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Functional Threshold Power or FTP is the average amount of power a rider can generate for one hour, expressed in watts (w), and measured with a power meter. If you want to train with power, knowing your FTP is vital for setting your training zones, doing the actual training, and measuring improvement.
It is also a critical number in professional cycling. But to understand FTP’s role in propelling a bicycle, we need to contextualize it with rider weight.
Power-to-weight ratio – expressed in watts per kilogram (w/kg) – is what separates amateurs from the pros, and the daily commuter from the Cat. 3 weekend-warrior. When riding uphill, there is no more important factor in determining a rider’s speed than their power-to-weight ratio. (There are certainly other factors involved in a rider’s speed, including aerodynamics, rolling resistance, and overall mechanical efficiency.)
The importance of FTP also differs between types of riders. For a savvy sprinter like Mark Cavendish, whose goal is to win the sprint in the final few hundred meters, FTP doesn’t matter much – a strong FTP will help him be there at the end of the race, but it won’t decide the final outcome. On the other hand, for a time trial legend like Fabian Cancellara, FTP is everything. All else being equal: higher FTP = faster time trial speed.
It is important to remember is that FTP constantly fluctuates – it changes every week, and even day-to-day. Fitness and freshness, caffeine intake, stress, hydration levels, and glycogen stores can and will affect your FTP on a given day. But the more consistent you are in your training and recovery, the more accurate and useful your FTP will be.
So, how the heck do you figure out your FTP?
How to measure your FTP
FTP can be measured by a number of on-bike power tests such as a ramp test, the classic 20-minute romp, or the truly masochistic hour of power.
If you want the most accurate FTP possible, you should do the one-hour power test. It is the definition of FTP – how much power you can put out for an hour. However, most people – I’d venture to say 99.5 percent – don’t do this test. Because it sucks.
The one-hour power test is completely draining, both mentally and physically, and it can take up to a week to recover from. An even better reason to skip it: study after study has shown that alternative FTP tests, such as a ramp test, are just as accurate when it comes to measuring FTP as the full gas hour of power (McGrath, Eanna, et al., 2019). There’s also a lot that can go wrong in an hour. Can you imagine being 54 minutes into an hour-long power test and getting stopped at a light or stuck behind a car? Ouch.
Thankfully the cycling scientists have come up with a few alternatives to 60-minute FTP tests for us: Ramp tests, two by eight minutes, or a 20-minute time trial, to name a few. Here are the protocols for each. Make sure to complete a short warm-up before any of these tests.
Beginning at a very easy pace, target power is increased every minute until failure. Many training environments such as TrainerRoad and Zwift offer this feature. The ramp test on Zwift, for example, uses a starting target power of 100 watts, and increases power requirements by 20 watts each minute. Go till you blow – it’s as simple as that. The ramp test shines because it is short and sweet. There is no pacing involved, the deep sensation of suffering lasts for only a couple of minutes, and it is impossible to “fail” the test – in fact, “fail” is exactly what you’re supposed to do! From this test, TrainerRoad calculates your FTP as 75 percent of the power for the final minute you were able to sustain.
2 x 8-minute test
Ride two, eight-minute intervals as hard as you can, with 10 minutes recovery in between. Take the better of the two intervals (i.e., higher average power) and subtract 10 percent from that number to get your FTP. The main reason that riders chose the 2 x 8-minute protocol over the 20-minute time trial is because it is “easier” due to the shorter interval durations.
Some high-end computers like the Wahoo Elemnt GPS bike computer family come with this FTP test protocol as an included workout.
20-minute time trial
Go as hard as you can for 20 minutes, then subtract 5 percent from your peak 20-minute average power to get your FTP. If you have a highly developed anaerobic system — read: if you’re a sprinter — then subtract 10 percent.
Pacing is key during a 20-minute test, and that is why it is so hard for many athletes to get right. A well-executed test will show the same or slightly greater average power in the second half of the test as the first. A poorly executed test will show a power graph that slowly drops off over time – coincidentally, at the same rate as your confidence.
To improve your pacing, use data from previous efforts and a heart rate monitor to hold yourself back in the first ten minutes, so that you can crush the second half of the test and finish strong.
