Functional Threshold Power, also known as FTP, is the maximum amount of power that you can sustain over one hour. It’s measured by watts per kilogram, which is the power produced divided by the cyclist’s weight. FTP is mostly used to measure the fitness level of a cyclist along with weight and heart rate. FTP is a moving metric, meaning the results of testing FTPs vary depending on the circumstances and environment. It increases with training but decreases if the athlete has over-exerted themselves. You need to have a power meter to measure FTP.
Besides doing a one-hour time trial and just taking the Normalised Power number as your FTP, you can also measure FTP with a standard 20-minute test.
This is the format provided in Training and Racing with a Power Meter by Hunter Allen and Andrew Coggan, the seminal work on using power in cycling.
(Note that the test proper takes 20 minutes not including warm-up and cool-down.)
Multiply the 20-minute average power number by 0.95 to give you your FTP number. Many softwares like Strava, TrainingPeaks, and Today’s Plan actually compute this number automatically when they detect that you’ve done an FTP test.
Allen and Coggan’s test simulates the maximum effort you can sustain for an hour, but minimizes the lactic acid build-up. The 20-minute test is easier on the knees and joints and faster to recover from, which is a good thing if you have more training coming up during the week.
Coaches develop plans using percentages of FTP to create “training zones” or “power zones”; time spent in each of these zones will help build an athlete’s aerobic, anaerobic, max effort, and sprinting capability. This makes training more effective because you have a tangible target to push towards within each training session.
Coggan defined seven power zones which correspond to how your body responds during a race or training session.
% of FTP
Rate of Perceived Exertion
Easy spinning; active recovery
Long Steady Distance; age-group athlete Ironman effort; 90 min-2 hr
Brisk group ride; elite IM, age-group half-IM effort; 20-60 min steady
Includes FTP; time trial or Olympic distance tri effort; Interval training 6-20 mins, ¼ recovery
Bike race surge; interval training 2-6 mins
Criterium bursts; 30sec-2 min, effort very high
Short, very high intensity sprints
As you become more fit, pushing the target power for these training zones will take less effort; if you’re tracking heart rate along with power, you’ll find you’re sitting in the lower end of the heart rate range for each zone. This is why it’s also important to test FTP periodically so you know if the training is effective. FTP test results help you chart your strengths and weaknesses as a rider, allowing you access to which areas of your game you need to maintain or shore up on.
Since FTP is w/kg, if you decrease the denominator then the resulting number is larger. The simplest way to improve FTP is to lose weight and continue pushing the same power -- but that’s easier said than done, because weight loss improperly done brings with it muscle loss, and thus power loss.Strength sessions help increase FTP because they build muscle, as well as improve muscle endurance pushing heavy gears.
Try a 2x20 interval session, which is two 20-minute intervals separated by a five-minute easy-paced recovery. Target a pace you can maintain and not blow up on the first interval. For the next interval, maintain the same pace as the first but make sure to pour out everything at the end. If you do this correctly, your power or pace shouldn’t have much of a drop-off between the two intervals.
However, the most efficient way to improve FTP is to follow a training plan specifically designed to do that. If you subscribe to Zwift, they have a 10-12 week FTP Builder. Such training plans are designed so that you spend the right amount of time in the proper power zones. Do this, and watch that FTP climb!
(Header photo by Simon Connellan on Unsplash.)
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