Calculating LT1 and LT2 approximately without a blood test?

Tr has made no announcement that they will measure hrv directly in the app. (Hence my post above) Even if they did add support it will take awhile to do something with the data. Even if they did something with the data, it’s just one data point so you won’t need it even if it helps get it to understand you better. Plus the data can help train the model so the model can work better for everyone (other things may corralate with the measurement) the same as how everyone doesn’t need to be measured in a metabolic cart to take advantage of the data.

Apple never directly supported ant.

If you want to support hrv just get a polar h9 or h10 as your new strap

This is on the list of things to try and feed into models.

I did a fair amount of DFA alpha 1 training for Cape Epic but I used a separate app with TR at the same time.

We just hired 2 more data engineers who’ve been on for about a month. Basically, it’s just a manner on how fast we can do things. But the team is super smart, they are aware of all of this, and they are methodically working through their ideas.

This makes me think though that we should start recording this pretty soon so that we can have lots and lots of data when we start.

Edit: I just asked if we could schedule doing the work to record this data. The goal would be to start the work to record it in about 2 months.

But that doesn’t mean we’ll hit that as priorities change.


Muscle Oxygen blog has tons of great info, and they specifically reference a collection method in this post that another app upgraded to recently:

" The HRV software needs to first “detrend” the data. This has nothing to do with “detrended fluctuation analysis”, AKA “DFA”. The detrending of RR data is done to remove “stationaries”. These are slow changes in beat pattern from other causes. If they are not removed properly, the DFA a1 will appear more “ordered” than it should be and a bias upward will be seen at very low values (for example a true a1 of .4 may appear as a .6 or higher). This has been the bugaboo of some of the other software approaches including the initial python related packages. For instance, Runalyze was somewhat inaccurate before they enhanced their approach to using the “smoothness priors” approach of Kubios. HRV logger does not use the “smoothness priors” of Kubios fame method either. The issue is worse for recordings with more stationaries of course - so YMMV. We saw very good accuracy with HRV logger in the Frontiers study, but in my personal use, it is not there. After a fair amount of work, Fatmaxxer has been significantly upgraded to use the Kubios method of “smoothness priors” . Despite the calculation load, the speed is not affected even with a re-computation of every 5 seconds"

Original paper referenced for “smoothness priors”: An advanced detrending method with application to HRV analysis - PubMed

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If you guys need specific types of data generated, put out the word. Am sure you’ll get some volunteers, probably too many of us, to help out.


Yah, I think it’s pretty exciting.

I would love to use it to drive aerobic wattage/progression levels.

And if it could also be used to drive Redlight/Greenlight with HRV that would be even cooler.

It would solve a lot of problems in one swoop. And we wouldn’t even have to explain the details to the Athlete. Just do all the heavy lifting on our side and tell them what to do.

It goes with one of our supporting brand promises: We handle the details so you don’t have to.


I just uploaded my data to see what they recommend and it is…uninspiring. The heuristic of avoiding anything with the explicit label AI, is undefeated.

Yes. All you need is the timings now. Well, as long as you have the meta data to go with it so you know if it should be discarded or at least given way less weight if it comes from a source that is likely less reliable. How to process the data is easy to work out later during the summer when you have less data coming in as I’m guessing your app is more heavily used in winter.

If you can start to record the data as soon as you connect to the heart rate strap and for as long as you can after if you’ve seen the work of how workout intensity can be measured by hrv change from before to after. (I.e. there should be data from before you start the workout and after the workout is over). Maybe record a session from the moment it connects till the moment the workout starts and the moment after the workout ends till shutdown or disconnect of the sensor. The server can piece together the three parts so don’t have to extend how you record a workout. The after a workout recording may have to be sent the next time the app is launched to maximize the time you can record and not block the user from quitting. Obviously this change should wait till after you record r-r intervals as this requires a change in the way the app starts and ends recordings.

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The polar HR strap doesn’t give me the running metrics that the garmin does. I got the garmin Pro, but to be honest tracking DFA 1 alpha doesn’t seem really very convenient at all, so I am not sure of the effectiveness. One could track respiration rate in a gentle ramp as well.

Kinda surprised people are spending so much time to figure out LT1, when if youre trying to train under LT1, there’s really no reason to overthink it. I would expect this much discussion on lt2 as that is quite the black box.


LT1 ends up being very relevant, specially when you develop it and it’s very close to LT2.

What you’re describing is something that is not common at all. Care to provide an example from published literature? Only one I’ve seen is in elite marathoners, but never for cyclists.

Yes, it’s not common. Only elite cyclists. But that’s the goal standard we (ppl who ride long distances) should aspire to. I’m sure you understand the constrains of an academic setting, which guaranteed something like this will never get studied. Q

Which is moot since they’ll be getting full metabolic testing.

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Yeah I see what you’re saying about LT1 (not its importance but all the back and forth about how to measure it).

I think a lot of ppl (myself included a few years ago) aren’t actually counting breaths as much as trying to “feel a significant change in respiration”.

Truth is, I never actually FEEL the change in real time until it gets well beyond LT1……like panting level. Not very helpful, and as a result I gave up on the breath test.

Once I plotted breath rate (by actually counting breaths) against Pw:HR it was very clear. I was measuring lactate then and it matched up. DFA matched up as well but counting from one to five for 15 secs and multiplying by 4 is easier than all the other stuff

Now I just count my breath, triangulate with HR and (to a certain extent) power and feel smug. It’s all very reassuring. Lol :joy:

Like all the things we measure, it’s one thing to know it, but quite another to know what to do with it. Train just above, right at, below? How often? How long? What will the internet think?

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Quick hint. You only need to know breaths vs cadence, unless your cadence is all over the place that will be directly correlated to breaths/min.

Like in ERG mode? To clamp HR and power? Otherwise there’s no correlation

200w at 90rpm, my breath rate is different than 250w at 90rpm.

I mean you probably use AI all day every day and don’t realize it. I bet you use Google Search and translation services all the time. And live transcription…there’s a lot.

On the TR side are we not categorizing your workouts correctly after the workout is done?

But, I TOTALLY agree with you that the term is overused and it’s often a bit of marketing thrown on something that isn’t using some version of AI.

I should have used the quote feature, just talking about an easy way to remember breathing rate besides counting for 15 sec and multiplying by 4.

Yes, I would definitely expect rates to be different in those two examples, but I have a pretty good idea what my rr is for most workouts just be gauging against cadence. 6 in 6 out, 3 in 3 out, etc…

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We’ll probably just record one HR stream with timestamps then line them up with a workout after the fact. But yah, we’re on the same page.

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I gotcha now. Yep. :+1:

I was explicitly referencing the service AIEndurance, that after loading my data, populated a calendar with generic workouts 6 days a week for 2 months.

On the AI thing…Im a user and creator of algorithms. I prefer when people use the proper names to call things instead of umbrella labels. For instance, check Deepmind’s description of Alpha go:

We created AlphaGo, a computer program that combines advanced search tree with deep neural networks. These neural networks take a description of the Go board as an input and process it through a number of different network layers containing millions of neuron-like connections.

One neural network, the “policy network”, selects the next move to play. The other neural network, the “value network”, predicts the winner of the game. We introduced AlphaGo to numerous amateur games to help it develop an understanding of reasonable human play. Then we had it play against different versions of itself thousands of times, each time learning from its mistakes.

I wish at some point, you let a lead engineer talk about your system, at a high level of course, It’ll be super interesting!.