Zone 2 training with Iñigo San Millán, part 2

Curious how often this is constrained by a event date or start of the race season? Ive always just planned backwards from the start of my race season so whether base adaptations have been maximized or not its time to move on, or do you shorten the build if necessary? Say you get like 90% of the desired base in terms of decoupling would you try to eek out the rest or call it good enough and that the bigger gains would be made in a full build?

I think it just depends on the athlete and the goal event. Good enough is good enough. It’s not like you go into a build and stop doing steady endurance rides or even progressing duration of those rides necessarily. You can still build endurance in a TTE block.

Of my 10 coaches athletes at the moment, maybe one of them is going to be calendar limited in that way. Most of them I’m building long term aerobic fitness, so while there will be blocks where it’s not the focus, pushing aerobic adaptations will be priority for probably 42 out of a notional 50 week training year, for example. That is just the nature of the level of athlete I’m working with, for the most part. In one case, it’s the nature of working with someone whose focus is marathon MTB.

It shouldn’t in that context. But again, I’m coaching mostly remote athletes, so when I see 20% decoupling, I’m pulling the string for subjective feedback, fueling, environmental factors and then making decisions based on that data in context.

When you’re self coached, you have all that subjective information right at hand so if you’re able to be objective with your own training, you can make good decisions.

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Essentially this just boils down to subjective vs. objective. I’m coached by Empirical now myself, so I’m pretty well aware of how they program their endurance riding. The answer here is a little of both, and I think you seem to be pigeon holing me into saying “I only progress duration when decoupling is less than 5%”, and I’ve made pains to say that is not the case. It is a metric I look at for the duration of those rides to see if we’re challenging the rider or not, taking a whole lot of other information in for context.

As mentioned, more often than not, the limitation we run into is “life” or just sheer will to get out on the bike for certain durations. Not fitness. Not decoupling. I doubt that there are many coaches out there, probably including Empirical’s, that would take some of my athletes and tell them “Go ride for 6 hours” when the longest ride they can regularly do is 3 hours whether limited by time or limited by their endurance. That’s just bad coaching.

So all that to say, decoupling is one metric I look at to determine if what we’re doing is effective, and it is one metric I look at to determine if we are challenging an athlete’s endurance or if we need to push longer (or maybe harder).

If I wasn’t clear on that before, hopefully I am clear on that now.

Yes, and not pigeonholing, just responding to your original question on my backwards comment and not all the words between the backwards comment and here. :+1: I’m coached as you know, and I can’t speak for my coach but where I sit it decoupling is largely uninteresting in my own data - decoupling nearly always low up to about 2.5 hours, even on 1x90-min tempo and 1x30+ min threshold efforts.

However above 3 hours it hard to control conditions plus all the other possible variables at play, and therefore over 3 hours there is large variance on decoupling on my rides.

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Sorry for the multiples here, but this is less a response to any one person. Here’s a sample of a simple report and a graph I made in WKO5 for tracking long ride performance. This is a master’s athlete, and I kept his long rides reined in a little bit early in his base phase during a SST TTE progression, and then as his endurance came up, gave him a range of times he could ride, and he always opted for the longer duration (which is great!).

As I look at this, I see that his endurance improved significantly riding in that 4-5 hour range, and since he’s good at pacing and keeping things in control, I felt pretty confident letting him go ride as long as he wanted to (the prescription was 4-6 hours). He threw some 6+ hour rides in there, and that really stressed him as the reduced EF at those durations shows even with relatively low decoupling, but then EF started to come up before we moved on (now to his VO2max block).

(That decoupling outlier day was one of the hottest days I’ve ever been on a bike in October. He rode long that day as well).


It might be in this thread that I read about it but can’t find it now, there was some discussion of Z2 efficiency. ie riding in Z2 with a lower heart rate… Wouldn’t that be a sign that your FTP has simply increased, meaning that power is a lower IF for you now? Just trying to wrap my head around what is happening with Z2 efficiency.

