Threshold heart rate increase with FTP

Hi all,

Been using TR for about 7 weeks now working through SSBMV 1&2 - enjoying my first experience of structured training. Since increasing my FTP I notice that my HR during SS intervals and threshold is now noticeably higher than what I’d typically understood to be my HR zones. Does threshold heart rate typically increase with FTP like this? I had expected HR zones to remain stable and the adjustment to be an ability to put out increased power at the same level of cardio work…Is there a typical upper limit to this LTHR increase and could I expect my max HR - which is pretty low - to increase too? (some context and additional info to follow)

Of course HR varies day to day but I’m talking multiple SS sessions where my HR sits at 153-157bpm which I’d established as threshold, and threshold intervals where it’s 158-160 which is typically my supra-threshold/VO2 max territory. I’m not getting the lactic burn in my legs that would typically be associated with above threshold work, so it appears to be some physiological adjustment rather than a bad test.

Of course a slightly too high FTP could be part of the equation - my FTP started at 341 and at the end of SSB1 had increased to 361w which may be marginally high since I’ve got a decent anaerobic contribution which helps on the ramp test. However, I’ve been able to complete all SS and threshold intervals since the increase without excessive discomfort so logically it’s not that far off.

Before getting a turbo I did all my riding outdoors and with only HR to go by so as a result have (or had) a really good handle on my zones, perceived exertion, etc… Through SSB my HR numbers were exactly within those established HR ranges excluding days with excessive fatigue/caffeine etc. For reference my resting HR is roughly 44 and max is 178 at a push.

There’s some discussion tangential to this in the below thread although I didn’t find it answered my question directly. (Heart Rate (HR) Threshold).

Appreciate your help


Your real maximum can’t increase but it is common for folk to assume a maximum which is lower than the real value :+1:

I have found that the first week of the new FTP, my heart rate is elevated for the zones but by the following week it settles into where it should be. I chalk this up to pushing demands of my body and coming off a rest week in which I didn’t hit those bpm marks.

I’d say of it continues to drift upward you may want to look at other things going on like nutrition, breathing and just regular body health.

I also have well established HR zones and with rare exceptions they work both inside and outside. Without knowing your trainer environment and outside temps, my first hunch would be ramp test over-estimating FTP.

I’ve seen my threshold HR increase in TP 4 bpm since I started to use the 20 min FTP test about a year ago but I don’t know if it’s really increased as a result of training. I have no idea whether it can be raised, in my case I think I just got used to “going deep” during the test and it happened to raise a little. It started at 174 bpm after the first 20 minute test, went to 175 after a 1 x 90 SS interval I did at the end of a 4 hour workout about 2 months ago, then up to 178 in a 20 min test a few weeks ago. This last test was better paced than the first one and I think I did a better job getting the most out of myself that day, perhaps it has been 178 the whole time. The highest I’ve seen for a threshold HR in a TR workout was 172, couldn’t name the workout unfortunately.

You write that you use SS to determine your threshold, is that correct? Are we talking 3 x 10 SS interval or 1 x 90, maybe something else? It takes a lot to get my HR that high outside of a sprint, something like the long interval I mentioned above in a bigger workout or a hard 15+ minute interval.

FWIW you should really do a proper long all-out test to determine lactate threshold HR (LTHR) and the use LTHR to calculate HR zones.


Agreed, I don’t think there’s anything in the SSB MV plans this athlete has done that could determine their threshold HR so I asked.

I could’ve put threshold in quotes. I’m going off what TP tells me to use as it.

I’m going off this:

And the fact it’s first time training on a turbo.

First guesses without more info:

  • ramp overestimated FTP
  • no fans inside and it’s warm inside and outside training in cooler temps

I have modest fans and garage is 80F in summer, and 90F training outside. Except for the first couple weeks of hot temps, my HR is similar on inside vs outside workouts.

Thanks for the responses so far. I have a couple of fans in use, not the most powerful on their own but in combination and with the door open in the British autumn/winter time I haven’t found any issues with overheating.

As Bbarrera states i’m taking my LTHR from previous experience rather than TR workouts, and am quite confident about the zones. What I understood to be my ‘SS HR’ was spot on coming into SSB1 and same for threshold which I encountered with a few of the over/under workouts.

It may be that the ramp test has slightly over-estimated my FTP based on what you guys are saying, but it just seems strange than when doing some 10-12 minute 99% FTP intervals I didn’t experience any real leg burn that I’d expect from riding above FTP. The burn I mean is the type typically experienced when doing the over part of over/unders. So effectively the perceived exertion feels about right, it’s just the corresponding heart rate is higher…

I’ll keep an eye on it and report back in case of any changes. I remember on SSB1 I found the SS intervals much harder at the start of the block than by the end when I felt better adapted to the work so it may be that this is a by-product of adjusting to the new higher workload and may settle down in the coming weeks.



First lot of over/unders during SSVMV2 this morning with carpathian peaks +2. Very very tough but managed to complete it. Heart rate was way up but due to the nature of over/unders and trying to recover in ~1min at near FTP I suppose that’s understandable. I was able to feel the burn easing as the intervals dipped below back towards the 345w valley which is encouraging.

Easy answer would be do a 20 min test or even an hour test but realistically I’d rather just keep doing intervals and make gains. I’m not too worried about true FTP as I don’t need to put out any well paced hour max efforts. I would almost certainly fail to put out 363w for a whole hour uninterrupted right now, though I think this says more about my lack of training for sustained efforts being new to this whole thing.

I’ll see if my HR at ramp-based FTP power continues to settle down, otherwise maybe I had a low estimate of my LTHR. Failing both of those maybe it has increased from 154 to the high 150s

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QUESTION I HAVE BEEN CONSIDERING - - We all know that Power (FTP) and HR monitoring should go hand-in-hand. What I have also found since using structured training year round since JAN '17, is that during the training blocks, I get fatigued and using only FTP for training zones only makes me more fatigued. WHAT IF I used FTP for the first half of base phase and then use my HR zones for the second half of base? Obviously, I cannot fully ignore my FTP zones, but by focusing on HR zones, I seem to avoid deep fatigue for longer, if not all together. THOUGHTS?

Do we?

Similar here, as I get fatigued my HR will be a bit out of whack with the power (higher than expected for a given zone) which is clearly a result of fatigue. At that stage each workout of a given TSS actually provides a greater level of stress which accumulates and makes the issue worse… But then I think as long as I can manage to complete the workouts then that’s part of the process - perhaps lowering power to work from HR zones negates much of the training benefit. I’m not capable of answering that unfortunately though.