New Perspectives on The FTP Test

In 2006 Allen & Coggan, authors of the famous book *Training and Racing with a Power Meter, founded functional threshold power, in short FTP. Ever since FTP evolved into the most talked about metric in the world of cycling.

I think this fame can be partly attributed to its simplicity and comparability; own a power meter and you can determine your FTP and compare yourself to others. From the bloody beginner to the powerful pro cyclist. All you need is a 20 minute all-out test and a 95% correction factor. But does this correction factor holds true against science or not? In this article I want to show you new perspectives on probably the most discussed variable in cycling.

But before we get into it, let’s do some quick history around FTP.

The History of FTP

In the following quote, Allen and Coggan explain what FTP is and describe how it affects our performance around it:

“FTP is the highest power that a rider can maintain in a quasi steady-state without fatiguing. When power exceeds FTP, fatigue will occur much sooner (generally after approximately one hour in well-trained cyclists), whereas power just below FTP can be maintained considerably longer.” – Training and Racing with a Power Meter by Allen & Coggan

Basically, your FTP is your max hour power. But since a 60 minute test is too hard for most cyclists, Allen and Coggan researched the relationship between the 20 and 60 minute power. What they found was that at mean, in over 100 cyclists for example, 20 and 60 minute power deviated at 5%. For example, if you bang out 20 minutes at 300 watts and 60 minutes at 285 watts, you get a 5% deviation.

Apparently though, the margin of deviation was quite big in all these individuals, called standard deviation. So, there were some cyclists with a 90% correction from 20 to 60 minute power and some with a 97% correction, for instance.

This should be enough of a background around FTP, so let’s move on to the original FTP test protocol.

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The OG FTP Test Protocol

If you want to determine FTP from a 20 minute test, there was a corresponding test protocol developed as well. Here’s how it goes:

20 min warm-up at 65% of FTP
3×1 min 100 rpm fast pedaling, 1 min rest in between
5 min easy riding at 65% of FTP
5 min all-out max effort
10 min easy riding at 65% of FTP
20 min all-out max effort
10-15 min cool down easy riding at 65% of FTP

Now, what should catch your eye immediately is the long warm-up before the actual test. In total you spend 46 minutes before the 20 minute test. Besides, you have to go 5 minutes all-out during the warm up. Meaning the warm up itself is extremely hard already. If you’ve done a 5 minute all-out test yet, you know how hard it is to recover from such an effort. Honestly, the last thing I have in mind after such a demanding effort is an even longer one.

However, the idea behind the 5 minute TT is reducing the anaerobic contribution of the 20 minute test by emptying your anaerobic battery and therefore justifying the 95% correction factor.

Interestingly, Spanish researcher Barranco-Gil and his team investigated the effect of different warm-up protocols on the 20 minute test, including the original warm-up with the 5 minute test, a 10 minute warm-up at 60% VO2max or no warm-up at all. What they found was that the warm-up had little effect on the 20 minute effort. Subjects achieved similar power output with all three warm-ups.

Now, some coaches like to include the 5 minute test during the warm-up to get another important metric: The maximum aerobic power. Called MAP in short it describes your time-to-exhaustion at 100% of your VO2max. Yet in a study, Grappe and his colleagues showed, by extrapolating data from the power-duration curve, that 3.5-4.5 minutes better represent MAP. They got 4 minutes at MAP on average and claimed that a 4 minute trial might be a better approximation of MAP.

Therefore, I think that the long fatiguing warm-up is of no value for the athlete nor the coach and a standard easy warm up will get the job done much better. And this is exactly what Lillo and his colleagues did in a study to further simplify the 20 minute test and give us a new perspective on what it is and what it isn’t.

On white background in blue color it shows the original ftp test protocol with a warm up, the 5 minutes all-out as well as the 20 minutes all out all highlighted in blue color. — The original ftp test protocol had you perform 46 minutes of hard riding before even starting the actual test

Your FTP is Not 95% and Lactate Matters

Studies investigating the correlation between FTP, the second lactate threshold (LT2) and the maximal lactate steady state (MLSS) always came to the conclusion that FTP based on a correction factor of 95% very largely overestimates the lactate counterparts.

