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20-Minute vs 8-Minute FTP Test

The goal of assessment, regardless of test protocol, is to get a snapshot of your current level of fitness. And since your power levels are going to be based on your assessment outcome, we want an assessment that’s as close to accurate as possible. As a result, we recommend using whichever test format gives you the best representation of your current sustainable power.

Whether you use our 20-minute Maximal Lactate Steady State (MLSS) interval or a set of 8-minute Power at VO2max (pVO2max) efforts, it's best to choose a format that you will stick with and one that fairly represents your fitness at the time.

Each test has its own pros & cons and I’ll elaborate on each of them briefly in order to help you choose a format which best suits you, both in terms of your current capabilities & capacity for suffering.

There's also a good explanation of the different ways to generate your FTP here at Alex's Cycle Blog. It's worth a read.


20 Minute Test

The 20-minute test is the preferred format for newer riders primarily because new riders simply don’t have an established feel for riding well above FTP — which is what’s necessary during the short, pVO2max efforts necessary for the 8 Minute Test.

It’s also an ideal format to break into shorter, more manageable segments. By breaking the 20-minute effort into four 5-minute segments, riders can subtly tweak their effort every so often based on longer periods of muscular feedback, i.e. a rider can slightly reduce their pace every 5 minutes based on perceived exertion or how their body feels.

The downside is simply that it’s a relatively long effort and pacing is an issue for less experienced riders.

Additionally, many riders play it safe during the longer formats and end up finishing with too much gas left in the tank. Evidence of this is illustrated via a 2 or 3-minute surge in power at the end of an effort that would ideally be evenly-paced over the entire 20 minutes.

As a result, their FTP and relative power levels are likely to be underestimated a bit (or a lot) rendering all subsequent FTP-based workouts less productive than they would be otherwise.

 

 


8 Minute Test

Our preferred format for more experienced riders is the 8-minute protocol comprised of two 8-minute efforts. This format yields a greater amount of information by demonstrating power at VO2max via each 8-minute interval, sustainable power/FTP once the best 8-minute power is reduced by 10%, and you can even track improvements in your aerobic fitness when comparing the 2 efforts afterward, i.e. a substantial difference could indicate a limited ability to recover & insufficient aerobic capabilities.

Past the initial assessment, riders can also observe changes in FTP, and arguably as important, compare power at peak aerobic uptake/VO2max from assessment to assessment, information that can be of particular value to competitive riders and exercise science geeks.

 


Assessment Specificity

A final consideration, whether an inexperienced or experienced rider, is the matter of keeping your assessment format specific to the type of rider you are. For instance, improvement in pVO2max usually isn't as important for an Ironman competitor or 40km time trialist as it is for a cyclocross racer or a criterium specialist.

This specificity is especially important when considering how assessment efforts are often themselves the day's workout, so why not work out in a manner that suits your training needs?


Summary

So our overall recommendation is to choose the assessment format that furnishes you with information specific to your personal goals and capabilities, a format which best mimics the demands of your events, and a format that ideally suits your strengths.

And try to recognize that assessment has its own learning curve and often takes a bit of practice. So while your early assessments might not yield the most accurate measure of your fitness, as you grow your fitness you'll also hone your ability to fairly assess it.

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Comments

  • Avatar
    Scott Alber

    Is there a reason to not do both tests?

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    Arthur Chase Lomibao

    At what phase of training do you recommend these tests be done? I'm approaching peak phase and I'm guessing now is not the time to do this

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    Matthew Taylor

    Arthur in theory you should do a test at the beginning to get your baseline. My personal coach has me doing a follow up test at 6 week intervals to check so he can adjust up or down my training plan.
    Scott there is no reason to do both tests. As results will probably be different. My advice is to find the one you like best and use it to get best consistency.

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    Chris Quinn

    So for the 2 - 8 minute TT's you go as hard as you can sustain for 8 minutes?

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    Chad Timmerman

    Sorry, Everyone. I had an old email address associated with these posts and it is no longer forwarding to my new email. All's well and I'll stay more on top of these replies. Here goes...

    Scott: Not really. I recommend using whichever format helps you yield the highest output and therefore gives the best representation of your sustainable power, and these both give you basically the same thing in that respect, an FTP estimate.

    If you want a fuller picture of your fitness though, the 20-Minute is arguably the better option in that you can kill that 5-minute effort prior to the 20-minute effort and get a good measure of your power at peak aerobic uptake/VO2 max. Then when you hit the 20-minute jobber, you'll have burned off a bit of your anaerobic contribution and get a fairer representation of your actual sustainable power.

    But those details aside, this format will give you a measure of your "aerobic roof" (5-minute) and your FTP/"aerobic ceiling" (20-minute) allowing you to then track not only improvements in both but also how they relate.

