Calculating LT1 and LT2 approximately without a blood test?

How do people approximately calculate their LT1 and LT 2 without a blood test?

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This method was within 5w from my LT1/VT1 derived from a lactate/VO2max -test made in sport physiology lab.


The bigger question is how do you determine them even with a blood test?


Other ways to do the alpha 1 calculations:

This is a notebook with the calculations (helps if you want to reverse engineer it)

Info here and lots more on the rest of the web site:

Make sure you don’t use an optical heart rate sensor sensor, use a chest strap. Connect over Bluetooth, not ant.


I think the inscyd protocol does this? Undercover test: INSCYDs Power-Performance Decoder versus lab gold standard - INSCYD

Here’s my personal theory. I’d love to hear from people with lab values how much this is actually true.

LT1 = whereever you usually ride in a z2-ish way (ie, if you just set out to do a long hour or so, z2 ride).

LT2 = just under FTP


For me Boarstone +2 is ideal workout Z2 indoor workout its mostly on my LT1 or slightly below.
Nasal breathing except when transiting to ride out of the saddle and some HR drift 5-10bpm after first hour.
I can spend 10+hours at LT1-20w, but three hours at LT1 feels hard indicating some kind of threshold to more metabolically taxiing region.
Maybe these can be some kind of indicators of LT1?

LT1 cannot really be estimated well in my opinion without lactate testing. Depending on you personally and your training background it could be low z2 if you’ve neglected long slow distance rides or all the up into tempo zone. Try riding ‘happy hard’ steady state for three days straight for rides of 2-3 hours, no intervals just hold the same power that entire time. If you can maintain the same power three days straight and not feel destroyed, you are probably close enough.

LT2 if defined as 4mmol should be just above your FTP in my opinion. Call it your 20-30 minute power-ish.


So I tried the HR logger app from the article linked above and tested it while performing a blood lactate test this past weekend. It did actually seem to fairly accurately predict my LT2. It was a little difficult to tell because it was giving readings every 2 minutes and I was taking lactate readings every 5 minutes, but my DFA (alpha 1) hit .75 during the same stage that my blood lactate hit 4.1 mmol.

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mmm. I thought DFA 0.75 was LT1.


Yeah, that was a little confusing for me too, but for me at least it was right at LT2? ¯_(ツ)_/¯

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The only thing I can think of is if the 20-30 seconds of me stopping spinning to get a blood draw and reading somehow affected the DFA just right at just the right time.

The DFA alpha 1 should drop to .75 at LT1 and definitely not at LT2.
Which heart rate monitor did you use and exactly which protocol to get the Alpha1 readings.? Also did you connect by Bluetooth.?

Garmin HRM-dual bluetooth. Not sure what you mean by protocol. If you mean settings, I set it at 2 mins and workout just like the article said. If you mean the lactate test protocol It was 15 mins of easy spinning at 100 watts, then 5 minute stages that increased by 20 watts per stage.

The more I think about it, the more I think the brief stopping between stages to take the blood samples must have affected it. You can see how the readings goes up and down.

Ideally you should use either 6 of 8 minute stages so that they align with the 2 minute windows on the logger. Also have you checked the Artifacts Removed tab. Apparently the more artifacts removed the more inaccurate it is. I suspect you are right in that stopping between stages affects it. I’ve found that on a number of occasions that I’ve done this it always comes back with a value of 195/200W with a HR of 140/144.;It does appear to be very consistent but quite a bit higher than I thought it would be. It definitely isn’t easy pedalling at the LT1 it predicts. If you use Twitter there is quite a bit of info on there - just find Marco Altini. HRV4TRAINING and you’ll find it in some of his tweets and retweets.

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Yup, I was having issues with this (using a tickr2). Looked at artifacts removed, and there were a lot. Also, after the ride if I displayed the alpha 1, and selected ‘hide noisy data’, there was no data shown! So my data is all bogus - nothing useful at all. I have a Polar H10 strap coming, as that is supposed to be much better for HRV measurements.

I’ve got some electrode gel to use with my H10 as I suspect that when I switched on my 2 big fans it was drying out the contacts on the strap giving me a lot of noisy data

Glad I saw this as I noted the app is now available for Android, so new strap ordered and app purchased :smiley:

Tests on Monday

This app and science very definitely will not detect LT2, anything above LT1 and the DFA alpha1 figure just stays low.

To ensure remaining truly below LT1 you need to give yourself a small buffer, but having said that, the very occasional dip below 0.75 is normal and shouldn’t impact an aerobic ride much at all.

I’ve been doing a lot of sessions which are just skirting the boundary on the basis that if you’re riding for prolonged periods at low intensity you may as well donot as at a high a power as you can without going too high, hope that makes sense.

I emailed Marco and he said the Garmin HRM-dual I use is equivalent to the H10 and should be just as accurate.

I did a workout today with 8 min intervals at 251 watts(my TR ramp test predicted FTP) and my DFA was around .45 for those intervals. For reference, the results of my blood lactate test were:

FBLA (lactate=4mmol/l) = 233.6
|FBLA (lactate=3.5mmol/l) = 225.5
FBLA (lactate=3mmol/l) = 215.8
FBLA (lactate=2.5mmol/l) = 203.2
FBLA (lactate=2mmol/l = |183.3
Initial Rise of 1mmol/l at 211.2