FTP Field Test complete explosion on 5 minute blowout

Have been using AI FTP detection for awhile and not doing any field testing at all– FWIW it seems to be pretty accurate, but being a numbers guy and also (maybe) a masochist, I decided to do a 20 min FTP test, specifically I wanted to get the Wahoo SYSTM 4DP full frontal protocol a try.

During the 5 minute maximal effort I went completely to the well– it is supposed to be “all out,” after all, right? During the 5 min effort, I started slightly conservatively and ramped up progressively, probably starting in the ~360-380W range and the last couple of minutes in the 400-415W range. Towards the end I was really seeing red and cross eyed. The full frontal has 5 min of easy spinning/getting off the bike before the 20 min effort but I was so gassed that I basically could only crawl off the bike and lay on the floor. My heart rate stayed persistently high and by the end of the rest period + a little bit more I was in no condition to start a 20min all out effort. Decided to pull the plug and spin out for a few minutes at ~100W which would generally help bring my HR down into he 11X-12X range, but it stayed at ~140-150 for quite awhile. I spun for 10-15 more minutes until it came below 130 and hopped off.

Has anyone ever experienced anything like this? I am super unclear on what could have happened. Is the 5 min effort not truly supposed to be 100% all out as hard as possible? Does the protocol assume that most will not be able to actually push 100% of what they are physically possible to the point of near passing out?
FWIW I was happy with my 5 min result, just confused as I thought I was following the protocol well but ultimately could not finish the test (failing a workout is quite uncommon for me.)

  • context, I was sick for a few weeks in late April/early May, but I am not sure if that would really contribute to such an experience. Any ideas what happened or similar experiences? Thanks!

It’s been awhile since I’ve done one but the 4dp test is hard; in particular the 1 minute test at the end feels a bit like a kick in the shin at that point. They want the 5 minute (and 1 minute, and sprint) effort to be as hard as possible to fit a curve. As a result I believe they’re de-rating the result of the 20 minute test less than the typical 95% (iirc, they say this in the workout test).

The primary purpose of the blowout effort in the 95% of 20 minute test is to deplete the anaerobic system which would require riding very hard; though at least I’ve never ridden it quite as hard as you’re describing.

Being sick for a few weeks recently could affect you, too. There’s a difference between recovering enough for general life vs recovering enough for a maximal test

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I did something like this once. Got an all time 5min power by like 15 watts and then only made it 10min into the 20min (at what should have been a completely reasonable power) before I just collapsed.

I have no other insight other than yeah it’s happened to me too.


I’ve done the Hunter Allen 20 min test and the Friel 8 min test on back up back days and gotten an “FTP” that was within 1W of each other. Ramp test was pretty close too. However, none matched my true FTP because the sport tests are all heavily influenced by your anaerobic to aerobic fitness ratio.

The best way to know your power curve is to do separate maximal efforts at several durations, such as 10sec, 1m, 5m and near FTP. Forget the 4DP test. Use a real FTP test, like the Kolie Moore protocol or do a long, steady hard ride and use your power curve

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Well, thanks all. I guess I will be staying away from the 4DP full protocol in the future then. @huges84 thanks for the suggestion to keep the different areas of power curve in separate protocols.

Glad to know it is not just me who has had difficulty with this specific test. Maybe the sickness after effects played a role and maybe the protocol just isn’t the best.

I’ve blown up on 20 minute tests, but not because of a 5-min effort. I haven’t done the Allen protocol, and am not interested in the 4DP test.

The last time I blew up was 3 years ago on the INSCYD test protocol. That one is basically a critical power test, it has you doing:

  • 15 second seated sprint (all-out)
  • as much recovery as you need
  • 4-min “hard start, all-out, DO NOT PACE” effort
  • as much recovery as you need
  • 20-min “hard start, all-out, DO NOT PACE” effort

I took 34 minutes between the 4-min and 20-min, but my legs were pretty much dead. My hard start was weak and I held on at 237W. They asked me to redo the 20-min only, and the next one was 252W.

For the 4DP test, there is a good writeup on the Wahoo site.

The way I have read these tests and from what I heard from them is that you are not trying to set a five min power PR. Doing that would totally crush you. Heck, the last five min all-out effort I did left me on the side of the road gasping for like 10+ minutes.

I do five min at 100% of FTP, short rest, and then into the 20 minutes. 95% of your 20 min number is “your FTP.” Another solid test is just warmup how you want and do a 30 min TT by yourself and call that your FTP (Friel method).

That’s not the protocol though. It is a 5-min max effort for a reason.

I am a former runner who still coaches so I tend to think of thing like this in the Track & Field realm. Who in their right mind would go try to run a world record at 1500 (only a 3:30 race) then 5 minutes later try to do a world record in the 5k (only a 12:30 race). Absolutely no one.

Just my opinion but an all out 5 min test… truly done ALL OUT… should wreck you and take hours to recover from. Maybe that’s the point? See what mediocre effort you can give after ripping your legs off?

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Coming from a running background this resonates! I did spend probably 15-20min lying on the floor feeling like I was dying after the 5 mins so I would hazard a guess that I was near about full max for that day. I also wouldn’t really ever think to double back after a full gas 1500m with 5-10min recovery. It would have to be an hour+ before considering an all out effort again and I would still assume reduced performance.

