Heart Rate (HR) Threshold

I know heartrate threshhold is not as good as power to compare your maximum capability to. However, I’ve been doing TR since November. Before November I was fairly certain my LTHR was 169 beats or close to it. I based that on that “feeling” you get that causes you to look at your computer and you see the same heart rate over and over. That may not be a good way to gauge it, but all the time I thought it was 169 and that LTHR was nearly impossible to move AND that you could only sustain 2-5 minutes above LTHR. I just completed Mount Goode and spent over 15 minutes above 170 and probably 10 minutes straight at the end between 175 and 177.

Is my LTHR going up? or did I just underestimate it?

Heart rate is variable on a day to day basis, and you should expect it to vary some just because your heart has to care about every process going on in your body, and not simply the watts you’re outputting. Things like temperature and cooling, caffeine/medications, fighting off illness, fatigue, etc all impact what your heart does, even if you’re comparing to the exact same power outputs.

If you trend it over time, you can rely more on the trends, because the variability will average out. It’s much less useful for any one specific ride. If you want to rely on the trends, try to keep the rides/conditions you’re comparing similar, as that’ll give you fewer sources of error.

Also, as fitness and power profile changes over time, your may develop the ability to sustain an effort at a different percentage of your VO2max. That would also affect your ability to hold a different HR than previous.


As mentioned heart rate is susceptible to a lot of variation. However, as you become more fit your LTHR will actually increase and get closer to your maximum HR. This means that you’re able to ride at a higher wattage with a lower HR, that is a good thing.

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Interesting! Never knew it went up as you got stronger. Going to do some Googling on that…

You can read Joe Friel’s blogs from years back before power became the sole metric of work on a bike. We have become so infatuated with power as the sole metric, that we have lost sight of the value of HR info.

If my memory serves me correctly, here is a rough guideline for fitness based on heart rate (FTHR/Max HR) . . .
couch potato 80-85%
recreational exerciser 85-87%
amateur athlete 87-90%
elite athlete 90-92%
world class 92-95%

Similar to tracking FTP growth, you can track this ratio.
Note: there are debates on this as to whether you can increase your FTHR and HR Max (personally, I have accomplished both and am currently at 91%).

Another good Power/HR metric is known as decoupling factor. It uses the ratio of your average heart rate to normalized power during a segment/interval as compared to another similar segment to determine fitness improvement. You can read about it on Training Peaks. Joe is also the author:


Both TrainingPeaks and a Garmin will suggest threshold changes of HR and Power. While I’ll typically reject them, has anyone evaluated how accurate these may be for setting zones between FTP tests?

unless you did the 20 or 30 min LTHR Joe friel suggests its safe to assume you simply estimated too low. My LTHR went up ~10% going to untrained to trained over the course of ~2months and has stayed pretty much the same for 3-4 years now despite huge changes in FTP depending on the time of year and training status. I attribute this increase mostly to learning how to suffer, which involves knowing how hard and how long you can actually push yourself at your limit

Anytime my LTHR goes up in training peaks, I use it. Currently it is at 187. I trust it and use that for races that are long or mtb stuff. Crits I don’t even look at it.
My max, I’m not sure, but have seen 208 a few times. I have it set at 200 I think.

Interestingly enough, my THR HR has not changed much at all since 2010, which was only my second year of racing. I still have some race reports on the internet I can reference and the HR averages are only a few beats lower now since my max has gone down slightly, like 3-5 beats.

I’ve noticed it is a lot harder for me to get to that level… when I wasn’t as fit, it was easy for my HR to spike up, now I’ve got to go REALLY hard to have it spike up quickly and my current HR response is more of a gradual change. It’s also knowing my abilities better and getting better at pacing, whereas 9 years ago it was more of a start fast and fade while I can do more steady efforts for a time trial or race. Starting fast and fading usually gets a higher HR average for me compared to pace since once my HR is high, it doesn’t take quite as hard of an effort to maintain it


My max HR that I’ve got indoors was 197 and that was last year or something. I recently did a race where I went at 181bpm for an hour. So 92% would be pretty correct for me at least. Usually when I ramp-test I’m up at 194-196bpm when I finish.

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I posted the info from Joe Friel in the thread below, but 90-92% would put you in the elite category; 92-95% world class. It’s highly likely that your stated FTHR is substantially above your actual FTHR. I’d suggest doing the 20min test and taking 95% of your average HR during it to get a more accurate FTHR.

This is incorrect and will produce the wrong value for a number of different reasons. The 20 minute test suffers too much from anaerobic energy contribution (since its actually a supra-threshold effort) and the 95% correction factor is too variable based on individual physiology and training state.

The truth is that finding your LTHR is challenging and it usually requires multiple data points to make a good assessment.

The following types of tests will get you close:

  • Take the average of the last 20 minutes of a longer steady state time trial (more than 30 minutes, 40 is better)
  • Highest 60 minute average heart rate from a steady hard race (RPE 9 or 10)
  • Ride at a well-established FTP until exhaustion. The second half will be close to your LTHR.

172bpm for 20 minutes = 93% of my max HR of 185.

I guess I’m world class. Someone needs to tell David Brailsford :stuck_out_tongue_winking_eye:

If you execute Dr. Coggan/Hunter Allen’s 20min FTP testing protocol you are eliminating/minimizing anaerobic contribution during the “warm-up”.
[See page 30 of the recently released 3rd edition of “Training and Racing with a Power Meter” by Coggan/Allen/McGregor]

The 20 minute Coggan/Hunter Allen FTP test is a power test, not an LTHR test. The 95% correction factor for HR doesn’t apply in that case.

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Just scanning your workout, clearly you can get anaerobic contribution to the effort you highlight. 172 is not your FTHR, at least as determined from this workout.

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The info I am providing (how to estimate your FTHR from the Coggan/Allen FTP test) came from Joe Friel.

The text you are referencing is specifically referencing power, not HR.

Friel’s LTHR protocol has always been last 20 minute average of a 30 minute all out time trial. He has revised his power protocol to recommend the 5+20 test, but I haven’t seen any recommendation anywhere for using 95% of the HR average from a 20 minute test.

It’s in friels latest training bible. It’s pretty close for me but I agree that the more anaerobic contribution you have the further off the number will be

Yeah, it’s a bit lower, in the mid-high 160s.

Separately, why is there an issue with some energy coming from anaerobic means? At lactate threshold, some of the energy produced comes from anaerobic breakdown of glycogen into lactate - so not sure presence of anaerobic contribution would necessarily mean I’m above lactate threshold (although in this instance I likely was).