All the Seiler you care to listen to on Inside Exercise cast

That sounds correct, and actually they discussed this briefly on the podcast.

But to me this is not two different camps/theories…but there is one grand unifying theory at work here. Seiler’s work that observed the 80/20 intensity distribution was done on a different set of athletes. To be competitive on a national or even regional level requires a level of training that requires that level of intensity distribution.

But let’s do a thought experiment…if a cyclist is training 30 hours a week (not an unusual load for a professional cyclist)…and following an 80/20 intensity distribution…about how many hours will be intense work? About 6 hours.

Now, would the averge pro cycylist be doing 10 intense hours if they could? Yep. For sure. But 6, 7, 8 hours is just about all the human body can handle. So the pro cyclist is doing what a pro cyclist’s body can handle intensity-wise & filling in extra training with less intense work because they can absorb the training & the training still provides enough stimulus that there is adaptation.

The weekend warrior is just doing the training the elicits the most adaptation first. The 6 intense hours. The other 24 hours of training is super easy. So easy that the weekend warrior doesn’t even train at all…but to the extent that additional training happens it should not be intense.


Yep. All that.

I think this is only part that Seiler would disagree with (I don’t have an opinion because I don’t know enough to say). If at least some of that time (likely a single session) isn’t taking advantage of the benefits that only come about via duration, then you haven’t elicited the most adaptations.

To me this suggests that for some types of adaptations there is not a one-to-one correspondence between intensity and duration. To put it in TR terms from 2018: “try to do that long ride on the week end guys, but if you must then SST”. There was low compliance (I think) because: yes, time constraints, but also the thinking “I can substitute one work for another”. Even worse, I can base it on TSS.

Here’s what is still unclear, and I think drives ppl nuts about Seiler (or at least this part of the message): so WHAT ARE the adaptations that only come about via duration? Or is it just the “same ones” but more of them?

All roads lead to Rome | Tokyo because in elites they are getting all of it if they stay healthy, etc. so why try to tease it out (for them)?

1 Like

Easy to listen to him, but I expected more.

Before I ever heard of Seiler, I bought plans from some coaches and coaching companies. Some of Seiler’s research is at the end of a chain: Coaches > Athletes > Seiler. I’d rather go to the front of the chain and get a plan the coaches.

I’m old enough to remember long slow distance training from the 1970s.

Hmm, in 15 months, at an even older age, with less athletic credentials and no real knowledge of training or exercise physiology, I took myself from spin classes to 272W one-hour power and high anaerobic repeatability.

on my best hour attempt, the first 1W drop-off in average power was at 69 minutes. All hail Aeolus, Roman god of the wind :wind_face: and my training mentor! :rofl:

80/20 is on sessions, not on time … just saying :slight_smile:

And it was “established” on sports where training twice a day is pretty common. A 30min Kenyan shuffle in the afternoon counts as much as a 2.5h long easy run.

Yes. I have a rough structure/idea based on where I am in the year. I try to meet my training goals based on how I feel (and life and weather). I adjust my goals based on “how I feel” (and life).


The research was compiled on a per-session basis but not because that’s the correct way to think about it…the research was compiled that way because that’s the way they were constrained to do it.

Here is the bottom line: an athlete’s body can only digest a certain amount of high intensity training over a given time frame. Doesn’t matter if you break it into two workouts. That’s corollary #1.

Corollary #2 is that athletes get more adaptive benefit from high intensity training. That’s why they do as much high intensity as they can adapt to & then fill in with lower intensity work. Not the other way round. Nobody is doing 20% of their workouts at high intensity because they just can’t handle any more zone 2 work.

Corollary #3 is that a typical human with reasonable fitness can absorb about 6 to 8 hours of high intensity every week.

And that is Brennus’ Grand Unifying Theory of HIIT & Polarized training.


What do you consider high intensity?

There you go. Done and dusted. :joy:

look closely at IF, basically all but 2 are above .9 IF. And then check out all that unplanned time off. But hey, 3 weeks later I had super compensation kick in and pushed my 68 minute power to 271W.

School of Hard Knocks! Yes, I’m a knucklehead.

1 Like

I’ve already posted multiple times, so this is the last one because clearly @redlude97 is not going to be making up songs and singing about my exploits.

Corollary #1. Yup. However I believe it was possible to do more high-quality hard work by splitting it into AM and PM workouts.

Corollary #2. More adaptive benefit of HIIT? Sort of?!

I’ve taken 2 paths to push a 275W ftp, one easy in 2022-2023, one hard in 2016-2017. Basically ended up in the same place. Data below on corollary 3.

Honestly I’ve been surprised by the amount of adaptation from low-intensity work. Really surprised. Really really surprised. Really. Did I say surprised? LOL.

Corollary #3. 6 to 8 hours of intensity every week? I’m not the only one to read “high intensity” - are using a 2 zone model?

