Calculating LT1 and LT2 approximately without a blood test?

Did a LSD ride yesterday and was for most of the time above 1, although I was around 140bpm of 195 as max.

Not sure if the is working for me.

I also have 195 max and my LT1 is around 140

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did you mean DFA-a1 was mostly above 1 at that HR?

If so then I’m not surprised. My max HR is 188 and HRV Logger and Fatmaxxer both put my DFA-a1 point at 154bpm. Thats well into my tempo zone usually.

Yesterday I did some 100% FTP intervals and an extended cooldown. A minute or 2 into the cooldown I thought it might be interesting to see how DFA-a1 might be affected by all the work done during the main session so fired up Fatmaxxer and watched the results. The HR for 0.75 was the same as during the step test, but obviously the power that hit that caused me to hit that HR was significantly lower after the intervals.

Just confirms that obviously on longer or interval rides you need to take into account the drift in power:HR over time and pay attention to HR rather than just the power numbers.


If I get it right, intention of doing LSD at or under LT1 HR is to minimize accumulating fatigue over longer period. You might not see effect after single workout. Rather cap all your LSD rides with LT1 HR and then compare your fatigue just before going into recovery week.

I myself am not interested in realtime HRV dependent capping. Will do every week one test, calculate HR with DFA a1 and then cap rest of week’s Z2 workouts to this value. So far have done 2 tests:

  1. as last workout during 2week VO2max refresher block (146bpm ~ 165W)
  2. rest week, and now during 1st week of Sweetspot progression block (153bpm ~ 185W)

It is quite a fluctuation, let’s see how it progresses over base phase.

EDIT: sorry, i probably misread your post. @Bigpikle interpretation seems more to the point :slight_smile:

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So just did a little ramp test. Started at 90w for 4, then 10 more for another 4 min. After I reached the end of Power Zone 2 of 7, I went into VO2max mode.

FTP somewhere around 200.

My Alpha 1: Only got close to the 0.75 when I was actually at what I consider FTP.

So I have my doubts that DFA a1 of 0.75 reveals much about my LT1. Maybe LT2.

Using a Polar H10 via BT.


Maybe try longer ramp steps, like 6 or 8 minutes? According to DFA a1 FAQ, start with 20min warmup and only then start logger with first step. Keep increasing power with 6min/10w steps until value is clearly below 0.75 and then continue with another step to confirm that you really are below 0.7 and previous step was not temporary fluctuation.

Created workout with this protocol (Log In to TrainerRoad). If can’t access it, then it looks like this:

Warmup step is at 50%, each step +4% and final step is 82%. I start logger with first step and stop at last, before cooldown. Nice and easy workout between SS days :slight_smile:

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It’s recommended to include a step where you cross threshold. There are ppl with LT1 very close to LT2.

Thanks a lot, will try next week.

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Unfortunately that’s not the case for me personally, calculated LT1 is at quite low Z2 (~65% of FTP). This is weird, because outdoors I usually ride 4-6hrs at 70-72% of FTP with zero cardiac drift and at suggested HR cap it is even negative -1.4% for 2-3 hours (indoors) :man_shrugging:

Nevertheless, I’ll keep my cool and see where it takes me over next 12 weeks.

yep - definitely do longer . steps to allow levels to stabilise. Marco suggests 6-8 min steps and every time I’ve seen people here use shorter steps they also seem to get strange numbers. Have a look at his suggested protocol in this post.

For all of these tests, very much need longer times at each step. Throw away anything you have read or done with three minute lactate (or other) tests with short times at each power level.

For LT1, this power level is well within the ability to ride for a long time. Set up a workout with 8-10 min steps with 10 watt changes. Do the ride as a workout and get good data.

For example, if you think your LT1 is 180w and you have an FTP around 240-250w, then plan to ride steps at 150-160-170-180-190-200-210. That’s a good workout and you should get good data.

FWIW, and slight tangent, even the classic ten min steps MLSS test aiming for -10w, MLSS, and +10w as a bracket doesn’t work well.

I don’t like to test much. So if I’m going to test, I try to make the protocol rock solid. Saves time in the end.

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I recommend you guys do this test by HR rather than power.

You can start with an estimate. San Milan suggest the talk test. Seiler recommends 65% of HRmax.

Warm-up, get your HR in that range and see where DFA a1 is. Go 5 beats higher or lower depending on the reading.

Once you find your DFA a1 heart rate, you are there.

I’ve found that actual power at DFA a1 will fluctuate with freshness. If I’ve had a rest days or some easy riding prior, I’ll get a higher power at DFA a1. If my legs are cooked, I’ll put out 20-25 watts less at DFA a1.

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Phil, 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.


in my DFA Alpha 1 records i can see some extrasystoles, especially when my puls / power changes (goes up or down). In this example i did a 3 minute All-Out effort.
The green line is the power output, and the black dots are the RR-Intervals (millisecounds between heart beats).
Still have been at the doctors and everything should be ok so far with my heart. Extrasystoles are “normal”.

Anybody of you recognizes something like this?

New data field

available for 520 Plus, 530, 820, 830, and 1030 variants.


Thought I should point out that alpha 1 isn’t just for finding lt1 threshold but can also be useful to track fatigue

Another reason why I’d love tr to be able to do the recording and calculations in the app to help train the model. (Not saying it should be exposed in the UI as I do see the issue with overwhelming the user with data for those who aren’t data geeks)

Also implemented here:

@Nate_Pearson what’s the chance you could do this in tr? Could be useful for red light/green light, well to end the workout early or flag that the prediction was wrong if they got a green light


Doesn’t TR need to be recording RR interval first? I thought that they had updated it to record it, but I didn’t see it when looking through the settings the other day. My .fit files exported to garmin don’t have it, so Kubios cannot do any analysis on the TR files.

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these are too vague or too low. Better to do the ramp test.

This is true and very key, but with enough long sample you get a sense of the range.

They don’t. This is not really a simple ask as getting good data isn’t simple.

-have to use ble over ant+ (so need some way to tell users which option they should pick which is more a UX problem)

-have to identify which strap is being used to record with. Mix of a UX problem in telling users which brands they should buy and a data issue to handle the data from different sources differently

-positioning the strap is not so easy. Need so way to inform users that while they get good hr data their hrv needs better positioning

  • with recorded data need to flag if it has bad data in it so should be ignored

That’s all before doing the actual calculations are done

does apple support ant+? Samsung does not any more, so I needed to upgrade to a Bluetooth strap just to get hr data after upgrading from my old s7. I say this since tr is talking about using hrv, but the reality is that they are probably a long ways off.