It could, but not necessarily.

This thinking conflates the concepts of endurance and threshold. Yes, if FTP goes up you will be able to ride at a higher absolute power when you’re at (for example) 65% FTP. This is a very common occurrence off the couch/injury or new to the sport (many TR users). Someone riding endurance with a 400W FTP is naturally not working as hard at 210W as I am. It’s analogous to an 11th grader being better at math than a 4th grader. How does a 4th grader get better at math? Easy, he just gets himself to the 11th grade. How do you make endurance easier? Simple: just get a 400W FTP.

But after some time as a cyclist your FTP more or less levels off. Then what? To ask another way: how do amateurs with 410W FTP get beat by world tour pros with 375W threshold? (same weight). Because the WT pro has significantly better endurance.

Moreover, you can experience significant improvements in endurance while threshold remains the same or even goes down (one of the main themes of this thread as well as any “ride slow to ride fast” discussion). Often you can see this with increase in TTE, better trends w/r/t EF and Pw:Hr, and simply how you feel after extending long rides.

Endurance + threshold. Loosely coupled, but not the same.


I read somewhere that you are better to use heart rate for endurance zone.

Best way to think is for the same heart rate your output watts increases over time… which should mean EF and IF trend up (assuming same FTP setting is used) as your endurance improves.

Efficiency Factor is normalized watts (output) divided by average heart rate (input).
IF is Average Power divided by FTP

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It is all about where VT1 is as % of FTP.
You can raise Z2 power by increasing FTP or by increasing the %. The latter is called endurance training and is one of the major benefits of these long Z2 rides.

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This is true. FTP is not the best measuring stick for a 4-5 hour ride or race. Here is an article that highlights what you were saying:

From the article:
“It gives information about the current performance level for constant intervals and efforts, but it only gives me a number, and nothing more. It doesn’t tell me what happens if the athlete continues for more time at that effort.”

Many world-class male TT specialists have FTPs well in excess of 400 watts; Bradley Wiggins’s Hour Record power was estimated as 440 watts. However, in long-distance road races, it’s not what you can do after 20 minutes, but what you can do after five hours that counts.

“FTP doesn’t capture athletes’ durability or ability to repeat high-intensity bouts during races,” says Seiler. “It tells us something over a short period of time, but over a long period of time, the FTP power deteriorates. What is going on in their body after three or five hours? I want to know how durable your body is at low power, and its ability to repeat high-intensity efforts over time.”

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When I read that it came with the disclaimer it was because of coming from a real off-season, you could expect quick fitness gains when coming back to (base) endurance training. And that it wasn’t practical to test every week, and that HR zones are pretty stable and don’t change.

That has proven to be true in my own training, and thats when I use HR zones. Sometimes I’ll use HR caps, for example the first handful or two of times when temperatures jump from warm to very hot.

Otherwise its always training by power or full-gas, and always recording power along with HR.

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a.k.a: endurance.

(I agree with KM on this one. Not sure why the need to rebrand something we already have a very clear term for)

Because when you distill all the training insights it pretty simple concept. Basically you need 3 workouts in patterns. When you are a coach - there is periodisation, preparation and all that fluff. When you are a storyteller / scientist like Seiler - you have to find a way to tell the same story, known for years, in a different way. And he tells his story very well apparently. There is not much “meat” but a lot of charisma.


no it cant. there are not shortcuts. study has wrong conclusions.

if so it is vt1 as a % of vo2max. and how high is blood lactate at this point.

I would’t call double days a short cut.

No doubt, the long ride is the most important piece of training and a staple that should be in every endurance riders training plan. But the article is saying that in terms of volume, instead of a 2 hour ride, if you only have time for 2 x 1 hour you can get pretty close. At the amateur level I have observed this to be true.


oh absolutley, i agree, it can be even more effictive to do double day sessions.

i was referring to something else in the study. there are not really shortcuts in terms of kJ - the work has to be done, in the right way.

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