Latest Seiler talk - 22nd April 2021

Some great info here.

Some new, some old.


This chart continues to be a mainstay…and continues to evolve! :smiley:

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This suggest that my zone 2 can be as wide a a 35bpm range, or as narrow as a 7bpm range :laughing:

LOL, interestingly enough, I altered my long running chart months ago to add and “AR” section for “Active Recovery” to parallel my Coggan version.

I almost labeled it as “Z0” too, but thought that would be odd numbering. Right or wrong, I chose a split for the bottom of Z1 POL around 55% HR Max (50% FTP, 41% VO2 Max). I came to this during the discussions about POL here and especially during the TR episode and recognized that a Recovery section might be more appropriate to add to POL zones as well.

No claims to my chart being right, but I think it’s reasonably close for most considerations.


@stevemz let’s talk about this! :smiley: You’re a guy who has been around so you’ve probably seen your lactate curve…I’ve seen my own a couple times. For me, it’s super easy to pick out LT1 but finding LT2 is some confabulation of belief. If three ppl take a look at the curve they’ll probably come up with three different answers. And none of those answers is going to be a ‘steady state’ condition.

In other words, if I find my power at LT1 on the lactate curve…lactate is ever increasing after that with a steadily increasing slope.

Unlike most people, I really do know what my all day power is. Unlike most people, I really do know what my max hour power is. All day power is very, very close to LT1. LT2 is all over the place compared to max hour power.

So I read a lot of discussion about LT1 and how to find it. For me, it’s super obvious where LT1 is. It’s LT2 that is confusing as all get out. What’s your experience?

BY THE WAY, for those interested, the first question after this presentation was: how do you find LT1? Seiler’s answer at about the 58 minute mark.

Seiler used to say 60-65% of HRmax for LT1. I tried that for my first polarized block and it was too slow. I settled on 70% as a practical alternative. 75-79% is getting into tempo for me.


About the same for me. LT1 is right at 75% max observed cycling HR for me.

You have your terms mixed up.

LT2 is FTP

LT1 is mutters incoherent words under his breath depending on protocol

I was just being annoying and pointing out how Seiler has unspecific guidelines for his zones


I’m just wondering how those ideas jibe with what your lactate curve looks like?

I understand my steady state power in a way that probably less than 1% of cyclists understand their steady state power. I really do know what my all day power is because I’ve gone all out, all day many times. I really do know what my 1 hour power is because I’ve gone all out for an hour many times.

For me, it’s very obvious where my LT1 is when I take my lactate curve. Anybody can look at the data and be w/in a few watts.

For me, it’s NOT OBVIOUS what my LT2 is when looking at my lactate curve. I think they gave me three numbers…here’s mlss, here’s LT4.0, here’s (can’t remember the last one). None of them were very close to what I could actually hold for an hour.

After LT1 my blood lactate is always going up at an accelerating rate.

So what I’m saying is, LT1 is very obvious on my lactate data. LT1 is very close to my all day power.

It’s hard to tell where LT2 is on my lactate data. Whatever method chosen to identify LT2 doesn’t seem to correspond to what I can hold for an hour.

Is your experience different? Please do expound…if your experience is different that doesn’t mean it’s wrong or anything. I’m just legit curious to know what everybody else’s experience is.

Indeed, and for me the z1/z2 boundary is in the ballpark. FWIW and N=1 and all that. See below for “not formally lactate tested” details.

These were flat out wrong for me, again N=1 and FWIW and all that.

It is why I scratch my head and wonder why a couple years ago some people started using Seiler for coaching guidelines. Respect for him as an exercise physiologist, but IMHO he isn’t a coach.

Same although I’ve only done all-out “all day” (8-12 hours) a handful of times, and have only done INSCYD (no lactate testing). My double century was a little longer than 12 hours, and not all-out, and came in with an IF=0.67 or roughly 67% FTP and the FTP was verified with long all-out efforts (50-70 minutes).

My low-intensity training has HR in 76-82% HRpeak and distributions of different shapes as shown below. Maybe if I average them all out it might look bell curve-ish.

Last week’s 2-hour zone2 with the 3 tall bars 77-80% HRpeak:


and this week’s 2-hour zone2 where there were more excursions above z2 power, the 3 tallest bars are 77-80% HRpeak:


Those HR distributions look basically like the FatMax power rides I was doing a year ago after receiving INSCYD results.