It makes me wonder about the protocol though… is 5 min “all out” assuming that most won’t actually go full 5 min all time record? When I see “maximal effort” I assume it means truly maximal.

Either way, I am thinking that next time around I may try one of the the Kollie Moore baseline TTE tests as described here The Physiology of FTP and New FTP Test Protocols which at least intuitively to me seems to make more sense– as your FTP time to exhaustion increases you can make your way up the progression… so you can see improvement both in your “threshold” watts and in the time you can sustain those watts.

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KM test for the win. Even if you start too low, you can just ride the test for a bit longer.

I had a similar experience with VO2max intervals. My first session out, I made 3x3minutes. Two days later I did 2x3min and I had no gas for the 3rd interval. After those two sessions, my legs were wrecked for days. I suspect that part of it is being 56 years old as well as not doing max efforts like this very frequently.


Weird, the conversation I had with one of the two who laid out the test clarified that it shouldn’t be trying to set a 5 minute PR but you probably know more than I do.

The logic of setting a 5 min PR followed by 10 min at 65% into 20 min all out does not seem ideal and that’s the messaging I got. Cycling has had many things proven to be ineffective over time. But then again, some people wear knee warmers anytime it’s cooler than 70, only ride in the small ring during the spring, and don’t enjoy ac in the summer.

Personally, I prefer Friel’s 30 min test but they’ve been about spot on with how I do the 20.

I’ve done them at something like 120% of FTP for the first couple minutes and then adjusting up/dn slightly based off RPE so it’s relatively controlled (ie, not peak and fade) but still hard. Similar to others, if I did a 4k pursuit than I’m probably won’t do anything other than lay in the grass for 5-10 minutes following the race.

My memory of the 4dp test is 1. Ow and 2. I still hadn’t recovered by the time I started the 20 minute portion, though the 20 minute test did go better than I would’ve thought at the beginning. Unlike the traditional 20 minute test, it is actually using the 5 minute data, though.

It’s Hunter Allen’s test. I have no idea who the “second person” is. I don’t care either way as I don’t use it, but I believe your interpretation of the 5min as 5 min at FTP is what’s off and is really going to skew results high in a lot of cases. 5 min at FTP shouldn’t cause any fatigue whatsoever, so it’s just like taking 95% of a 20min MMP test which is almost always going to be too high.

But I have never read anything that says anything other than a 5min max effort. I don’t care about the semantics of it being a power PR or not. The intent is pretty clear to me.

The 30 min threshold effort is better. Longer even better than that. Not sure what the Friel test is for power, I’m only familiar with his 30min threshold HR tests, and have never used that protocol to set an FTP. YMMV.

You’re trying to estimate the power you can sustain in a quasi steady state for about an hour by riding for 20 min, so yeah, you probably do need to go into it with some level of fatigue. 10 min of recovery and a decently fit person should be able to do another hard effort.

This is how I started testing in 2016. Go out by yourself and do a 30-minute time trial. Do it as if you were full on racing for 30 minutes. Sorta like a Empirical Cycling / Kolie Moore test protocol 3 except its 30 minutes. My advice is don’t get hung up on 30 minutes, I’ve done them for 30 minutes, 35 minutes, 28 minutes, 51 minutes, 32 minutes, …

“the average power for the entire 30 minutes is an approximation of your FTPw”

“As with LTHR testing, the more times you do this test the more accurate the results will become since there is a learning curve associated with such an effort.”

May 2012 article: Joe Friel's Quick Guide to Setting Zones | TrainingPeaks


Yea I was doing those before I had power to get my LTHR, I wonder how stochastic my efforts actually were back then

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First successful long effort on December 11, 2016 on my Winery to River segment (completely flat except for 2 small levies)

shading in brown is 95-105% FTP.

More stochastic than my current efforts, but variability index is fairly low at 1.019

My personally estimated FTP at the time was 249W. WKO has modeled FTP at 251W. Intervals estimate for that ride (just that ride) is 242W.

For a newb I’d claim I rode close enough to threshold, and 47+ minutes.

Compare that to a recent 20-min TT pacing effort on rollers:

LOL big difference, my legs can do erg mode now, at least on gentle rollers. Had to slow/stop for left turn onto county highway, and then a 4-way stop.

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Yup, and the OP has identified one of the limitations with it… just how hard are you supposed to go during the 5 min “blowout” effort?

That said, as I have always emphasized, I am not a coach, much less one who has to deal with clients remotely. As well, although it isn’t the most precise approach, on average taking 95% (vs., say, 93%, or 97%) of 20 min power seems accurate (just not sufficiently precise, at least IMHO). However, it isn’t the definition of FTP, which is what almost every scientific article on the subject gets wrong.


You might ask yourself this: does it matter?

If you think about it, almost all exercise is intermittent… your muscles contract, then relax, then contract again. The question then becomes, what is the time scale upon which such cyclic variations occur, and how does that impact the underlying physiology?

Approached from that perspective, you quickly realize that short-term fluctuations in power output are largely (albeit not entirely) irrelevant.

TL,DR: forget about trying to hold your power absolutely constant - it doesn’t matter.