Functional Threshold Power (FTP): What it Means to Cyclists

Answer: FTP stands for Functional Threshold Power and is an estimated measure of your highest sustainable power, measured in watts, that can be held for one hour. FTP is used to determine training zones that are associated with particular physiological responses and allow you to design workouts and structured training plans that address specific types of fitness.

Expanded FTP Explanation

Function Threshold Power (FTP) is a measure of your ability to maintain a high — but manageable — power output for a somewhat lengthy duration. From a physiological perspective, it’s the point at which your lactate production has risen, leveled off, and then closely matches your body’s ability to remove lactate. This just barely keeps that lactate flooding at bay. In other words, it’s that grey area between the power you can sustain for a very long duration, typically an hour, and the fleeting power you can only tolerate for a couple of minutes.

FTP is supposed to be analogous to a rider’s hour power, but for most, it is not, and that’s okay. As long as you accurately assess your FTP (here’s a resource for how to do that) to get the best possible estimate of your fitness, you can get faster.

What FTP Means for Cycling

Functional Threshold power, on a deeper level, is the balance point between energy supply and demand. Specifically, FTP is the balance between your aerobic and anaerobic energy systems. In general, when you are cycling at low intensities, you are using your aerobic system. The aerobic system uses oxygen to metabolize fuel to create the needed energy. When your aerobic system can meet the energy demands of your muscles, there’s less contribution from your anaerobic energy system.

However, when you are cycling at higher intensities, the anaerobic system contributes more. The anaerobic system metabolizes fuel sources without oxygen and creates energy much faster. As you work harder, the oxygen you can use tops out, even as your leg muscles require more energy, which will begin to overwhelm the anaerobic system. As you continue cycling at high intensities, lactate produced by the anaerobic system accumulates in the muscles. Your breathing ramps higher, your legs start to burn, and your time at this power output becomes very limited.

There’s a harmony between energy systems, and a ‘lactic balance’ is achieved just below the point of overwhelming the anaerobic system. This metabolic steady state, often termed your lactate threshold, actually correlates really closely with your FTP. So much so, that the two terms are basically synonymous.

Why FTP is Important to Cyclists

FTP is significant to cyclists for many reasons, but at the center is its importance for training. An accurate FTP guides a cyclist’s training intensity and reveals the accumulation of training stress. This is vital for training so that it will be hard enough to challenge you while remaining sustainable over time. 

By knowing your FTP, you’re able to customize every workout so that you are stressing the right energy systems. In other words, FTP lets you optimize training to your current fitness level. Also, FTP will help you quantify the amount of training stress you are racking up. This is an important metric to track. Too little stress lacks the needed stimulus the body requires for adaptation. Too much, and you’ll overpower the body’s ability to recover. The good news is that TrainerRoad does both for you automatically. 

TrainerRoad training plans include regular FTP tests. At the beginning of every training block, you’ll complete the Ramp Test to ensure the most effective training. Additionally, training plans are designed to increase training stress progressively, thereby providing the stimulus for consistent and lasting fitness gains. Structured training is that stimulus, and stimulus paired with adequate recovery is precisely what you need to get faster.

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