    For example, riders who can sustain upwards of 85% of their 5-minute power for an hour, i.e. their FTP is 85% (or higher) of their peak aerobic power might choose to target their VO2max while riders under 85% are better off chasing improvements in FTP and the duration they can sustain it with minimal fading.

    To further the metaphor, once your aerobic ceiling/FTP is close to your aerobic roof/VO2max power, it's time to raise your roof via VO2max work. But if your ceiling is a ways from your roof, work on raising your ceiling via muscle endurance efforts.

    Short answer: Both formats assess FTP but the 20-Minute Test can help you assess pVO2max as well as FTP so it's my preferred format when it comes to developing a greater understanding of your capabilities & limitations.

  • Avatar
    Chad Timmerman

    Arthur: We recommend about every 6 weeks but it's certainly phase-dependent. In your case, assessing fitness during a peak isn't nearly as vital or useful as it would be during earlier phases of training, e.g. base, build.

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    Chad Timmerman

    Chris: Yes. The merits of the 8-minute protocol is that you have a couple cracks at your best 8-minute power (which, incidentally, can give you some insight into your power at VO2max as well as power at Functional Threshold) but also an opportunity to see how well you recover between efforts.

    Riders with greater endurance, greater aerobic capabilities will bounce back and quite often have 2 really consistent & comparable efforts while less fit riders will typically nosedive in that second effort having given all they really have in the first. So the comparison of these two efforts can be telling from assessment to assessment.

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    Bill Coffee

    Chad - just so I'm clear, when doing the 8-minute test, I want to ride at my hardest, sustainable effort for 8 minutes. That may or may not be above the FTP graphic on the screen?

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    Darden Mueller

    Bill: You will want to put all of your effort into the two 8-minute intervals. An FTP test represents the power (measured in watts) that you could theoretically maintain for about an hour, and it's the single metric we use to scale each of your workouts in our shared quest to keep your fitness growing. The graphics above displays the 20 & 8 minute FTP tests.

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    Travis Glover

    Curious thing I just noticed after my last assessment...in which I phoned it in on the 2nd 8 min. Should the app be averaging the two 8 minute tries to recommend a new ftp? It is. My ftp based on my first effort is exactly the same as my last assessment. See https://www.trainerroad.com/cycling/rides/2812293-8-Minute-Test

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    Travis Glover

    ...but the recommendation is 90% of the average of the two 8min

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    Fragkiskos Papadopoulos
    Hello coach, does the selection of the testing protocol take under consideration each riders advantages? For example should a steady-state rider select the 20 mins. protocol rather than in the 8 min. VO2Max efforts that a short-power athlete can sustain better?
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    simon watson

    I just completed the 20min FTP test and got an FTP of 158 which feels artificially low. I'm using a cyclops fluid 2 - do I have something wrong with my set up?

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    Darden Mueller

    Simon: Will you send us an email to support@trainerroad.com, we can help ya out from there. :)

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    Matthew Taylor

    Simon Watson, you need to provide more information. Were you using a power meter? Were you using virtual power from trainer road software. Do you have another 20 minute test that would refute this being a low test? Have you ever tested before and what were the conditions and results?

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    John Tramell

    I have a question about a rather large difference between my 8min test and 20 min test. My first ride with trainerroad and a wahoo kickr in ERG mode with Garmin Vector pedals, I did the 8 min test. Im 44 years old and 6'3", 215# (97kg) The results for this first ride were FTP of 307. After several more rides I tried the 20 min test and got a disappointing FTP of 264. Same weight huge drop in numbers. I'm in the Half distance Tri (mid) base and build for a upcoming 70.3 in May. I know for a fact that I went out way to hard in the early part and faded at the end. So this adjusted my FTP and all the following workouts. But all the workouts since that adjustment seem to be quite easy and I find myself having to increase the intensity on the rides. I did another 20 min test today with no change in the FTP. I know that I had a few times where I did a quick back pedal to flush the legs but I thought I did better today then the 1st min test. I know I can hold 350 watts for the 8 min test but seem to fade after that. My question is what can I do to improve my 20 min test to more closely mimic my 8 min numbers?

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    Jeff Martin

    How important is it to have a HR monitor and cadence sensor when performing the test? I'm using a Tacx vortex which calculates cadence (how accurately who knows)

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    Anders Svendsen

    Simon: I trained whole winter with virtual power with FTP of 185, and when i invested in a power meter late january i got a FTP of 280. It may be a little demotivational to train to low wattage, but the zones will still be correct as long as you give it your all in the test.

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    Michael Gonzales

    Dumb question to which I'm sure there is an overtly obvious answer... what gear do you use in workouts and the test while using virtual power? I'm sure it matters, but I haven't been able to find this answer anywhere on the site?

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