12.75 hour double century (16.5 elapsed time):

This one is rougher… I’ve been paying close attention to breathing and as a rough guess my VT1 is around 138-143bpm or 79-82% HRpeak.

This particular set of Seiler guidelines for z1/z2 boundary seem to correlate well with what I’m doing, although no formal lactate testing to back it up.

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To stir the pot here, my take is that “1 hour power” is not a proper test or definition of FTP (aka power at MLSS), and I think this is why Coggan said ‘about 1 hour’. Time to exhaustion varies, and is trainable. If your TTE is 40 minutes, your 1 hour power will be a fair bit different than your FTP.
As your TTE changes, your ‘1 hour power’ will change relative to your FTP. I think defining FTP as ‘1 hour power’ leads to strange consequences, like TTE at FTP not being trainable, since by definition everyone’s TTE at FTP is 60 minutes.


He says be conservative at 60-65% to ensure you are in Z1. He never prescribed those percentages as LT1.

^ This. Coggan has said repeatedly the range is 40-70 minutes. Age, training history and genetics all factor.

So when you look on your lactate curve, where is that? Ok…you know what you can hold for 40 minutes or 50 minutes, or 60 minutes, or whatever. When you look at your lactate curve, where is that?

Probably because TTE at FTP can be less than (or more than) an hour depending on state of training. MLSS also tends to have some issues depending on the protocol and requires a good about of follow up testing to confirm it using lactate

I don’t know and honestly I’d rather just go out and do a long FTP test one day and then ride for 4-6 hours steady state the next day than have the finger pricks.

FWIW, my numbers are as follows:

  • HR Max: 202
  • FTP: 350-360w at around 180-182bpm (89-90% of HR max) with a TTE of around 45-50 minutes
  • VT1: 260-270w at around 160-163bpm (79-80% of HR max, around 75% of FTP, haven’t explicitly tried for 4-5 hours at this wattage, but I feel 90%+ confident I could do this at a 4 out of 10 RPE and it is also confirmed with DFAa1 results)

Generally speaking, if I ignore the space between 260w and 360w I’m leaving a lot of various workouts that have been incredibly effective for me out of the equation.

On a lactate curve its a value that is steady at a constant work rate over around 30 minutes.

You can’t usually just look at a lactate curve at a specific value from a ramping test and immediately ball park FTP/MLSS. You have to do a follow up steady state test around the specific work rate to look at what happens.

A metabolic cart with lactate and RER will get you in a reasonable area, but the follow up testing needs to confirm it. Which imo seems way overkill unless you really are close to your genetic limits, are a world tour GC pro rider or highly compensated specialist.


Haven’t the faintest idea: I’ve never tested mine, and we’re talking at cross purposes. My point is that to define FTP as precisely 1 hour power isn’t accurate. Coggan said ‘semi steady state’ and ‘approximately one hour’. For some reason, that’s been over simplified to ‘hour power’.

Edit: IIRC one of the key studies on this saw TTEs ranging from c.50 to over 70 minutes. Tbf it’s years since I’ve looked and I need to make the family dinner, so I can’t check now. But assuming my memory is accurate, yes, 50-70 minute range is ‘approximately’ an hour, but I think most of us would agree that 20 mins difference is pretty significant.

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My LT1 was 78%, and LT2 was 89% when measured in 2018. My LT2 correlates pretty close to my HR % derived when FTP testing. So pretty much fits into those ranges.

For my Z1 rides I tend to average around 72% and max around 78%. For the Z3 I try and get the HR above 90% but not push beyond 95% as above that (for an extended period) I take much longer to recover.

I think sometimes people see Seiler’s boundaries and treat them as absolute. In reality a few bpm either way isn’t going make much difference. If my peak during a Z1 ride is 80% I don’t sweat it.

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My LT1 is at 80% MaxHR. And this is based on a conservative read of my La values (when La just starts to rise above baseline, not 2mmol absolute or 1mmol above baseline)

80% MaxHr is right into tempo power zone. Where exactly I don’t know as I do not test for FTP or similar. This does not add value for me … and I don’t really have a proper climb for this nearby to be honest … I do intervals according to duration and repitition, intensity aligns automatically. A far more relaxed approach as this appreciates that form is different on different days.

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I’ve learned (and still learning) a lot thanks to you and others on the forum through a variety of threads. Just wondering how you go through your workouts if you don’t know your ftp? For example the TR workouts which are based on ftp