Calculating LT1 and LT2 approximately without a blood test?

I try to be mindful of all of the work I’ve done over the last 22 years and am certainly aware I’ve had success essentially doing every way of training you can think of. Friel periodIzed, reverse periodization, sweet spot heavy through TR several years back, threshold, now what appears to be more polarized, etc. They definitely all build on each other.

I’m with you though, over the past 18 months I really started to have some physical troubles and as I noted earlier I’m just short of 40. I started thinking about how awful 50 would look if I kept this up and decided a change was needed. The fact that I’ve seen drastic improvements is just a plus to the fact that I don’t feel like absolute hell every morning anymore. My feeling is lots of easy and just a little bit hard is definitely right if you’re playing the long game.


Even for those time crunched, i think you have to ask if a time crunched approach is appropriate for most riders either


Yeah, I heard Kolie on the training peaks pod last week saying that, and fact is he is much more knowledgeable than I am and likely 100% spot on. The problem for me (and likely most) comes in is slightly above LT1 into zone 3 (5 zone model) actually doesn’t feel hard at all. Doing it once, no big deal - doing it several rides in your week and suddenly you’re smashed. That’s a road I’ve driven many times.


But its fun…

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I’m 55 now. Ridden since my dad put wood blocks on the pedals on a tandem. Raced on and off since age 10. I’m a bike lifer. from about 2005 to 2020 was all in on racing. Ended up being a TT focused guy but did a ton of crits, road, some dirt and even a touch of track.

After 15 years all in on mostly SST/Threshold based stuff, I was toast. Some good years, some nice performance. But a nagging feeling that I was working too hard for the results.

Covid hit and racing is on hold and I’m free to try something. Reading the ISM, Mafftone, etc, start thinking there is a better way to skin the cat. That was the impetus for the LT1 stuff. Plus, had the lactate device so why not use it and the data rather than just collect numbers.

I was very surprised how well I responded to the LT1. Won’t repeat the above details but boy it was good. Next step is to do it again and add some volume and actually think about the “stuff” part. For the first time in a while am excited to think about and do some training.

Bikes and stories. They go together!

Ah and on quick edit - No. I don’t think time crunched is really a good or effective thing.


Where do I sign up?! :smiley:

I actually started a “non time crunched thread” a long time ago. Was not really successful, 99% of all postings were from time crunched folks complaining that they are time crunched :slight_smile:


Lets get it going again - I think there could be som much rich discussion about topics like this, recovery, use of longer z2 work, interesting ‘endurance plus’ work etc etc.


+1 for me. I am no time crunched rider, or try not to be ;-).

Another remark on LT1 riding as endurance sessions. also is in favor of doing the Z2 rides in the upper Z2. Also that would give some good gains in the long term. Maybe this is a little bit the same? Because LT1 is not for everyone mid-Z3 :wink:

This is very much the opposite of my experience. HR is affected by a number of factors, but if training is consistent, so is the power I can put out when adequately recovered from workout-to-workout.

A lot of coaches are coming around to riding in upper zone 2, but I would caution against doing all of your Z2 work there, especially if you’re adding intensity elsewhere. I think it is absolutely beneficial to spend some of your Z2 time just below LT1, but you will still benefit from riding at 60-65% for long periods… I favor basing a 3- or 4-hour ride at 65%, then adding periods of 20-30min at LT1 throughout, or even some shorter endurance sessions at LT1.

I wouldn’t want to schedule ALL of my Z2 time at LT1, especially with any other intensity thrown into the rides.


I don’t think we’re disagreeing here. I agree HR is affected by so much and I actually don’t race by it as my primary metric because I get so jittery pre race. For training though, the fact that I’m in the middle of a 70 hour work week or haven’t slept well isn’t reflected in power I’m putting down and it’s absolutely reflected in HR. By going by HR only, I remove the subjective piece of me determining if the power is reasonable that day - I did that, and ALWAYS determined the power was reasonable.

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Intensity of these Z2 rides should depend on the overall training strategy and ability to recover. Doing ISM/MAF style Z2 right at AeT within a POL model is a recipe for disaster. However, staying in a pure ISM model and doing these rides POL recuperation style is probably not optimal either. Management of total load. When doing these at AeT you have to enter them fresh. If you have to force yourself for these total load is to high.

