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Home > Forum > Triathlon Forum > When is your LTHR not your LTHR? When, why, who changed the LTHR Calculation?

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When is your LTHR not your LTHR? When, why, who changed the LTHR Calculation?
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FlashBazbo
Jul 2, 18 7:27
Post #1 of 10 (1538 views)
This is probably an odd situation. I've been training and racing seriously for a long, long time. Probably 8 or 10 years ago, I tested to determine my LTHR. Knowing that LTHR doesn't change much over time, and never feeling that my zones were off kilter, I never revisited the issue. I set it and forgot it. Whenever I tested and reset my FTP, my Power zones and HR zones tended to line up pretty well.

This last weekend, I did a FTP test and, on a whim, used the data to re-determine my LTHR. (My HR was in "old" zone 5.2 throughout almost the whole test.) My "new" LTHR is somewhat lower than what I have been using for years -- about 10 bpm lower. The difference isn't in my average HR over the 20-minute test -- that's EXACTLY the same as it has been for 8 or 10 years. The difference is in the calculation based on the data. The number crunching has changed. All my HR training zones have been moved by about an entire zone level!

So, when did the LTHR calculation change? (I notice a difference between the first edition Cyclist's Training Bible and the current edition, but I'm not sure what calculation I originally used.) Why was it changed? If it is better, why is the new calculation better?
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Re: When is your LTHR not your LTHR? When, why, who changed the LTHR Calculation? [FlashBazbo] [ In reply to ]
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jaretj
Jul 2, 18 7:49
Post #2 of 10 (1517 views)
We're going to need to know a little more about how you tested and who's test you used.

If you used someone's protocol from 10 years ago and changed to a different protocol, it wouldn't be out of the ordinary to see a different result. You would just use the training plan that corresponds to the testing you just did.
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Re: When is your LTHR not your LTHR? When, why, who changed the LTHR Calculation? [jaretj] [ In reply to ]
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FlashBazbo
Jul 2, 18 8:09
Post #3 of 10 (1500 views)
jaretj wrote:
We're going to need to know a little more about how you tested and who's test you used.

If you used someone's protocol from 10 years ago and changed to a different protocol, it wouldn't be out of the ordinary to see a different result. You would just use the training plan that corresponds to the testing you just did.


Good question. I SUSPECT (but don't really remember) that the number I've been using (the "old" number) was based on maximum heart rate. That number was almost exactly 90% of my maximum heart rate. It came to 167 bpm.

My new calculation is 95% of my average heart rate over a 20-minute time trial. My 20-minute average HR has been 166 +/- 1 bpm for a long time, including this weekend. .95 x 166 = 158

My training plans are thoroughly current. But another key fact: One reason I did the recalculation of FTHR is that my FTP number went down and I suspect overtraining. If 158 is a good FTHR number and I've been using 167, that could be the problem (or at least part of it). It is entirely possible that the old formula was bad or I made a mistake in calculating the number way back when. I just need to figure out if 158 is a good number now.
Last edited by: FlashBazbo: Jul 2, 18 8:23
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Re: When is your LTHR not your LTHR? When, why, who changed the LTHR Calculation? [jaretj] [ In reply to ]
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FlashBazbo
Jul 2, 18 9:13
Post #4 of 10 (1445 views)
Okay, let's throw in another data point -- probably the conclusive data point and one I should have already checked. I just checked my Training Peaks files on all the time trials and road race breakaways I've done in the last two years. For all all-out efforts I've logged between 30 minutes and 1 hour in duration, my average HR has been 162 or 163. Remarkably consistent. That's about halfway between my old LTHR number and the new one. I'm assuming 163 is the correct LTHR for me, then. Correct?
Last edited by: FlashBazbo: Jul 2, 18 9:34
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Re: When is your LTHR not your LTHR? When, why, who changed the LTHR Calculation? [FlashBazbo] [ In reply to ]
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jaretj
Jul 2, 18 9:45
Post #5 of 10 (1426 views)
That last HR you described is likely what I would use as a LTHR if I was training by HR.

But again, I would use the HR test from your current plan. If you current plan is guided by Power then I wouldn't worry about HR and go by Power.
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Re: When is your LTHR not your LTHR? When, why, who changed the LTHR Calculation? [jaretj] [ In reply to ]
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FlashBazbo
Jul 2, 18 9:57
Post #6 of 10 (1407 views)
I've been training by Power for a long time, but that doesn't make HR irrelevant. In simplified terms, for a long effort, HR tells me how hard I'm working. Power tells me how much I'm getting out of that effort. The combination of the two tells me whether everything is working as it should be.

A couple weeks ago, I raced up a long mountain climb. As I looked at my Garmin on the way up, I noticed that my HR was where I expected it to be, but my Power output was lower than expected. Having both measures in front of me told me that I had an issue that I needed to resolve. If both aren't accurate, I lose that diagnostic capability.

Thanks for the responses.
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Re: When is your LTHR not your LTHR? When, why, who changed the LTHR Calculation? [FlashBazbo] [ In reply to ]
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jaretj
Jul 2, 18 10:09
Post #7 of 10 (1396 views)
I am not here to argue over Power vs HR training, each has it benefits.

You have a disconnect from your HR and your Power which cannot be explained with the information provided. I can only speculate.
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Re: When is your LTHR not your LTHR? When, why, who changed the LTHR Calculation? [jaretj] [ In reply to ]
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FlashBazbo
Jul 2, 18 10:50
Post #8 of 10 (1374 views)
I didn't mean to offend you. I honestly appreciate all your input and responses.

I was hoping to either debunk or gain confidence in my "new" LTHR number. Having worked back through my TT files, I debunked my "new" number and now have confidence in my "new, new" number. Hopefully, I will keep this one for another 8 to 10 years.
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Re: When is your LTHR not your LTHR? When, why, who changed the LTHR Calculation? [FlashBazbo] [ In reply to ]
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jaretj
Jul 2, 18 17:26
Post #9 of 10 (1296 views)
No worries, argue was the wrong word, discuss would be a better one.

The HR vs Power debate has gone on for quite some time here.
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Re: When is your LTHR not your LTHR? When, why, who changed the LTHR Calculation? [FlashBazbo] [ In reply to ]
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Rocky M
Jul 2, 18 18:00
Post #10 of 10 (1282 views)
So this doesn't happen again, write down the protocol used, calculation method, everything leading up to the test in detail (even caffiene intake), sleep, etc. Try to replicate using everything you logged in your TP account, so you are working apples to apples. Even equipment. A change in position can affect your output as well.
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