Just to clarify. In the polarized model, most of the athletes studied and used to support the model were doing the bulk of their training below lt1, not just the top of lt1, but below the point where breathing or lactate increased. Ism’s suggestions are different from that, as he’s having people work near the top of what is defined as lt1.
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I am not sure how valuable this information is to this thread, but I was actually tested in Inigo San Millan’s lab here in Denver at the Anschutz performance center back in 2016. You simply paid some money, did a few tests, and were prescribed a training schedule. I was a 35-year-old runner at the time and had never tested any of these metrics despite having a solid running career. I was thinking about training for a fast half marathon. I started cycling in 2019 but had no concept of cycling when I went to his lab. I only did the VO2 max test, but along the way, my zones were calculated based on fat vs carbs. I don’t remember much about the general conversation other than being told not to barf in the mask, but I still have my lab report and prescribed training. I was given 3 prescribed zones: Zone 1-2, Zone 3, & Zone 4+ My max HR was 193. My zone 1-2 was 153-162, Zone 3 168-171, and zone 4+ 180+. Again, this is running not cycling.
A few interesting notes from each zone:
Zone 1-2: Recovery and Base endurance. This is from rest up to your aerobic threshold. This is where your body is most efficient at metabolizing fat for energy.
- Zone 1-2 days should be a gradual increase up to the top workload and heart rate in the zone
- This is your recovery or easy zone
Zone 3: Threshold and Tempo. This is just before your lactate or anaerobic threshold and is typical (sic) the race pace for endurance events. Here is where you build tolerance to exercise.
- Always start with your specific warm-up it’s designed to enhance fat utilization.
- Stay at AT/Zone 2 workload for the entire interval.
- If the Zone workload is giving HRs above the top of zone 2 or below the bottom, report back to your coach.
Zone 4-5 Peak or Anaerobic training zone, it is not an all-out sprint. This is where you improve your peak VO2 and burn the highest calories
- Always start with your specific warm-up it’s designed to enhance fat utilization.
- Zone 5+ or Peak VO2 workouts must stay at Zone 5+ workload and HRs for intervals should be zone 3 and above.
It also suggests strength training days where you complete the specific warm-up before strength routine and do strength training 2x per week. No actual lifting or strength program was ever discussed that I remember.
The Warm-Up Page. Lots of notes here. My specific warm-up was starting at an HR of 143 with 2-minute intervals increasing it to 171 over 10 minutes (143, 152, 159, 163, 171). I was given treadmill speeds for each 2 minutes. Notes on the page:
- Warm-up should be performed on all Zone 3 and 4-5 training days. After your warm-up, take a 3-5 min easy recovery. On your Zone 1 days use the first 8-10 minutes to slowly warm-up.
- If your heart rate after warming up is + or - 4 PBM, please notify your coach. (This was underlined!)
- If at any time you feel like your workouts are too easy do not increase speeds unless you have spoken with your coach. We are teaching your body to favor fat and spare glycogen at the highest speed possible, speeding up to soon will decrease your results.
I was given 4 weeks of training. All included 3 days of base building with one day as long aerobic. Plus a VO2 max day and a Threshold day. In order of each week the workouts were:
VO2 Max:
- 10 sets of 2 minutes (180+)
- 11 sets of 2 minutes (180+)
- 7 sets of 3 minutes (180+)
- 10 sets of 2 minutes (180+)
Threshold:
- 6 sets of 5 minutes, 1:15 rest (168-171)
- 7 sets of 5 minutes, 1:15 rest (168-171)
- 3 sets of 6 minutes, 4 sets of 5 minutes, 1:15 rest (168-171)
- 2 sets of 7 minutes, 3 sets of 6 minutes, 1:15 rest (168-171)
Zone 1-2:
- Simply prescribed time. 2 days at 50 minutes (Running) and one long day at 70 minutes. All HR between 153-162)
Okay, long post, but as it pertains to this thread, this is straight from ISM himself. Although, it’s 5 years old and things could have changed.
I did a DFA a1 ramp test with a Polar H10 and AI endurance and sure enough, my AET came out at 157 BPM on the bike. My anaerobic threshold according to AI endurance was 174 BPM. I have a ramp test FTP of 272w as of December (old I know). My endurance celiing cluster on AI endurance shows 228w and 157 BPM which right now for 60-90 minutes I’ll be right around that probably drifting to the low 160s. I did a ride with a 10 min warm up and a set 215w for an hour and my HR drifted from about 150 BPM to 156 BPM over that time.