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I’m in a base block at moment. I’m 4 weeks in and will keep it in base till mid March. I see LT1 as a cap but I do tend to ride as close to it as I can. I have regular 1.5 hour up to 2.5 hour loops plus 3.5 to 4.5 hour loops. Currently I’m at average 8.5 hours of riding around LT1 per week aiming to hit 10 hours average per week by mid March.

I used DFA1 to get an indication of LT1. Both via slow ramp and confirmation via steady state. I also pay attention to RPE and talk test / breathing during these rides.

I’m not doing any high intensity at the moment. My main event isn’t till August so I have time to see how well this works before I reintroduce intensity. High intensity will be back in March.

I am due my 4 week retest on the turbo this week. The results of my regular routes is that I’m seeing clear improvements in average speed for the same HR. I am also able to push higher gears and stay below my LT1 HR. I only use power on turbo, so need to look at average speed vs average hr outdoors. Since the rides are ridden in the same easy style, and I’m comparing over the same routes, I have no problems with the comparison. The HR distribution follows same pattern ride after ride.

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So main question… are the DFA 1 alpha estimates closer to VT1 or LT1, as they are close, but still a bit different, as VT1 tends to be higher. I tend to think of Z2 as first rise of lactate to where breathing needs to increase. I don’t have a respiratory increase at first turnpoint.

On my indoor ride yesterday I had 3 blocks of 5min at 205w with 10min recup in between. I put on the fatmaxxer. On my 2 interval HR went to 138and A1 hot below 0.75
On my 3th i put on 195w. HR got 132bpm but also a1 went below 0.75? Is this not strange.

I gave this a shot this morning and thought I’d share the results as an additional reference point for anyone else playing around with this.

I used 10W 6-minute steps beginning at 70% of estimated LT1 (I used the border between Coggan’s zones 2 and 3) all the way to 120% and then used the colab notebook to estimate LT1 via DFA1.

Here are the results:

  • 78% of FTP (as estimated by Xert and Garmin, I haven’t tested in a while);
  • 77% of max HR // 83% of LTHR.

Side remarks:

I took a side bet with myself before running the script as to where LT1 would be and was bang on. I could totally feel it when I hit it. It was still very sustainable, but I had to be focused to maintain the power. Had I let my mind wander, I would certainly have settled on something lower. From that point on, it really felt like I was working and I started to think of TTE in terms of hours and no longer in terms of, hm, days(?).

Each ramp gave me a subtle initial raise in HR. It would then lower and settle for the rest of the interval.

I also noticed that when ramped up so slowly and nicely, MAF heartrate could take me all the way to mid sweet spot. I really don’t think I could sustain that on a regular basis, especially not with any kind of intensity elsewhere in the week.


Same here. 3th approach, good approach? Started with a warm-up of 15min and then every 6min 13W increase. Used fatmaxxer as a real-time monitor and after the session used the runalyze website for another check.

Data looked very clean. 146BPM and 220W. HR is above my Z2 zone and 220W also in my Z3 zone. Indoor FTP around 250W now. Maybe little higher a few months before (260W).
Training near LT1 will not be Z2 easy rides for me ;-). But because it is already high compared to my FTP, don’t know if I can raise the power at LT1 a bit more.


From todays test.
My max heartrate is 184.
My LTHR is ~ 167
FTP 306

Test gave me LT1/VT1 at 150 heartrateisch and 268wattisch

Heartrate is just at where it is calculated at 8020endurance book/website


If you read the paper, a dfa-a1 = 0.75 is already beyond LT1 and VT1. I personally use dfa-a1 = 0.8 as my threshold.

Here’s some crude graphs from a workout this weekend where I wanted to measure LT1 and estimate VT1. I used 10-minute stages and collected blood lactate, muscle oxygen, and breath data. Nothing too exciting except for the blood lactate vs dfa-a1 data.

The first chart has dfa-a1 data from the Runalyze script.

Here’s Altini’s script in Golden Cheetah

For me, first lactate turnpoint is about 165-170 watts. dfa-a1 = 0.8 is about 167 watts. Good enough for government work.