In addition, research from scientist and Ineos coach Dajo Sanders found that the short 8 minute FTP Test with a 90% correction factor also overestimated lactate counterparts. So even at shorter tests with a lower correction it still isn’t low enough.

Your MLSS, however, is important as it defines the point where lactate production and clearance remain at equilibrium. For example, if you ride at your MLSS for 30 minutes and I measure your blood lactate at 10 minutes and 30 minutes into the test, your blood lactate concentration should increase by less than 1 mmol/l blood. This is also what the term steady-state stands for.

Once you cross your MLSS, lactate starts to accumulate and you will reach VO2max and exhaustion, rather quickly, depending on how long you maintain a certain intensity above your MLSS.

And this is where things get interesting. A study comparing lactate kinetics between amateur and pro runners found that not only do pros have lower lactate measures in general and reach their MLSS later into a ramp test but pros also accumulate lactate at a lower rate above their MLSS. This makes sense because Burnley and colleagues in their work around critical power, which is slightly higher than MLSS, found that CP is closely related to your enduring type 1 muscle fibers, and even better correlated with your capillary density.

In other words, the aerobic machinery and their supporting structures that are highly involved in lactate clearance determine your MLSS. So MLSS in fact represents the highest rate of aerobic metabolism.

Apparently, a 95% correction on average just seems too high, which is good because we know now that we have to go lower. But how low? Let’s talk about that now.

Toward a Better Approximation of MLSS

That MLSS represents an important typing point where the body finds a delayed steady-state should be obvious now but how can we find that point where pain and relief come together? This is the question that Spanish researcher Lillo-Beviá and his team tried to answer.

So they took 11 cyclists and triathletes with a relative VO2max of 55-65 ml/min/kg in a series of lab tests to determine their MLSS, maximum aerobic power, as well as ventilatory threshold 1 and 2. Afterwards the participants had to perform the 20 minute time-trial with an easy warm-up where they measured their power output and put that in relation to their MLSS power output.

The 20 minute test was an important choice as it shows a low margin of error with a high reproducibility. That means if you perform the 20 minute test in a close period on the same road or climb with similar conditions in terms of freshness, sleep, caffeine etc. you will get similar results. This is crucial if you choose a time trial to assess your performance and transfer training zones.

The same is true of course if your ride the 20 minute test on Zwift. Noteworthy, some riders produce less power indoors than outdoors. In this case you need to test both occasions. Personally, I see no difference between outdoor riding or on Zwift. Therefore, it doesn’t make a difference where I perform the test.

So if you improve your 20 minute power you can say that it’s due to improved performance and not fluctuation of the test results. Additionally, a higher 20 minute power is associated with an increase in MLSS also.

Back to the study results, Lillo and colleagues found that 91% at mean and not 95% was a better correction factor to approximate your MLSS. In fact, statistically 90% of the participants fell in the 90-92% correction factor, while only one participant showed an 88% correction factor and one represented the higher end with a 95% correction factor.

Avoid pain when it’s unnecessary. A simple warm up before the 20 minute test is all you need.

In Case of Confusion Choose a Lower Power

While a lower correction factor of 91% from the 20 minute test is a better approximation of your MLSS, there will always be outliers. So the 88% guy would still overestimate MLSS by 3%.

Therefore, individualization is key because everyone has a different performance profile.

Yet, Lillo suggests underestimating MLSS instead of overestimating it in case of uncertainty. He also looked at what happens when participants exceed their MLSS by just 8-10 watts. Surprisingly, participants could barely pedal for 30 minutes before exhaustion and some had to stop earlier. On the other hand, when staying at or slightly below MLSS the participants were able to maintain that power for up to 90 minutes.

