Most have likely encountered the term “FTP” in training parlance. The acronym stands for Functional Threshold Power and refers to maximum effort you could produce over an effort of roughly one hour. In comparison to a laboratory blood lactate test, FTP is a representation of work you can actually do, rather than analysis of physiological markers that correspond to a certain level of performance. FTP is commonly assessed indoors or outdoors through the completion of a 20-minute test. Because sustainable power for this duration will be higher than a full hour, the 20-minute test value is reduced by 5% to determine your FTP training value. The testing process is much maligned because, quite frankly, it’s not very fun. There is a lot of suffering if you are going for a truly maximal 20-minute effort, in both a physical and emotional sense. Many athletes are also reluctant to lay all their cards on the table. Particularly during the off-season when fitness is a bit lower, it can be disheartening to do your best and get a number that’s less than it has been in the past. Removing the emotional connection to a given number and understanding how and where it’s used in your training should help make the testing process a little less daunting. So, how and where do we use FTP?

1. FTP as a measure of current fitness. This is perhaps the most important use of the value. Effective training will be based on your current fitness level, rather than some fitness level you’ve held in the past or aspire to attain in the future. Using a current baseline value will help you target the proper intensities for the present, and those workouts will elicit growth that will help you reach or return to the levels you want to achieve.
2. FTP as a measure of training progress. This one is what trips up many athletes. Often, the beginning of a structured training routine will result in several months of consistent growth and rewarding numbers on the 20-minute test performance. Once an athlete maxes out available volume and settles into a consistent routine, these changes will slow, and it will take a new or greater stimulus to elicit further change. If you’ve been training for multiple seasons, it’s natural to have some peaks and valleys in your fitness level over the course of the year. Maintaining a completely consistent fitness level year round is challenging and, in some cases, impossible. What you want to look for is improvement year over year, at similar times of the year or at least under similar fitness conditions (resuming training, mid-season, peak fitness, etc.).
3. FTP as a part of training calculations. Many of the training metrics we use, such as Normalized Power, Intensity Factor and Training Stress Score, all contain FTP as part of the equation. Using an inaccurate FTP value will result in inconsistent and sometimes unrealistic values for these metrics. Training zones are also based on FTP in the VQ system as well as many others. Make sure you update your FTP setting in your training software any time you have significant changes in the value in one direction or another.

The take-home point here is that FTP is not a static value. It can move up and down in response to training or the lack thereof. Fatigue and sickness may adversely affect your ability to hit a target number, while being well rested should allow you to achieve peak performance. Some minor changes are normal, such as 5 watts up or down, and wouldn’t necessarily justify a global change as suggested above. However, more significant changes to your FTP will have wide reaching effects on your training levels and the metrics you get back, so your reference value should be adjusted accordingly. Understanding where FTP is used and applied in your training will help you walk the appropriate line between being obsessive about your performance vs. unaware of changes that will be a part of your reality over time.