What is FTP and why does it matter for cyclists?
What Functional Threshold Power means, how to test it and how to improve it
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FTP stands for Functional Threshold Power, which is defined as the highest average power you can sustain for approximately an hour, measured in watts.
FTP is one of the most common training metrics used in cycling and is frequently used by coaches as a benchmark metric and to determine training zones when using a power meter, while the latest training apps also use FTP to set workouts and training plans when using a smart trainer.
In this guide, we’ll look at how to determine your FTP, what you can do with that number, and how to improve your FTP. We’ll also consider why FTP might not always be the best number to use to guide your training effectively.
How to determine your FTP
Indoor cycling apps such as TrainerRoad, Wahoo SYSTM and Zwift use Functional Threshold Power to calibrate workout intensities. For example, Zwift may call for three-minute intervals at 120 per cent of your FTP, with two-minute recoveries in between.
Cycling coaches use FTP in the same way – to measure progress and to personalise specific training intensities. This is the same process whether working with WorldTour team riders or keen amateurs.
The previous standard, lactate threshold, involved measuring blood lactate every few minutes while ramping up intensity on a trainer.
Dr Andrew Coggan, co-author of Training and Racing with a Power Meter, created the FTP standard as a more practical approach. In functionality, training to lactate threshold and FTP are very similar.
“FTP has become the gold standard,” says Scott Moninger, a former professional cyclist and coach for Velocious Cycling Adventures. “Whereas a few years ago you had to go into a lab, now you can get that number with a power meter and a 20-minute field test.
“In a perfect world, I’d get a cyclist to do a 60-minute time trial, but I can’t ask people to do that,” Moninger says. “Even if you removed the realities of traffic and stoplights, a 60-minute time trial is very difficult to do.”
So Moninger and most others use a 20-minute field test with a power meter.
How to find your FTP with a 20-minute test
To measure your FTP, you need a bike with a power meter or a smart trainer with an integrated power meter. A bike with a power meter is ideal because you are generally able to generate more power outside than when you’re on a fixed bike inside.
The key, however, is to make the test repeatable, so you have consistent results from one test to the next.
After a good warm-up, including one or two hard efforts of four to five minutes, ride as hard as is sustainable for 20 minutes.
Moninger recommends finding a road grade of anywhere between 2 and 4 per cent if possible because this will engage more of your glutes and back muscles and result in the best possible power.
“I see differences of between five and 15 watts, depending on the person,” Moninger says. “It’s the same with a trainer, and it’s the same reason power on a time-trial bike is lower, even for the best TT riders in the world.”
Once home, go back and look at your average power for that 20-minute effort. You can use Garmin Connect, Strava, TrainingPeaks or Golden Cheetah to do this.
You can also just use your Garmin, Wahoo or any other compatible bike computer – just remember to start and stop a lap for your 20-minute effort.
Once you have your average 20-minute power, subtract 5 per cent and you have your FTP.
What can you do with your FTP?
Learn what effort levels are sustainable for different durations
The first time you do a 20-minute test, you will probably start out too hard and see your wattage number gradually fade – even if the effort feels the same, start to finish.
This shows why it’s helpful to have a power meter quantify your power production instead of just relying on feel.
The more you ride with a power meter, the more you will understand your abilities. Starting a 20-minute climb? Let your buddies blow themselves up going hard for the first couple of minutes while you carefully pace out your effort, riding at your FTP.
Chris Froome has received plenty of flack over the years for staring at his computer during critical Tour de France stages as he monitors his effort. But you know what? He rode within his capabilities – and he’s won the Tour four times.
Measure your improvement
How do you know if you’re getting fitter and faster? Because you beat your training buddy up a hill? Or because you bettered your time at your local time trial?
These are useful, but not exactly scientific. Your buddy could have been under the weather and the TT might have had a screaming tailwind. Measuring your FTP is similar to standing on a bathroom scale – that number ain’t gonna lie.
Moninger recommends testing your FTP every four to six weeks during the season.
How your FTP compares to another rider’s is irrelevant. The highest FTP is not what wins a race. The highest power-to-weight ratio will likely win a hill climb and the highest power-to-drag ratio will likely win a flat time trial. But the FTP number in and of itself is not a comparative metric – it’s your personal number for specific training.
