I know it’s tough. I know the burning in your legs feels endless. I know 20 minutes is a long time. I’ve been through the 20 minute FTP test multiple times myself. Throughout my racing career I almost always used the 20-minute test to assess performance.
So I experienced first hand how hard it is. And that’s why I can unquestionably understand you were looking for shorter alternatives like an 8-minute or 10-minute test.
It might not be physically easier than a longer test but the mental side is a whole different world. A 20-minute test feels so hard to some that when I prescribed it to my athletes, some were in deep pain already before the test week had even arrived. But give them a shorter test and they won’t put comparable thought to it.
But despite the feasibility of shorter FTP tests, I argue that short tests like 8 or 10 minutes are a bad idea in general.
Let me explain…
A Problem of The Protocol
The initial problem that comes up with short FTP tests is the fact that power-duration doesn’t follow a linear relationship. Instead, power-duration follows more of a hyperbolic relationship above a certain threshold as shown in the graph below:
Essentially, the shorter the effort the more power you can produce. With more power I mean a lot more. For some riders their 2 minute and 10 minute power can deviate significantly already. What most athletes forget, though, is that power above a certain threshold isn’t only generated anaerobically but both a function of anaerobic capacity and VO2max among others.
So cyclists with a high VO2max and high anaerobic capacity can excel in those short FTP tests but may blow up in a 20 minute test.
Now, given the facts about the power-duration relationship, taking 10% off of an 8 or 10 minute test will overestimate a cyclist’s FTP in almost all cases. In fact, a study by Ineos coach Dajo Sanders and colleagues found that an FTP derived from the 8 minute test with a 10% correction significantly overestimated lab-tested lactate thresholds. While FTP from a 20 minute test might also be different than lab tested, it will be far closer than estimated from a short test.
The obvious problem? The shorter the test, the harder it gets to apply fixed corrections. But enough said, let’s look at an example from a former world-tour cyclist, where the mentioned plays out in the real world.
A World-Tour Example
As was common in the past and is still today the mentioned pro completed a series of all-out tests also known as power profiling.
I will focus on the 10 minute and 20 minute test result but leave you the 5 minute test result as a reference as well. The results are quite surprising. While the pro managed to hold 495 watts for 10 minutes, he was only able to maintain 453 watts for 20 minutes. That’s a drop-off of over 40 watts. Let’s do the math real quick. I take 10% off of the 10 minute power, although 10% is used for the 8 minute test. So even at a more conservative correction the 10 minute test would give him an FTP of 446 watts. In contrast, at 20 minutes his FTP sits at legit 430 watts.
Essentially, his 10 minute FTP is almost his 20 minute best effort. I think I don’t need to tell you that doing efforts at such a highly overestimated FTP isn’t sustainable and manageable for long. You might think he may have blown up the pacing but this isn’t merely a random world-tour pro but a decent time trialist as well. If he doesn’t know how to pace then who knows at all?
Anyway, a promise is a promise so his 5 minute best effort was 552 watts. At the time he weighed around 77-78 kg, which puts him at a solid 5.6 watts per kg at FTP. What I want you to take home from this story is that you are able to produce power at those short FTP tests that even a better correction factor is not able to capture.
Check out the training files below and see for yourself:
An Offer
The point of this article is that you and every other cyclist will experience a huge drop-off in power from your 8 or 10 minute test compared to the standard 20 minute test. For you it might happen at 12 or 15 minutes, for your buddy it might happen at 8 minutes. For the world tour pro it was 10 minutes.
For now there’s no way around the dreadful 20 minute test to get a decent estimate of your FTP. To make things easier for you, here’s my first offer for you: Studies have shown that a simple warm-up instead of the tough original warm up is enough to get reliable results. So now the only thing that stands between you and a solid FTP is a 20 minute time trial without the 5 minutes all-out beforehand. You’re welcome!
However, there is one field test method that few know about but that is based on robust scientific concepts. A field test that is worth my second offer. A field test that isn’t only mentally easier than the 20 minute test but above all more fun and more reliable. A field test able to rule the 20 minute test.
I will drop the link down here, once published. Stay tuned!
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Studies Used in This Article
- Is the Functional Threshold Power a Valid Surrogate of the Lactate Threshold?
- Is the Functional Threshold Power a Valid Metric to Estimate the Maximal Lactate Steady State in Cyclists?
- Comparison of a Field-Based Test to Estimate Functional Threshold Power and Power Output at Lactate Threshold
- A Field-Based Cycling Test to Assess Predictors of Endurance Performance and Establishing Training Zones
- Critical power is positively related to skeletal muscle capillarity and type I muscle fibers in endurance-trained individuals