What’s your real FTP?…AKA Fatigue Resistance

I’ve become increasingly interested in measuring performance in a fatigued state. Some people look at their power curve after some work, but we all know that KJ is an incomplete measure for this. We also know that fatigue resistance is the main diff between the pros and the under 23 folks.

Here’s some interesting research, with an specific protocol and raises the question on what is a good test for different people, more like us, trained, competitive cyclists.??

The Relationship between Physiological Characteristics and Durability in Male Professional Cyclists
Spragg, James1; Leo, Peter2; Swart, Jeroen1
Author Information
Medicine & Science in Sports & Exercise: August 12, 2022

Have a look at Xert MPA


Sadly, completely fails for efforts below TP

MPA doesn’t really account for fatigue for long excursions well

My Trainer FTP is 264. My outdoor FTP is 273. If you asked me what I could hold for an hour on a climb I’d say 255 maybe 260 max.

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You’re probably finishing at an elevation that is 1,000m above you’re trainer in that case, so I think all of your numbers are really close.

How about after 1-2 hours of mixed work including threshold and Supra threshold?

In theory wouldn’t it be the other way around considering my trainer FTP is lower? I’m assuming you’re taking altitude into account?

Personally I think it’s more to do with me being able to push more on a climb than a flat road. I don’t think I could hold 230w for an hour on a pan flat road.

Also my outdoor FTP wasn’t from a 20 min test. It was my best 20 min out of a 40 min hill climb race.

I am assuming that the average elevation of a 1 hour climb is greater than that of the other efforts. Efforts done at a higher elevation will result in a bit lower wattage. Adjusted to accommodate this, it puts your estimated climb number closer to your tested efforts.

I’m not sure what that entails exactly. It takes me about an hour to get to the base of any climb. I typically stick to ~180w (Z2) for the hour with a mix of Z1 on the descents and Z3/Z4 on the rolling hills.

Looking at a race from last year, I’d say the first 90 min would more closely match what you’re describing. In that instance it was followed with a total of 6000’ of climbing. On the five main climbs (varying from 1-7 miles). I averaged 236-237w which was my goal. I felt on the upper end of my comfort level. I definitely didn’t want to push any further. By the last climb I was really starting to feel it and I still had a 20 mile solo effort to go.

I don’t think this answers your question. To me, I use FTP to set training zones for intervals and for pacing in events. I ignore the rest of it.

Cool. I think it’s illustrative, call your FTP in the second part of the race 240 or whatever. So you would say your delta is ~12%. What some coaches are suggesting as the 4th dimension of fitness, is this delta, ostensibly you want to train in such a way that enables you to minimize that % differential.

Makes sense. I joined TR about 5 months ago with the intention of improving on the race mentioned above. It’s coming up next month. My goal is to hold 245-250 on those five climbs and still finish strong. Time will tell whether structured training and TR will get me there. Fingers crossed.

if you listen to San Millan, another difference that can be measured is blood lactate levels as discussed here and in some papers:

the “Lactate and Performance” section essentially concludes with a loose training recommendation on how to improve thru training - lots of endurance plus some high-intensity work. Do that over long time frames. That is one way of closing the gap between Joes and pros.

Another one I’ve got handy is the Coach Tim Cusick on the WKO5 webinar

Pretty much reinforcing the point of long steady endurance rides, and having a well developed FTP thru extensive work to push out your time to exhaustion (TTE). I’m a total recreational cyclist, but have pushed out my TTE to 65 minutes and that was the year I could hang with the A group on Wed worlds and had very high repeatability of 350-500W short pulls into headwinds and then dropping back and riding under threshold of about 270.

Stamina is a metric in WKO but you can easily estimate yourself from the power curve:

by taking notes of your power drop-offs from 1 hour to 2 hours to 3 hours as briefly mentioned in the 2 minute Stamina Defined video short: https://www.wko5.com/power-duration-science-explained

the coaching company I’m with is doing some work in this area, in collaboration with Dr Phil Skiba. If you haven’t seen it, this page is worth a quick look:

but it doesn’t have hard numbers, just illustrating the concept that your threshold drops over time and also dependent on fueling/hydration.


That’s loosely why I like riding up long climbs every few months. The one I use is about 20 miles long. Takes about an hour to get to the base. The point I start timing from is a bit further up the climb though. My FTP is 284 at the moment and I averaged 262 for the last 14 miles.

Admittedly not the same thing as doing a bunch of intervals and then testing, though.


I think that is practical, and aligns well with what coaches will have you do - “go out and do 1500kJ of endurance, and then do intervals” (replace 1500kJ with whatever).

The other practical one is extending time to exhaustion at your threshold power. And pushing up your power curve at 2 hours, 3 hours, 4 hours, etc.

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That certainly is a useful workout if you want to work on your fatigue resistance, but workout ≠ testing. And do we have to call everything FTP? After all, even riding at 60 % FTP becomes hard eventually (think an Everesting attempt or a 600 km ride).

(I’ve done a few workouts like those this year, and they are pretty fun.)

Or anyone else who doesn’t have the time pros and young people have. It is easy to say “ride 1,500–2,000 kJ” at endurance pace and then start your workout.

Yes, this is key. The power curves should be something like Aerotune’s, conditional on carb intake rate.

It’s seems that the precise protocol should be tailored to the athlete level. The OP protocol wouldn’t cause enough fatigue to WT level riders

I always wondered what exactly this “steady pace” is? Like, ride 3-6 hours while spinning very lightly, without ever allowing your pulse to exceed certain mark? Or are you still allowed to do some quick power sprints, some fun descends that lasts a few minutes with all power you’ve got , some dynamic steep slope climbing while standing etc? I mean, as long as your average heart rate stays at 120-125 bpm.

Because otherwise that results in a quite dull, unremarkable hours of monotone spinning on a bike. I just never was able to maintain such pace for hours, it’s too boring for me.

Very unscientific numbers but:
AI FTP has detected between 274w and 286w for me but I suspect it is polluted by the data I feed it which contains a lot of out door group riding upright on the road bike so I am currently training for TT’s of a FTP of 260w. Which on my current form I still feel is a little high for outdoors but it feels right on the trainer. This season though I’ve not done much more than 232w over an hours TT. (Edit I dropped it to 250w on the 12th and forgot).
I guess I can count the 2nd hour of a 2 hour TT as fatigued; in my last two (and only) 50miles TT that was 213/4w.
Motivated and no surges I reckon over a longer period I could do 190-200w, although my ‘get me home’ pace when I have had surges which have blown me is less than 150w :joy: