Determining FTP with an exercise test?

Cycling Tips

Are you curious about your ftp but don’t know where to start with an exercise test. You could do an exercise test yourself. We have developed a number of self-tests and a calculator to estimate your FTP even without a power meter. How this is done, you’ll read here.

What do we normally measure during an exercise test?

With the exercise test we want to determine the FTP and training zones. At one of our locations we start by measuring height, weight and fat percentage. Then we get on the bike and go through a step protocol, men start at 120w, women at 90w. Every 6 minutes the load increases by 30w. Meanwhile we accurately measure heart rate, cadence, power, RPE and prick a hole in your ear to take a drop of blood in which we measure the lactate concentration (in mmol/L). This gives us a good picture of how much acidification is present in your body at that moment. It also gives insight into how much energy is being produced mainly from fats or carbohydrates.

Because we go through the entire intensity spectrum during the exercise test, we get a good picture of both FTP, your lower and higher zones. We can therefore accurately determine both the aerobic threshold, and the anaerobic threshold.

The aerobic threshold is the point at which fat burning is maximal, this is a hugely important point as this is the intensity you can sustain for several hours. This is because once above this point the body switches completely to carbohydrate burning. Then you rush through all your stored sugars (muscle glycogen) quickly. So the aerobic threshold really says something about endurance capacity and up to what sub-maximal intensity the body stays in fat burning. The next point we measure is the threshold, at which the production and breakdown of lactate is exactly still in steady state, also called Maximal Lactate Steady State (MLSS) in science. This point corresponds well to the threshold/FTP (Functional Threshold Power; power you can ride for an hour).

Testing yourself

Above the threshold power, it takes a few more minutes before the acidification gets the better of you and we will abort the test, thereby determining maximum power. This is a good indication of the power you can pedal above your threshold.

Of course, you could perform exactly our protocol on your smart trainer at home, which will allow you to measure your maximum power on this test. However, this defeats the purpose of the exercise test. Without lactate measurements, especially at low intensity, you cannot see where the energy comes from. In addition, you cannot determine your turning point this way.

20 minute FTP test

Using your power meter and/or smart trainer, you can get a good indication of where your threshold point is. You can measure that with a 20 minute FTP test. Here you ride a time trial for 20 minutes. You have to plan it well so you don’t blow up in the first few minutes. This value is multiplied by 0.95 (95%) to get an indication of the FTP. This percentage of 95% can give a overestimateion of the power output at the threshold power, this is very individual and depends on the type of rider you are as well. Especially for riders with a large anaerobic tank; good at releasing anaerobic energy and therefore able to ride in the ‘red’ above the turning point.

There are also other self-test FTP tests you can perform with a power meter. For example, we have several ready for you in the JOIN application, such as a Ramp test, a 12-minute test and even a 4-minute all-out test. It is best to choose a test that suits you well. If the test is too difficult you cannot repeat it once every 6 to 8 weeks. In doing so, always try to keep conditions as similar as possible. Keep in mind that these self FTP tests are not as accurate as an exercise test with lactate measurement.

No power meter

If you do not have a power meter, it is very difficult to estimate someone’s power. This can be done uphill using the climbing times, but unfortunately it is not in our backyard. In order to make a rough estimate of the FTP based on speed, we have created a calculator on our site. This gives an indication and is especially a nice tool to see what happens to the power if you are for example 3 kilos lighter or choose a different posture. Still, with this calculator we can make an estimate and include this in the starting point of guidance.

Measuring performance above the FTP

We normally perform an anaerobic field test with all riders who have a power meter as well. With this, we better measure how good you are at pedaling values above the turnover point. This is also called anaerobic capacity. Of course, for many people the question is how much this matters with the goals they have. For someone doing a cyclo in the mountains where you cycle mostly below FTP, it’s pretty useless. For competitive cyclists (especially in the flat Netherlands) it adds a lot.

During this test you perform some 10-15 second sprints after a good warm-up. Then you also ride for 1 and 5 minutes at full speed, all with of course full recovery in between. With these 3 values (15sec, 1minute, 5minutes) your coach will calculate. Then we look mainly at how far above the turning point we measured that same week in our lab. This gives us a good indication of the values above the turning point and thus how big your anaerobic tank is. Doing regular exercise tests on your smarttrainer and with your power meter in addition to measuring your FTP is the way to see how you are doing.

Determining heart rate and power zones

Unfortunately, it is not possible for a while to do an accurate exercise test with lactate measurement. For this, the lactate measurement still adds too much. Measuring the aerobic threshold and determining the threshold much more accurately. Still, with these self-tests and FTP calculator, we can make an estimate of the threshold power based on speed. With this, your trainer can then determine your heart rate and power zones and we can still maintain or improve fitness in a responsible way even though the goals may be a little far away right now.