Zwift has a 20-minute FTP test, and many high-end computers like the more expensive models in the Garmin Edge family come with this workout as an option. Nicer Garmin Edge models can also be set to auto-calculate your FTP based on finding your best 20-minute average power from any recent ride, workout, or race and using the 95-percent formula.
Workouts to improve your FTP
Once you know your FTP, it’s time to improve it. Because bigger is better, right?
When it comes to improving your FTP, it seems you can do just about anything under the sun and it just must work: get more sleep, do more stretching, eat a healthier diet, improve your bike fit, etcetera. Even on the bike, simply riding more can have a positive effect on your FTP. A review published in the Scandinavian Journal of Medicine & Science in Sport compiled data from a number of studies comparing low-intensity and high-intensity training programs. They surmised that “important adaptations appear to occur with low‐intensity continuous training that are not observed with mixed or high‐intensity training,” including increases in VO2max, speed at lactate threshold, and “intense exercise performance” (Laursen PB, 2010).
While ‘riding lots’ has its benefits, most of us simply don’t have the time for 20 hours or more of training per week. And this brings us to high-intensity interval training, or HIIT. Any well-executed set of HIIT intervals will make you faster when balanced with rest and stuck into a balanced training week. But if you’re looking for FTP-specific gains, here are a few key workouts:
3 x 10-minute FTP intervals
Complete three, 10-minute intervals at 100-110 percent FTP with 10 minutes easy in between each interval. These intervals can be done on a climb or flat stretch of road, and are best-executed when the average power of each interval stays the same.
More advanced riders can progress to 3 x 15-minute intervals at 100-105 percent FTP, and then 3 x 20-minute intervals with 8 minutes rest for the elites who really love to suffer.
4 x 15-minute sub-threshold/Sweet Spot
Coined by FasCat Coaching’s Frank Overton, ‘Sweet Spot’ refers to riding at 84 to 97 percent of FTP, and strikes a unique intensity that promotes physiological adaptations without wearing down the body as much as threshold or VO2max intervals.
A total of 40 to 60 minutes of Sweet Spot work is the goal duration for these interval sessions, with rest periods being 50 to 70 percent of each work period – 10 minutes rest after each 15-minute interval, for example. Sweet Spot intervals can help build up your aerobic engine without too much fatigue, making for a powerful and sustainable training period.
Wait, what? Stay with me. Proper recovery blocks will boost your FTP more than any super-structured, lung-busting set of hill intervals. In fact, training makes you tired, and it is only after proper rest and recovery that we get stronger.
One rest day per week is a good rule of thumb for endurance athletes, as well as a rest week once every four weeks where training volume is reduced by 30-50 percent including an extra rest day or two.
Re-Testing Your FTP
Serious cyclists can expect to re-test their FTP once every four to six weeks. Any more than that is unnecessary, and unlikely to show accurate and significant changes. For more novice fitness enthusiasts, it is still important to re-test your FTP a few times a year – during the off-season, base, build, and racing seasons, for example.
Re-testing your FTP will keep your power-based training zones accurate, which, in turn, will help you get the most out of your workouts and maximize your fitness without burning out.
You can think of it two ways: If you have set your FTP and thus your training zones too low, your workouts won’t be hard enough and you will be missing out on important fitness gains. If your FTP is too high, you are likely to fail workouts (which hurts as much mentally as it does physically) and you will be at a higher risk for overtraining, injury, and burnout.
Save yourself and be honest about your FTP! (That said, when someone asks you what your FTP is, feel free to add 50w.)
Laursen PB. “Training for intense exercise performance: high-intensity or high-volume training?” Scandinavian Journal of Medicine and Science in Sports. 2010; 20 Suppl 2:1-10.
Overton, Frank. “How to Sweet Spot”. FasCat Coaching. Apr 6, 2020.
McGrath, Eanna, et al. “Is the FTP Test a Reliable, Reproducible and Functional Assessment Tool in Highly-Trained Athletes?” International Journal of Exercise Science. Vol. 12, 4 1334-1345. 1 Nov. 2019