Leaving this here but I think it’s expressed incorrectly/poorly. The way he has said it in the podcast has led to some confusion. I do not believe he is saying that it’s a range, as is expressed above. (similar to one saying “ride between this intensity and a higher intensity”). If you come to this thread later keep reading and I think we straighten it out.

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So is that whole blood or plasma lactate concentration? Measured in arterial, arterialized, venous, or capillary (e.g., finger or ear prick) samples? After exercising for how long?

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Yes, there’s a fair amount of overlap btwn Seiler and San Millán. H

Do tell us…I believe my outside unstructured riding fits well the Seiler, San Milan model, with plenty of hard work included (long climbs). In 3-4 weeks I have to start indoor and I’m having second thoughts about TR MV plan. I might have to customize the whole thing myself.

You’re going to have to spell out what I should see, I’m afraid; my exercise physiology isn’t good enough to be sure I’m drawing the right conclusions. But I’d be intrigued to hear your thoughts.

@sryke I don’t think he’s aiming as high as where you have that chart highlighted, above. ie. VT2/RCP at RER = 1.00. In this case, the target I’m pretty sure would be closer to 60% VO2max, based on where Fatmax and LT(2) are indicated. An athlete where VT2/RCP occurs at >80% of VO2max, then the target might be ~75% VO2max.

To the best of my understanding, San-Millán wants his athlete spending lots of time somewhere around Aerobic Threshold/Lactate Threshold 1/Ventilatory Threshold 1/Fatmax, which are all closely related, but not synonymous depending on how they are measured. Seiler defines top-end Zone 1 (3-zone model) at VT2. Coggan defines top-end Zone 2 (5-zone model and ilevels) as a power output that approximates AeT/VT2/LT2/Fatmax.

BLa at this point will be above lactate minimum the minimum observable lactate, ie. that 0.6 mmol number for Pogačar. BLa at LT1 might be anywhere from 1.0-3.0, depending on the athlete and (as always) how it’s being defined.

@tshortt was the quote for 1.3-1.8 mmol BLa the range he wanted his athletes to stay in? Or an inter-individual range at which he typically finds AeT/LT1/VT1/Fatmax to occur? I’ll have to re-listen to his interview with Peter Attia, because I know they talk about this training decisively as ‘Zone 2 training’.

@bbarrera careful when you talk about ‘predominantly fat’. By percentage of total energy production from substrate, maybe. But probably not by absolute volume of substrate combusted. See this figure from San-Millán’s 2018 paper as example. Take note of the units on both axes for CHOox and FATox, respectively.

Could be wrong, but I think the overall intent is still to spend high volume of low-intensity just below AeT/LT1/VT1/Fatmax, and San-Millán uses BLa as a convenient proxy to keep tabs on intensity. I have opinions about BLa, but it still has value. It’s the Dow Jones of exercise physiology, IMO :grin:

An article from a few years back in which a journalist describes a running plan he embarked on under Dr. San Millan’s guidance. One thing that jumped out at me is that the author identifies his Zone 2 heart rate as 160 to 165. Unless he has a very high MHR (i.e. greater than 200) that HR would have him running at 80% of his MHR at least, and likely greater. Not a peer-reviewed scientific article at all, but something that caught my eye nonetheless.

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Yes I have noticed that and was borrowing language from the chart in San Milan’s TP blog on zone 2 training. Sone of these terms are confusing when you look at absolute volume. But I have no exercise physiology background and sometimes parrot what I’m reading. Thanks for the clarification and the graph.

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Lactate minimum refers to the nadir in lactate during an incremental exercise test performed after lactate has been previously elevated. It would be unusual for lactate during exercise to be lower than at (true) rest.

San Millan Zone 2 definition:

Cycling mag:

“Zone 2 training is harder than a recovery ride, but not so hard that you can’t talk the whole time. Depending on your fitness level, it’s between 55 to 75 percent of your VO2 max intensity or about a 5 to 6 on a 1 to 10 scale.“

Running mag:

San Millán was able to give me personalized heart rate “zones.” The six San Millán assigned to me ranged from “recovery” (also known as Zone 1) to “anaerobic” (Zone 6, also frequently referred to as the “red zone”). In Zones 1 and 2, my body would primarily burn fat as fuel and help build my aerobic “engine.”

From the TP article, it’s not clear if it’s power or HR defined zones.

However, taking the “5 to 6” RPE as well as the “not so hard that you can’t talk the whole time” (i.e. talk test), might be safe to assume ‘Zone 2’ is at/below VT1 and/or Coogan Z2.

Got a bunch of ISM podcasts lined up.


Zone 2: The author’s heart rate zone that builds endurance; 160–165 beats per minute. Zone 4: The author’s heart rate zone that is closer to “race pace”; 175–180 beats per minute.

“lactate threshold” Zone 4 intervals.

That’s super high HR for Coggan Z2!


Oh you’re totally right, my bad!

Relevant test methodology here

I’ve been misappropriating that term to refer to the slight drop in BLa observable from rest to low intensity. Which I see in the lab regularly enough. Resting levels maybe 1.0-1.2 mmol, and that can drop to 0.6-0.8, like San-Millán sees in Pogačar.

We also seem to notice it more in better-trained athletes. I’m not 100% sure what it represents - and it could totally be measurement error (fingertip capillary BLa with Edge or Lactate Pro). But I assume it’s related to warm-up effect and increased VO2. Get some extra mitochondria working to burn off pyruvate before La- reaches blood.


Millán the hard-ass:

San Millán’s commonsense approach. “People read these blogs and articles that say, ‘If you only have one hour to exercise, you better do your workout as hard as you can because it’s the same as if you were to exercise longer at a low intensity,’ ” San Millán told me at our last meeting. “No, it’s not. We can’t be so naive to think the best coaches and athletes in the world haven’t thought of that. They’ve tried it—and it doesn’t work. But most weekend warriors are still doing the exact opposite of what the world-class athletes are doing.”

So…there’s that. :thinking:


5-6/10 RPE sounds like Tempo/Coggan Zone 3 to me, but sounds like it’s somewhere around there :man_shrugging:

I bet it’s more individually determined than flat power or HR zones.


That’s what I think too, otherwise why do gas exchange and lactate testing?


Agreed. All measurements are protocol dependent and they approximate the “true” information we want. What we measure and how we measure determines how we define zones and prescribe training. Translating between them gets real messy real quick. Means we should be precise in defining our terms, but not over-precise in defining our zones/threshold/targets, etc.