Speaking of that bathroom scale, if your FTP is going up and your weight is going down, you are going to go faster. Period.
Calibrate your training zones
One of the first things training software programs will prompt you for is your FTP.
Plug in this number and the program will do the rest, whether this is TrainerRoad, Zwift or something else. Many of these programs have built-in tests to help you measure your FTP (Zwift offers either a 20-minute FTP test or a ramp test).
If you are using a training plan from a book, a magazine, a coach or elsewhere, it will prescribe training by zones. Usually, there are six or seven zones (depending on the coach’s or company’s particular philosophy).
For training with power, these are based on your FTP and are often determined like this:
| Zone | Name | Heart rate (% of threshold HR) | Power (% of threshold power) | Typical duration |
|---|---|---|---|---|
| 1 | Active recovery | Less than 68% | Less than 55% | n/a |
| 2 | Endurance | 69-83% | 56-75% | 3+ hours |
| 3 | Tempo / Sweetspot | 84-94% | 76-90% | 20 mins to 1 hour |
| 4 | Threshold | 95-105% | 91-105% | 10 to 30 mins |
| 5 | VO2 max | More than 106% | 106-120% | 3 to 8 mins |
| 6 | Anaerobic capacity | n/a | More than 121% | 30 seconds to 3 mins |
When you hear people talk about doing a tempo ride, or an endurance ride, what they are talking about is training in those specific zones.
Training zones can be just as important for easy training days as hard ones, helping you to recover effectively and avoid overtraining.
Cyclists are often guilty of going too hard on easy days and are then unable to go as hard as needed on very hard days.
- Read more on training zones
How to improve your FTP
In short, train. Instead of just riding along and hoping for the best, spend time riding in zones three and four.
Cyclists will naturally settle into riding at endurance pace (often referred to as base training), which is helpful for building a solid base for long, steady rides. But the biggest gains for FTP come by pushing near or above that threshold.
Frank Overton, founder and head coach at FasCat Coaching, has, for a decade now, been a big proponent of sweetspot training as a way to raise FTP and generally be more productive with your training time.
He and other coaches define the ‘sweetspot’ as an overlap between the top end of zone three (or ‘tempo’ riding) and the low end of zone four.
Overton recommends working sweetspot training into group rides or climbing efforts, but for those who want specific intervals he suggests:
- 4 x 15 minutes between 84 and 97 per cent of FTP; 10 minutes easy riding between efforts
- 2 x 20 minutes between 84 and 97 per cent of FTP; five minutes easy riding between efforts
What are the drawbacks of FTP?
Tom Bell, co-founder of High North Performance, and BikeRadar coaching contributor
FTP testing has, in some respects, become an essential cycling test, given that many training platforms use this as the key metric for establishing training intensities and measuring training load.
However, it’s important to note that it does have limitations.
In particular, rather than doing a full ~60-minute time trial, the vast majority of cyclists will complete some form of abbreviated FTP test (such as the 20-minute test mentioned above).
These tests all rely on assumptions about your physiology and the relative energy system contribution during the test.
In many cyclists (particularly those who are time-limited and/or perform a high proportion of training above their threshold), the FTP estimate from these shorter tests can notably over-estimate the power that could be produced for longer durations.
The problem is compounded by the fact that FTP tests are highly sensitive to your performance on the day, which can be influenced by factors such as how well the effort was paced, motivation levels, fatigue state and fuelling, to name a few.
As a result, if you use FTP to set training zones, you could be training too hard, and any improvements you see in your FTP might not translate to the real-world demands.
Additionally, while FTP has arguably become the universal indicator of overall cycling performance, it’s not appropriate to all disciplines.
For example, if you’re training for a short event, then other markers of performance such as VO2 max and anaerobic capacity will be much more relevant than FTP.
Likewise, very long endurance events, such as long sportives or multi-day races, can be influenced more by factors such as exercise economy and fat oxidation ability, which are not captured particularly well by FTP.
Ultimately, FTP testing can help to reveal a piece of the puzzle in terms of how a cyclist’s performance is progressing and, as a near-universal figure, it’s an easy metric to use across multiple training platforms.
However, it is unable to provide as much insight as some other methods (both lab- and field-based methods, including a critical power test) for riders who want to drill down into the specifics of their physiology and training data.
Authors
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