Now, when we go back to the study on pro and amateur runners this makes a lot of sense. If you’re an amateur you will reach acidosis quicker above your MLSS and you will also go really deep in it. On the other hand, underestimating your MLSS by 10-15 watts will give you a pretty similar stimulus while avoiding the huge accumulation of lactate and the fatigue you create with it.

MLSS as a Fatigue Threshold

Talking about fatigue, Burnley and his group found at least at critical power in an isometric state, which is critical torque, that muscle fatigue at 80-90% below critical torque occurs at 4-5 times slower compared to above the critical torque. Now, while we can’t completely transfer that to cycling, as one muscle group is only used in an isometric state, it still shows that critical power and also MLSS represent a certain fatigue threshold.

Just compare tempo intervals with a really tough HIT session. I can only speak for myself and know that HIT will produce more fatigue in a shorter time than tempo.

In addition, from experience with my athletes, for some doing threshold intervals at a 95% correction factor from the 20 minute test, they were hardly able to complete a 5×10 minute set and complained about huge fatigue afterward. Furthermore, they gave me feedback that after HIT sessions they felt much better compared to the mentioned threshold session.

Once we reduced the correction factor to 90%, though, they were able to finish a threshold sessions without complications.

I would even argue that if you overestimate MLSS you are better off sticking to a polarized intensity distribution and investing in HIT and sprint sessions rather than threshold sessions.

So instead of searching for a higher FTP less is more when it comes to MLSS. I suggest you start with a 91% correction factor for the 20 minutes test and an 86% correction factor if you are only able to complete a 10 minute test due to your training environment. Once done you can adjust according to your perceived exertion and heart rate and lower or upper your MLSS. At least a study on running threshold power found that a 90% correction factor for a 20 minute test and an 85% correction factor for a 10 minute test is acceptable. In each case you follow a conservative approach.

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There Will Always Be Your Heart

One thing I always tell my athletes is listening to their body and looking at their *heart rate. There is research on professional endurance athletes showing that blood lactate and heart rate correlate over a season. While this is not true for recreationials, it shows that heart rate is a valid marker of internal load.

Sure heart rate reacts to caffeine, sleep, stress among others, but yet it shows us when we ride below our limit. Therefore, I suggest you find your maximum heart rate as it’s individual to you. Of course you have to measure it and find a way to reach it and avoid any formula you find. For example, I approach max heart rate in an intense race. For you it might be a 4-5 minute test or even a 20 minute test.

Once you determine your maximal heart rate, I suggest the heart rate zones from the Norwegian Olympic Federation. Based on their zones, threshold or zone 3 ranges from 82-87% of max heart rate. For example, my max heart rate is around 194 bpm. Accordingly, my zone 3 ranges from 159-169 bpm. When I’m hitting threshold intervals I double check my heart rate to stay in that range once settled and compare that to my perceived exertion.

What I want you to take from this section is that using a range rather than a fixed point is important. Depending on many factors your heart rate will be higher or lower at a given day but it should stay somewhere in that zone and feel right.

There’s No Fixed Point in Your Body

Based on what I wrote before, I want you to realize that there is no fixed point in your body. Indeed, your body doesn’t know systems or zones nor does it care about them. Following this, there’s no cut-off at any intensity in your body. Instead, all energy systems work at all times with different contributions to the output, meaning that your MLSS is a floating range rather than a fixed point.

Heat, stress, fatigue, and sleep can all change your daily MLSS. Therefore, it’s more of an improvised science and some sort of leeway.

If I say my MLSS translates to 360 watts at a 91% correction factor from my 20 minute test, what I actually mean is it probably ranges from 340-370 watts. And at the end of the day the exact number doesn’t really matter. What matters more is setting targets to stress our body appropriately over and over again that in turn will make us faster.

So I hope that these new perspectives will guide you to a more comprehensive look at your body. But most importantly, I hope you to realise that in a sport where everyone strives for more, more is not always better.

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