I am not an expert. Just trying to provide some hopefully interesting data and information. I think the big take away for me is that this upper zone 2 is closer to what most standard metrics consider tempo. I am also curious that the HR +/- 4 BPM is a concern. Most of my reading suggest HR zones can be 10-15 BPM and it’s no big deal but according to this a small difference is meaningful.
In general, my anecdotal experience is that this all lines up. I can hold 173 BPM for about an hour when throwing down a big climb. I have done 2+ hour rides averaging 150 BPM while it’s an effort, not soul-crushing, and somewhere around 180+ I start to see god (turning 40 much more so).
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So did you end up running a fast half marathon? 
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Significantly upthread I asked “how precise do you have to be?”
It seems ISM addresses that (for Peter Attia) here:
Also, for those of you who have done Steve Neal style long tempo (be it by prescription from him or just based on his podcast appearances), you will recognize this type of training, at least in terms of low intensity.
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So did they basically agree (or didn’t disagree) that top of z2 is 2mmol? Attia said he targets 1.7-1.9 for his own z2 rides at least. Their description of the talk test seemed like they were describing a higher intensity than many seem to describe.
They agree that you have to measure it. It’s not a fixed lactate value that you can apply to everybody. Attia targets that because he measured it. That lactate value is where he sees 1) first rise in lactate above baseline, 2) highest rate of fat oxidation determined using gas exchange. ISM explains that he doesn’t JUST use lactate, or JUST use another measure. He is using THREE measures. Fat starting to go down, CHO starting to go up, and LT1 (lactate initial rise above baseline). He is making the point that he doesn’t just look at the highest point where fat oxidation is occurring and just pick that number (FatMax). He is cross-referencing it with lactate and CHO.
It is a fixed value (more or less, with day-to-day variation) at any given time for YOU as an INDIVIDUAL. It is not a fixed value across different riders. So when you read: “ISM says Zone 2 is 2mmol/L” or “ISM says Zone 2 is 1.7mmol/L”…stop. It’s wrong. That’s not what he’s saying. If you’re familiar with Kolie Moore he likes to call this “fallacy of division”.
Attia goes on to point out that it can be a fairly wide range, so what does ISM do? Answer: targets the middle.
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Their 70-80% of max HR for Z2 is also much higher than your typical endurance workout. I just barely hit 70% of max HR with high progression level endurance workouts.
Yep, the first 500 posts on this thread, when we were all trying to figure that out. LOL. sryke (and others) have said this a number of times: this isn’t easy endurance. It’s not “all-day” dilly-dally pace. ISM even says this in this podcast. Easy endurance is his Zone 1.
My personal experience has been more in line with what BTSeven7 said above (although I do train a bit harder than LT1). I’m likely going to get yelled at for this but he’s prescribing…wait for it…tempo. 
Tempo is the new black. Not that you should actually do it. Do what you want. But it’s cool again…under a different name.
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And couple that with the why, which ISM briefly discusses around 1:12:45…
That from a bioenergitcs point-of-view, he wants to stress the Lactate-to-MCT1 and Pyruvate pathways. Which means from an ISM POV, you can train too low (power level where fatty acids dominate). From my POV its consistent with one of his TP blog articles.
Did anyone else catch that?
My numbers were similar to Attia’s and my 120-150 minutes Tuesday key endurance workout starts around 78% HRmax and I push it up to 81% HRmax by the end.
With only a few exceptions, TrainerRoad plans don’t advocate doing a lot of endurance. Therefore I’m skeptical of AT or PL value for endurance workouts.
Depends on who you listen to? From my POV it never went out of style. I’ve been collecting training plans from the top ‘in it a long time’ coaching companies, and they:
- prioritize endurance training, generally ranging from 60-80% of weekly riding
- advocate doing tempo
- periodize a season and after a long base, move quickly thru build to in-season racing/riding/etc.
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yup, % HRmax is highly individual and why they both gave 70-80% HRmax as a general starting recommendation. And then refine.
Ha that last sentence hit home. I read Skibas new book here and the last few weeks have pushed up my endurance ride intensity closer to 75% with some low tempo sprinkles…it makes me very hungry to the point where I’ve actually started fueling with carbs during endurance rides where before I didn’t feel the need to.
