Calculating LT1 and LT2 approximately without a blood test?

The hard part is they aren’t “media trained” and might give away secrets. Maybe we could do something one day pre-recorded and then edit anything out we don’t want. That could be cool.

But even being aware of some of the systems that we use would give too much away.

As people here probably know, ML is a combination of data + technique. The actual “ML” part of it (mostly) uses off-the-shelf products. There are some companies doing their own crazy custom ML stuff (google, tesla, etc) but that isn’t us.

The real trick is what you feed into it and how you chain it together.


While I’d love to better understand how your system works I don’t see how you could explaining it without giving away too. Unless you’re so generic that it doesn’t really mean anything from a technical standpoint.

I feel like feeding in the raw ride data in would be too noisy to train the model well so the interesting part is how you process the ride first as that would have the greatest impact in the model training. A 19x19 matrix where each position can only have three values is much simpler then a ride that has 14,400 data points per hour where each data point is around a byte in size and has to scale to all users. (Well you could be paying for lots of time on NDm A100 v4 machines…)

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Another approach is to have a real model, say like WKO5, Xert or any other derivative of CP, W’……Without a model you end up with the problems of medicine where the stats of the population don’t apply to the individual.

I’ve tried that but the actually act of counting seems to focus my mind on it and I start to try and breath “better” ie slower and deeper. And then I forget, or something distracts me and I start to breathe normally again and then I start counting and the cycle begins again. Not conducive to good data.

Someone (LOL) Wrote: "I did this exact experiment a couple of years ago with the same kind of results. After 6-7 weeks of this training, I was breaking Strava PRs left and right and riding stronger than ever. I continued this type of training for 13 weeks, peaking at 13 hours per week, and unfortunately didn’t see further gains.

I’m happy with the experiment but really wish I had switched gears to a sweet spot or threshold block after the 7 weeks.

This kind of training definitely increased my durability and overall endurance"

Quoting the larger amount of text as we have a few different topics now in this thread (all enjoyable).

This observation is interesting. As a generic interpretation for discussion, 7 weeks productive, next five perhaps less so. Can’t say I did the same experiment, but by chance, after a few months, I decided to add some VO2max along with some harder “race-like” days. In effect, I went from the LT1 focus to more of a twice a week hard focus.

It worked pretty well. By end of summer I was hitting historically solid 20 min power numbers and had a very solid MLSS / FTP test that went for about 50 minutes at low mental stress (RPE) for the wattage.


Since that time have been wondering on how to be more purposeful and how to block periodize the work. I’m in Mid-Atlantic, we have winter. It might be great to do the LT1 stuff on trainer, but too boring. Am looking at something like this:

January + February: SST based indoor training
March + April: LT1 focused aerobic build

May: VO2 block (Empirical Cycling style)

June + July + August not sure what I’d do next

Probably into the twice a week hard approach and more riding than training. Meaning Tuesday Night Mountain Bike throw down, and either a really stout group ride on Saturday or a race.

Curious what you guys think. Should comment that my riding now-a-days is a lot more about being fast enough to have fun when the weather is good as opposed to peaking for an A-Event.

Anthony (AJS914) wrote that, not Brian!

That was my first LT1 experiment. All that training was actually 5bpm under LT1 because I chose 120bpm back then.

The other thing I noticed was that when I first started, my 120bpm speed was around 12mph. Painfully slow because I was used to cruising around at maybe 17-18.

That 120bpm speed eventually climbed to 17-18-19mph.

I’d think about doing VO2 in March (maybe just two weeks is plenty) after your Jan/Feb extensive TTE work. Then do your LT1 work with some weekly maintenance intensity thrown in.

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Simply structure your training in such a way that you enjoy it the most. It won’t make a difference (for your goals) if you start SST and progress with LT1 or the other way round. Simply do some/the work. Consider progression.


Apologies - I confused the attributes!

Yes, I had considered the VO2max block earlier.

Sryke - Yes, agree.

It’s become more about attention span than optimization. But I like to have some purpose. As productive as longer LT1 is, during Jan-Feb its all trainer and I’m more interested nowadays less in optimization and more about 45-75 min of useful work and getting off the trainer. My days of 2-3 hour trainer rides might be in the rear view mirror.

FWIW… this season I’m doing LT1 and weights Jan + Feb. When weather starts getting good in March and April will start turning pedals harder.

As long as it can easily handle the r-r timings from a fit file too as garmin head units can record r-r timings. Would be useful to get this same info for outdoor rides. May as well try and use as much of the same code path for both data sources


I enjoy going down the rabbit hole of various training methods, but this nails it for 99.9% of amateurs even up to the low level pros - I think. Set it up so you enjoy it, and if you want to race well you’ll have to go hard sometimes, but most should be enjoyable. And If looking to improve, try to find a way to get more time doing the enjoyable stuff.

Obviously a pretty big oversimplification, but it’s really not complex for most amateurs.

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I believe this need for complexity is a direct consequence of indoor riding or bad locations for outside riding. When the riding is boring you need to spice it up with structure and creative workouts.

Is this a time when you can ride outside more? If so, I would combine “LT1 focused” and “SST”…fun to do w/ outside rides. For example, 2 x LT1, 1 x SST, 2 x mid-Z2 endurance. On that SST day, maybe do “lactate clearance” O/U to mix it up.

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Got a CTS email in my inbox last week on The Role of Zone 2 Training During Indoor Cycling - worth a quick read IMHO.

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So its been a few years since this discussion was started. Anyone with LT1 and Xert LTP data to compare? I know that theres a few coaches starting to measure those over on Xert

I estimated LT1 at 210w from my ramp test a few posts up. Xert has it at 213w, with an FTP of 270w.

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Really depends on what his goals are. Lots of ways to go after raising VO2max - aerobic build into FTP work, high power lactate clearance/tolerance, anaerobic work. Just depends on what the athlete wants/needs.

The thing I’m finding more and more about this stuff, and even FTP, etc., is using the data to inform “feel”. HR and power (to a lesser extent) will change with a lot of different variables, and sometimes with these tests we are splitting hairs trying to determine if LT1 is at 200 or 205W, when your power meter probably isn’t that accurate. I’m not convinced coaches should be measuring quite so much, when some blend of the empirical and the subjective is probably the right answer when it comes to both testing and day-to-day application. Educating athletes on RPE (not the numerical value, but the actual feeling of certain intensities) is a big part of coaching, IMO.

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I’m just looking for evidence to tell me my kinda hard kinda fun long rides are doing it right haha. I used to keep endurance rides strictly in middle zone 2 and they were boring. Now riding at low zone 3, especially with “stuff” thrown in like a lot of the pros are doing is making endurance training enjoyable.

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Agree. He solicited suggestions. That’s what we were doing.

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Here’s my data:

And a couple of recent rides:

Most recent Ramp Test (Feb. 1):

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