LTHR v FTP does not add up

I’m still confused after mentioning elsewhere.
For years I have used my LTHR of 160 BPM as my deflection point based on historical blood tests. As well as this in TT’s I couldn’t hold more like 162 bpm in a 25 or 50mile TT. It went down on 100TT.

In Nov 2021 my Ramp test in TrainerRoad (TR) I made it to 241w and TR decided I was at 185w threshold. December TR got the same result.

Now that I am using 185w by TR That means that my LTHR is at 138 BPM at threshold.
I’m not sure why there can be such a discrepancy.

Thanks

Diesels and long time TTers might find the ramp test underestimates FTP. That’s because ramp tests estimate max aerobic power (MAP), not FTP. And TTers and diesels have a very high FTP as % MAP, and TR uses a fixed % that is too low for anyone with FTP close to MAP.

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How long can you ride at 185W?

And what test were you performing that gave you the measured 160bpm LT?

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@Mgalex If you do a longish interval at 185 w (30 min +), what do you average during the last part of the interval (AFTER your HR has ramped up a bit and has sort of settled at a rate where you can hold that Threshold effort?). Are you saying that is roughly 138 bpm?

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Looks like you under performed on the ramp test. If your LTHR is normally 160 and according to TR your FTP is 185, you should creep up to that HR over like a 10min 100% FTP effort.

Maybe time to do a “classic” 20min FTP test.

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Today I did a session that included a 20 min, ave 185w block that HR was that 136bpm that I can confirm. @liam_mail the test I did was a blood lactate test.
@WindWarrior, I agree with you on the testers FTP. @PhydomiR I may just do that 20 min test!

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I meant what mode of movement. For example, if you did a running step test, that would potentially explain some of the difference.

Did I read your first post correctly - your HR usually averages 160-162bpm on 25 mile and 50 mile Time Trials? What is average HR on 100 mile TT?

@liam_mail I did a test of warm up at 100w then increased 20w every four minutes then each time that section ended I had a finger prick to test the lactate. until I didn’t need to go further.

@WindWarrior I checked and my memory is a little rose tinted. my 10’s were at 168bpm 25TT’s were at 161bpm. 50’s were the same as 100TT was an average of 155BPM and a time of 4h 30 min. I’m not at that level now.

Most likely you increased LTHR while training for TT. It probably dropped a bit, but hard to believe it dropped from 160bpm to 138bpm. Unless you took a very long break and are coming off the couch at 138.

A few articles worth giving a read if you want some background:

And

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Huge thanks for taking the time to find those @WindWarrior

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Had those bookmarked. I’ve taken one month breaks in the past and seen a large drop in ftp, but LTHR only drops a little. After a month off it takes about 2 months to recover most of pre-break fitness.

Well, I thought I’d do a test. 4 min intervals, 20w steps. I managed to get to 196w, 145bpm and after 35 mins. My HR is low so I suspect I’m coming down with a cold. The tissues today confirmed it.