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 youāre 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 periodsā¦ 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 wouldnāt want to schedule ALL of my Z2 time at LT1, especially with any other intensity thrown into the rides.
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I donāt think weāre disagreeing here. I agree HR is affected by so much and I actually donāt race by it as my primary metric because I get so jittery pre race. For training though, the fact that Iām in the middle of a 70 hour work week or havenāt slept well isnāt reflected in power Iām putting down and itās 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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Iām in a base block at moment. Iām 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 Iām 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.
Iām not doing any high intensity at the moment. My main event isnāt 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 Iām 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 Iām 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 questionā¦ 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 donāt 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 Iād 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 Cogganās 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 havenāt 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 donāt think I could sustain that on a regular basis, especially not with any kind of intensity elsewhere in the week.
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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, donāt know if I can raise the power at LT1 a bit more.
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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
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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.
Hereās 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.
Hereās Altiniās 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.
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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 Iām 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.
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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 weekās Z2 workouts to this value. So far have done 2 tests:
- as last workout during 2week VO2max refresher block (146bpm ~ 165W)
- rest week, and now during 1st week of Sweetspot progression block (153bpm ~ 185W)
It is quite a fluctuation, letās see how it progresses over base phase.
EDIT: sorry, i probably misread your post. @Bigpikle interpretation seems more to the point 
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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.
Dan
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 canāt 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
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Itās 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 thatās 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) 
Nevertheless, Iāll keep my cool and see where it takes me over next 12 weeks.