Measuring/Estimating TTE (Time To Exhaustion)

So measuring TTE seems fairly obvious: take your power at FTP and see how long you can hold it. In general, expect anywhere from 40-59:59 mins. Is there anything more to it than that? How do you determine “holding it”? A power drop of some sort?

Hypothetically, if I want to “spitball it” because I might not want to measure it in the way I just described, any rules of thumb or guidelines? I realize one answer is “TTE is a metric that WKO4 models for you, so you don’t have to this or that…etc.”, so if the answer is “just use WKO4 or Golden Cheetah”, fine. But we get at FTP (more or less) without needing the software to model it for us, can we do the same with fatigue resistance?


(edit: yes, i’ve read the TP articles and seen Tim Cusick’s video presentation)

Generally, I just do the progression tests where you start slightly under FTP and then ride until exhaustion. TTE=length of the test, FTP= average from the total test.

WKO will bounce the TTE around based on data points coming in or out of the PD curve, but for the most part I just look at longer efforts to determine it.

Trend and curve shift is more important than the absolute data points if you catch my drift. Easy way to do this in TR is to setup two equivalent Base seasons, turn on Season Match and look at the power curve. If the curve is shifting up and right, you are headed in the right direction.

If you want to eyeball TTE, look for the inflection point on your power curve. It should be pretty easy to spot if you have some maximal efforts in the 35-60min range.


Totally agree. Very helpful answer, so thanks @stevemz. I’m heading up and to the right compared to some previous timeframes (using SeasonMatch etc).

What I’m trying to do right now is base some sub-threshold (tempo, SS, and even Threshold) interval lengths off of TTE rather than A) just doing what TR says (not that that’s bad, just think I can get more individualized and extend them more…target intensities are fine), or B) using my intuition.

Sounds like what I need to do is do at least an initial progression test. From that point I should just be able to progress them by using recent efforts. I do a similar thing with FTP. I don’t do the ramp test too often (even though it’s fine and fairly non-invasive). I can usually adjust my FTP based on recently workouts (Lamarck, etc).

If you have WKO4, just look at the Extensice FTP recommendation in Optimized Intervals.

If you don’t, the usual recommendation it gives me is around 94% of mFTP @ TTE length. If you can’t do it all in one go, just break it up into a long and a short or short and long.

What I’ll usually do is to take the TR workouts and modify them, especially if they are longer. If it has 60 minutes of SS TiZ, I might break it up into 2 intervals of 35 and 25 minutes, or 40 and 20. This is especially helpful if your TTE is on the lower side (35-45 mins).

Yep, that’s the plan.


@stevemz Will DM my WKO4 question.

I’ll take this to DM.

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i want to do next week this test.
i thought to start with the baseline test :man_shrugging:t3:

Empirical Cycling FTP Tests


    • 10 minutes at 92-95 percent of target FTP
    • Increase to 100 percent of target FTP for 15 minutes
  • 10-15 minutes gradual power increase until exhaustion

My TrainerRoad indoor FTP is 311 (outdoor i feel like to be able few watts more).
The WKO5 trail version estimate my FTP around 325, but i did not pushed a all-out effort the last weeks so far.

My Question:
Should i take something between as my target FTP 317 :man_shrugging:t3:.
starting with 92-95% for 10‘ :white_check_mark:
go for 15 minutes with my target FTP :white_check_mark:
than i try to gradual power increase until exhaustion 10-15min. :man_shrugging:t3:correct?

Can you show us you test and the WKO Result after your test?
maybe i get a better picture if i see your graph.

thank you!!!

Read all about it:

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if you cut away all jargon, then you can ride to the point when either your energy is depleted, your power is depleted or your motivation is depleted. Can you predict those? Yes, although you can over complicate things, and ignoring environmental conditions then you can estimate your power at any duration from power at any known duration or time at any future power (, you can do the same with energy ( Motivation is however very hard to predict and model!

Sorry to drag up an old thread @stevemz, but i am getting my head around creating Extensive Aerobic intervals from my WKO PD curve, and this thread was helpful, but raised a question

If you use the Optimized Intervals recommendation of say 97% of PD at TTE, at what point does the PDcurve get pushed out by performing by holding 100% of current TTE for longer?

Is the normalized residuals long target often past TTE to achieve this?

DM if preferred

This is going to sound obvious, but extending TTE…increases TTE. If you hold mFTP for longer than the current TTE, it is going to readjust. That being said, the Extensive intervals are more likely to affect Stamina (as a number) in my experience.

The long target totally depends on your individual curve, but generally speaking, if you have a short TTE, it is going to be longer and if you have a long TTE, it’s going to be shorter.

My current TTE is 1:04 and my long target is 45 minutes (since I think my mFTP is a touch low based on the 90 minute effort that WKO calculated it off it)

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And your TTE also changes when you add short power efforts to your curve (of course we are talking only about WKO pdc). Usually when I target my short efforts (below 5 min) and the curv goes up, my TTE shortens along with stamina. So then you have to add these longer efforts to show that you are capable of doing them.

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That was what I thought, so I was confused re how TTE could in fact be extended if I was doing intervals at a % reduction of the PD curve at or near TTE. I suppose in time as the durations of TIZ in intervals extend well beyond TTE, the average power will end up higher than than the PDC at that point given the accelerated drop off in the PDC.

Thanks for your help, much appreciated

Yeah in general TTE is one of the more sensitive metrics when I track it, but if you are working through a sweetspot progression to longer intervals, you’ll see it slowly creep out, primarily from increases in the part of the curve from 1-2 hours.

(This purely based on my own observation of how the numbers change, rather than any sort of training prescription just FYI)

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I just did the baseline testing of 5, 20, 1 minutes and sprint. FRC and mFTP both moved up a reasonable amount, and as you said TTE reduced back to a paltry 33 mins, hence the initial focus being on extending that out to a useful number

Reinforcing what has been said, and it should be obvious now, WKO isn’t going to predict your TTE. Rather it is just giving a number based on the (90-day) PDC. Don’t feed really short power max efforts for 90-days and your TTE will increase as the model decays at the left side of the power curve. For example I recently had some hard 1-5 second efforts fall outside the 90-day window:

and when those stronger <5-sec efforts fell outside 90-day window my TTE increased.

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Can TTE even be measured accurately?

Based on the research, I have no idea :man_shrugging:

Speculating: I’d imagine the estimation variability is lower for cyclists than it is for runners, given we have much more accurate power/effort measurement devices.

In terms of my own experience, there are some reasonable brackets that I can draw around my ability to hold my FTP within specific ranges based on state of training and stamina.

Is there really a substantial performance difference between 35 and 40 minutes TTE? Not really, even though it’s 14%. The training prescription is probably going to be very similar.

Is there a substantial difference between 35-40 and 55-60 minutes from a performance and training prescription standpoint? In my experience as an athlete, yes, the workouts and progression are different.

Personal opinion: TTE doesn’t need to be super precise to be useful.

This. So basically 35-45 is little different than 55-60 TTE to give your body proper stimulus. With 60 min tte doing 40 minutes TiZ threshold can be not sufficent. But I do not know what is other application TTE can have (other than measure of your overall fitness)

What does the accuracy of the power measurement have to do with it? Isn’t all that matters is that the demand (running speed or power) is held constant?