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Are you eating during those workouts? At 270-ish ftp and adding warmup/cooldown that is a 2.5 hour workout for me, and burns 1600-1800 calories. I’m absolutely fueling those workouts at 500-700 calories of things like Cliff and granola and fig bars. My coach advised eating vs my previous liquid carbs, and I found it helped.
Yeah RPE and ‘hard’ is relative, I’d say that 75% ftp takes focus and feels like a strong/robust workout. Guess I could call that hard for an endurance workout. Easy for me is 66-69% ftp, that’s what I target if feeling off from outside stress including allergies.
Without lab testing its all part of a puzzle you need to solve, for yourself.
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Why? Part of the benefit from my point of view is wearing a groove in pushing 200W (average or normalized) for 130 minutes. I’ve played a little with different fueling, and without lab data the only difference I can tell is recovery and ability to support doing 6 hours Mon-Wed, and another 4-6 Fri-Sat.
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Not a good idea. That can cause a lot more stress to your body.
Depends on the body size and power but you need to fuel z2 like normal.
Solid foods are possible so a bit nicer than drinking gogo juice.
Z2 means >3hours of course.
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Nscyd prescribed tempo to lower vLamax, or… “medio” right?
It’s a long and complicated road to get from an activated signalling pathway to actual performance improvements. Plus anyway if you’re going down that rabbit hole it appears that low end-session muscle glycogen is more important than pre-session or withholding carbs for the first part of the session
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I’m chasing overall performance. The signaling discussion is a bit off in the weeds, at best a marginal gain. I’ve experimented quite a bit with morning workouts and only fueling after 1-2 hours and/or completion. Have not been able to see any performance difference in my data.
Since this is an ISM thread, I tend to focus on the big picture that ISM writes about here:
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Yes. Feb 2019 for me. Even though I understand the skepticism that tool has garnered****, it was the first time I considered the notion of riding low-mid tempo deliberately and as a central part of my training. So it was an important step for me. I joked with my roadie buddies that I trained “like a triathlete” because at the time the only TR workouts I could find at .75-.80 IF were in the triathlon plans. LOL “How is this EVER going to improve my FTP?”, I worried.
I later refined it with Steve’s ideas and then various consults and informal discussions like this one (usually with older riders who often jokingly and semi-condescendingly said: “you know that’s just tempo, right?”).
What also happened quite a bit in 2019 was much discussion about “gray zone” this and “no man’s land” that. “There are no magical zones, dear athlete, except the one I use in my coaching plan” LOL. Anyway, I’m not bitter much. I know we’ve beaten that horse to death. Just glad I finally figured out what works for me.
*****my vLamax was already .22. Despite not “needing” to lower it, I did medio work anyway. Besides the first year I rode a bike, biggest fitness improvements I’ve had…but not because of Inscyd per se…cause tempo…I guess Or all of it.
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Since January 1st I’ve been doing endless rides on county highways with cars flying by at 60-80mph. But there is a large shoulder and the Varia radar helps alert me to move over and puts me over 6’ from traffic.
Without a top tube bag I’m beginning to prefer bibs with mesh pockets, maybe I’ll get a top tube bag some day. All of my winter bib tights have pockets. Only 1 pair of summer bibs have pockets. I’m going to buy more of the summer bibs with pockets (also handy for carrying a pump!).
What I do before a ride is quickly guesstimate calories needed based on ride, cut off the top of my Cliff/granola/fig bar wrappers, and put into either my jersey or leg pockets. During the ride I grab one, take a bite, and return my hand to the bar. No real skill to hold the food with hand on handlebar. Empty wrapper goes back into the bottom of the pocket. Leftover food goes into a ziplock in the garage, for the next workout.
I’m only using liquid fuel on longer 4+ hour rides, or harder 3+ hour group rides. Below that my stomach prefers separating fuel from hydration, and my ftp is not high enough to create fueling challenges on 2-3 hour rides.
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Makes a lot of sense. I know you’re no longer using TR for training, and I can understand why given your experience and perspectives. Thanks for sharing your knowledge here. For those of us that don’t invest the time in really digging into the science and how one’s body responds it sure is challenging to decide what voices to listen to in working on personal performance. Your three bullets make a lot of sense. Thanks!
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