Functional threshold power (FTP) or the anaerobic threshold is often seen as the ultimate performance indicator for cycling. The definition of FTP is actually the maximum power output you can maintain for one hour. It is possible to test, train, improve and follow the progression of your FTP using different test (see our previous blogs about progression and FTP testing). The power or heart rate at the anaerobic threshold is also used to calculate training zones to gauge your workouts on. A lot of riders strive to improve their FTP to ride faster, further, fatigue less, recover better and become a more all-round cyclist. Therefore, improving FTP is a big target for a lot of cyclists.

Two thresholds

At first sight it makes sense that in order to improve your FTP, you just have to train at FTP… a lot. However, this is unfortunately a bit oversimplified and definitely not the best and only way to do it. To clarify this, we first need to explain a couple of basic principles. When exercise intensity increases, more and more emphasis is laid on the anaerobic system because the aerobic system can’t produce enough energy to cycle at the increasing power. Therefore, there is more lactate produced when intensity increases.

The first threshold is actually not your FTP, but a bit lower where clearly is an increase in lactate above resting levels (often set at 2mmol of lactate). This first physiological marker is named the aerobic threshold. The second one is the anaerobic threshold or FTP. This is the point at which the production of lactate is in balance with the removal/buffering of lactate. This is the maximum intensity at which your body is in a steady state and therefore FTP is defined as the intensity at which you can hold for 60 minutes. This isn’t actually really the case and there are big individual differences, but to not make things more complicated, we assume FTP is a good estimation of the maximal lactate steady state.

Using these two thresholds make it possible to have a three zone model that is mostly used in scientific studies about intensity distribution. These zones are below the aerobic threshold, between aerobic and anaerobic threshold and above the anaerobic threshold.

Remarkable finding

In retro perspective, studies noticed a remarkable finding: in a lot of endurance sports (like cycling, running, swimming, rowing, cross country skiing), elite athletes don’t train that often at their FTP. Instead, the pro riders have a more what is called ‘polarized training distribution’. Meaning that they did a lot of training below the aerobic threshold, and some training above the anaerobic threshold. So just almost no training was done in between the zones and at their FTP. Almost 80% of their training sessions was done at a low intensity (below the aerobic threshold) and around 10-20% of the training sessions above the anaerobic threshold using hard interval training.

After this finding was first discovered, a lot of studies were done studying this typical training intensity distribution and measuring its effectiveness. This was done in many endurance sports and at all levels. Interestingly enough, almost all outcomes suggest that also for recreational athletes training 6 hours a week with the polarized distribution gave the biggest improvements in their FTP compared to training more between the two thresholds.

The main reason behind it is quite simple. Exercising at your FTP is really fatiguing, but you’re not recruiting all your muscles and also your heart and lung system aren’t at their max capability. So, you get fatigue a lot but the training stimulus is less intense than exercising above the anaerobic system.

The take-home lesson is that in order to improve your FTP, it is really important to take a look at the intensity distribution of your workouts. Most recreational cyclists just take their easy workouts too hard and their hard workouts too easy. So, train like a pro and make sure you train polarised enough to improve your FTP.