Here are two times when I have good model data in WKO, showing weekly time at high intensity estimates over a build and transitioning to Wed worlds ‘racing’


(it looks almost the same if I use high HR instead of % estimated/relative vo2max):

Last column is time at high intensity. Never exceeded 102 minutes in a week. Not even 2 hours, and definitely not close to 6 hours. But yeah, you probably meant anything about zone2 / lower aerobic threshold.

And this year:

just twice I’ve touched on 30 minutes of high-intensity in a week. But visually it looks like more 9+ hour weeks during the Feb/March/April build.

Weekly 3 zone time at intensity, then:

and now

VO2max estimated then 4.24 L/min and now 4.22 L/min.

Performance wise, will I haven’t worked on 45/60 minute power this period. But I have done some pacing efforts at 20 minutes and under that beat (in red) my fifty-five year old self in 2017:

Completely convinced I could crush some more power PRs if I actually went for it more often (like I was doing in 2017).

Since I’m not young enough, gonna have to say newbie endurance gains are possible without a lot of intensity. But when I do intensity, its not some % ftp repeatability game. Its a full gas, listen to the body and go hard intensity game. Had that same mindset 6 years ago, that hasn’t changed. Just finding that less is more, probably because of age.



Corollary 1: Kind of. You get different adaptations for training if your muscles and liver are glycogen depleted versus not. The size principal also says that two a days let you get more time per day training smaller fatigued muscle units instead of the large muscle units taking over as the smaller fatigue.

Corollary 2: Some adaptations are better trained at high intensity, but even high intensity performance has a high aerobic component. And aerobic performance is mainly trained via low to moderate intensity (threshold and lower).

Corollary 3: They can do so for a while, but they will most likely burn out in less than a year, especially without enough quality lower intensity work. I think Seiler is more right than wrong on this one. You can’t get around having the aerobic fitness to allow you to do the high intensity work well.

Lol just kidding around. FWIW no knock to Seiler, I’ve said it before, anyone with motivation can push out time at threshold. Just finished the Inside Exercise pod and :man_shrugging:

1 Like

I know what you’re trying to say: “Gotta SweetSpot, bro”.

Kudos, my friend. Kudos.


Could it be a causal relationship here?.

Have you ever ridden 6-7h ? Have you done it with several other people?. Have you pay attention to their performance after the 4th hour?..…there’s your answer.

1 Like

It’s all the same path my old friend, there’s only one BBarrera. Brains are good at creating narratives. In endurance training it all adds up.

Pressure and time, my cycling friend, pressure and time.

I actually followed a Seiler prescription as a base phase one year - 6 hours ramping up to 13 hours per week of noodling around at 120bpm plus one day of intensity. I was making PRs by week 8.


Yeah I do that every 2 months or so. Still doesn’t answer the “what’s the adaptation(s)” question. It just answers the “it works” question. The adaptations are myriad and overlap significantly with those achieved via high intensity, which is (at least part of) Brennus point

Since you haven’t fully read the thread I’ll quickly summarize what we’re actually discussing: all of it works, but as a thought experiment why not just do the six hours of intensity if you only have six hours?

Responses so far:

  1. Sounds like good logic
  2. There might be some benefit from duration independent of intensity (Seilers point)
  3. Yeah but that would suck (burnout, mental, etc)
  4. Really only helpful for amateurs (pros don’t need to tease out any hypothetical difference)
  5. That’s not fun
  6. That’s way more interesting than just riding around a lot.
  7. Why do these discussion have to devolve into….etc
  8. Real talk: six hours ain’t gonna get you far anyway, prioritize fun

Well maybe there is a Special Case to the Grand Unified Theory (G.U.T.) that might shed some light on this thought experiment…

First of all, I think there is plenty of literature out there exploring whether or not moderately trained athletes achieve superior adaptation from a few hours of high intensity training or a few hours of sub-VT1 steady state. So you can get a clear answer to that question with a cursory review via pubmed.

Second of all, the Special Case, if the athlete in question is largely untrained or mostly de-trained then for the first few weeks JRA will do just fine. Just get out on the bike. You’re going to see fitness gains. Whether you ride Z2 or throw in some more structured intensity.

Eventually you get to the end of that rope & the athlete requires something more to stimulate adaptation. Add some structured intensity. You can continue to turn up the ‘add intensity’ knob and reap some gains all the way up to 6, 7, 8 hours of structured intensity work a week. If you think you can’t achieve enough fitness in this manner to do large events…then WTF are you doing on this forum? Ha! :rofl: That’s practically a TR Proverb…you don’t need long hours to do long events. (of course my pos’n has always been that’s true but you need to do some long hours to DO YOUR BEST at long events)

Now we are at the end of the G.U.T. Special Case. :smiley: If the athlete wants to continue progressing, adding intensity gets dicey. Some can go all Zatopek on it and continue adding additional hours of interval work. Most can’t. So you have to find hours on the bike that induce adaptation but not overtraining.

The thing that provides enough stimulus to induce adaptation but not so much stimulus that the athlete can’t recover…that thing is sub-LT1 training. You can do a lot of that which is good because it takes a lot. So keep the 6,7,8 hours of structured interval work & start adding sub-LT1 training.