3 Very Reliable Ways to Determine FTP (Including Test-Instructions)

20min FTP test in cycling

The FTP is one of the fundamental metrics to assess an athlete’s capability on the bike. 

A proper FTP test delivers you with the desired data to extrapolate the different training zones and more. FTP stands for “functional threshold power” and basically is the power in watts a cyclist can sustain for an 60 minute paced all-out effort.

There are, however, different methods to obtain FTP data with some being inaccurate and some establishing themselves as very useful for. Today I will show you the top 3 test protocols with instructions to get the best out of your performance.

1. The Pro Default: Advanced lab testing

Visiting a lab to gather data of your current physiology isn’t always easy. At first you need to find a modern lab that delivers you with everything you need. But it can be worth the effort and money as you will get a comprehensive insight of your capabilities.

An advanced cycling lab won’t just give you a FTP value and bounce you out into the wild world of cycling. No, they will supply you a whole metabolic profile by extrapolating your maximum lactate steady state (MLSS). MLSS is what FTP often stands for. A steady state, where lactate production and clearance is at an equilibrium. 

This is done by undergoing several tests. It usually starts with a 20 seconds all-out seated sprint, where lactate is measured at rest, before and for several minutes after the effort. This way you will get your maximum lactate production rate (VLamax) measured in mmol lactate per liter blood per second (mmol/l/s). This actually describes your anaerobic capacity. As an endurance athlete you usually want this to be in the lower range. 

The next test is often a ramp test with a spiroergometry mask that measures gas exchange of oxygen and carbon dioxide. Thereby, VO2 can be measured and a whole metabolic profile including MLSS, your individual fatmax zone (aerobic threshold, where fat oxidation is highest) as well as carbohydrate and fat consumption, can be rendered. 

The last round is usually a VO2max test: An all out ramp test, where steps grow faster and in shorter time. Thereby you will really push your limits. And with the mask on obtain your maximum oxygen uptake or aerobic capacity. 

A modern lab test that supplies you with all the described data is a great way to understand your individual physiology and metabolism. You will get your FTP and so much more. Therefore, training can be planned toward what should be improved. Like threshold or VO2max for instance. 

2. Field Testing: Inscyd Perfomance Decoder Test

The company Inscyd delivers the lab testing to go. By gathering loads of data of pro cyclists, pro triathletes and other athletes they build a complex system of algorithms that deciphers the physiology and metabolism of an athlete. 

This is done by the insight that power and oxygen uptake raise linear. With a scientific relation of oxygen cost and lactate, inscyd delivers a whole metabolic profile as well as VLamax and VO2max. 

You can do the test from wherever you are in the world. Outside on the road in the field or insight on zwift. This kind of “FTP test” is all-encompassing. From your individual recovery zone, to the fatmax zone, to lactate accumulation. Inscyd delivers. But, you need to find a lab or a coach that provides inscyd testing, can interpret it and review the data with you. 

Inscyd test procedure

The whole protocol consists of 4 different tests. Usually spread over two sessions with a recovery day in between for optimal results. On the first day you do a standing all-out sprint of 20 seconds out of complete rest. Once done stop pedaling for some time, record it all and ride easy. Then starts the second test with a 6 minute all-out paced effort. Congratulations you completed day one. 

The second test session involves two more tests. After a warm up you need to do a 3 minute paced all-out effort. Ride easy for 15-20 minutes and do the last test: 12 minutes all-out paced tt-ish effort. Check, day two done. 

Staying seated during all the efforts as well as recording the whole session including breaks with your garmin edge 530 or whatever you use is the basis for reliable results. 

3. The Famous 20 minute FTP Test

The 20 minute FTP test is the most widespread protocol to obtain FTP data. In this way you can derive individual training zones and capabilities. Having been criticized in recent years due to inaccuracy compared to advanced lab testing and all, I think the 20 min test is still valid. As I compared lab data to the 20 min test, it works for me. There’s more to it than just an all out effort.

And it highly depends on executing the FTP test right. 

So, let’s elaborate what you should pay attention to, if you want to create a test setting that is reproducible and reliable: Firstly, get used to doing FTP tests on the indoor trainer on zwift or on a road, where you can ride uninterrupted. Secondly, it’s critical to remain seated for the whole test duration. Pace it smoothly. Thirdly, do a 2-3 minute seated all out interval to get ready for the test and thereby reduce the anaerobic contribution. 

Analyzing the test result

If done correctly, upload the data into trainingpeaks and analyze it. For the interval you want your Variability Index (VI) to be as close to 1.00 as possible. Up to 1.04 should be okay. This ensures that you don’t overestimate your FTP. Because the greater the VI the more variable and inconsistent the effort it.

Now, take the average power for the 20 min test and and multiply it by 0.95. Voila you have your FTP. Let’s say you averaged 400 watts. Then 400×0.95 results in a 380 watt FTP. By collecting data about yourself you will likely find that your maybe more anaerobic and need to subtract more percentage like 0.93 or even 0.9. It’s a bit individual.

And it’s not only data you get with the test. Because when you put yourself in the hurtbox for so long you will learn a lot about yourself. And you’ll get used to riding at such high powers. In addition, the test is highly variable. You can do it at the end of a ride with tempo work to mimic race demands and see how you perform at threshold, when fatigued. 

And as you can see it’s not about the highest average power at all cost. Because in the end it’s about meeting the goal of a FTP test: Gaining the right training zones for yourself. Because only then can you train in the right zones and set the intended training stimulus.


What kind of test you use depends on your possibilities as well as your preferences. However, if you decide on a method you’re happy with, stick to it. And always do the same protocol on the same set up (road or zwift) and stay seated. Same procedure. For an FTP Test a climb or flat doesn’t really matter as you pace yourself all-out. Choose the option you’re more comfortable with. 

Now, go out and get the test done. 

And I’m curious what kind of method you use. Let me know in the comments.


The concept of maximal lactate steady state: a bridge between biochemistry, physiology and sport science: https://pubmed.ncbi.nlm.nih.gov/12744715/#:~:text=Abstract,a%20continual%20blood%20lactate%20accumulation.