What Is Functional Threshold Power & Why Does It Matters for Cyclists?

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If you’ve ever spent time hanging around cycling circles or participating in group rides, there’s a good chance the term Functional Threshold Power has found its way into the conversation. Functional Threshold Power, or FTP, is one of the most common training metrics used in cycling. It’s also often a source of competition among riders. 

Functional Threshold Power is defined as the highest average power you can sustain for approximately an hour, measured in watts. Like with most things, there’s a lot more to FTP than just that.

In this article, we’ll dive deeper into Functional Threshold Power and explore why so many choose to measure it, how to determine your FTP, and what you can do to improve it. We’ll also discuss the drawbacks to FTP and whether it’s the best metric to use to steer your training. 

What is Functional Threshold Power?

Functional Threshold Power is the most common metric used to gauge a cyclist’s level of fitness. According to Dr. Andrew Coggan, physiologist, and developer of the Functional Threshold Power standard, FTP is “the highest power that a rider can maintain in a quasi-steady state without fatiguing for approximately one hour.” Put another way, it’s your power output at your lactate threshold.

When you exercise, your blood lactate level starts to rise. As the intensity of the exercise increases, your body will eventually hit a point where it can no longer clear the lactate as quickly as it’s being produced. This is your lactate threshold. When this happens while cycling, you go from being able to maintain a specific power output for a longer duration to only being able to endure it for a few minutes.

Your FTP is the gray area that represents this transition point in your body. It’s the maximum power or effort you can maintain while still allowing your body to clear the excess lactate produced by your working muscles.

Why Measure Functional Threshold Power?

Determine Your Training Zones

To improve cycling fitness, workouts should be optimized to your current fitness level. Training zones allow you and your coach to design training rides that provide the needed stimulus your body requires for adaptation. All of which leads to you becoming a faster and stronger cyclist. Because FTP is an objective measurement, it provides a solid benchmark for establishing power-based training zones.

ZoneNamePower (% of FTP)Heart Rate (% of threshold HR)Description
1Active Recovery< 55%< 68%Very low-intensity training (easy spinning or light pedal pressure) used for active recovery
2Endurance56 – 75%69 – 83%Long slow distance (LSD) training designed to improve cardiovascular endurance
3Tempo76 – 90%84 – 94%20 – 60 min intervals designed to improve muscular endurance; The typical “racing” zone
4Lactate Threshold91 – 105%95 – 105%10 – 30 min intervals just below to just above TT effort designed to improve lactate threshold
5VO2 Max106 – 120%> 106%3 – 8 min higher-intensity intervals designed to increase VO2 Max
6Anaerobic Capacity> 121%N/A30 sec – 3 min high-intensity intervals designed to increase anaerobic capacity
Source: TrainingPeaks

Utilize Other Training Metrics

For many coaches and athletes, FTP is the central metric used to analyze workouts and identify long-term trends. It also provides the foundation for other calculations such as Training Stress Score (measures how much stress a training ride had on your body), Intensity Factor (measures how hard a ride was in relation to your overall fitness), Chronic Training Load (measures stress over time), Form (measures how fitness and fatigue are balancing), and many others.

Measure Improvement

As you train, it can be easy to assume you’re getting fitter and faster. Improving your time on an interval, beating a friend up a hill, or simply feeling stronger on a training ride is all helpful information, but it doesn’t tell you definitively.

Although lab testing is the most accurate method for measuring improvement and trends in your cycling fitness, it’s not a realistic solution for most people. Regular assessment of your FTP is a more practical way to know whether your performance is improving.

Understand Your Capabilities

When training, and especially when racing, it can be easy to start out way too hard and then fade all the way to the end. Think of your energy tank as a book of matches. Once you use them, they’re gone. And if you burn through them too quickly, you won’t have anything left to help you finish. A big part of maximizing energy and effort is pacing. Having an accurate FTP will help you understand what your pacing should be for a specific ride and allow you to develop a plan for it. 

How Do You Measure Functional Threshold Power?

To measure your FTP, you need a power meter on your bike or one integrated into a smart trainer. When given the choice, riding your bike outdoors is best. This is because you’re typically able to generate more power when the bike isn’t fixed to a trainer.

As for how to measure your FTP, the most accurate way is to ride as hard as you can for one hour. Once finished, find your average power, and that’s your FTP. The problem with this method is it’s extremely difficult. Because of this, alternate methods have been developed.

20-Minute Test

The most commonly used method to measure FTP is the 20-minute test. The goal is to ride at an intensity that you can sustain throughout but also allows you to exert max effort. Once the test is completed, find your average power and multiply it by 0.95. That’s your FTP. The downside to this test is it can be difficult to pace properly.

8-Minute Test

The 8-minute test is more intense but easier to pace. Similar to the 20-minute, the goal is to ride as hard as you can for eight minutes without fluctuations. Rest for ten minutes and then repeat. Once complete, find your average power between the two efforts and multiply it by 0.90. That’s your FTP.

Ramp Test

The Ramp Test is best suited for smart trainers. Unlike the other tests, it’s a test to failure. After a brief warm-up, the test begins at 100 watts, then increases by 20 watts each minute until you can no longer maintain target power. Once the test is finished, take the best one-minute power achieved during the ramp portion and multiply it by 0.75. That’s your FTP.

Regardless of the method you choose, the key is to make sure it’s a method you can repeat in the future. This ensures you get consistent results from one test to the next.

What’s the Best Way to Compare Functional Threshold Power?

It’s natural to want to compare your FTP to that of other riders. However, comparing the raw number doesn’t paint a completely accurate picture. This is because it’s affected by a rider’s size and weight. Larger cyclists often produce more power than smaller riders because they have more mass they can use to generate force. But this doesn’t mean the larger cyclist is riding any faster.

To get a better feel for how your FTP compares to other riders, it’s recommended that you convert it to a power-to-weight ratio (PWR). To do so, divide your FTP by your weight in kilograms. For example, a 200-pound rider with an FTP of 250 would have a PWR of 2.76.

According to Dr. Coggan, PWR generally increases with fitness and experience. In his power profiling table, he shows that novice riders with a basic level of fitness will typically be around the 2.0 range, whereas world-class riders can be upwards of 6.0+. Although PWR has value and provides a way to see how you compare to other riders, it’s not something to obsess over or allow to impact your training.

How Do You Improve Functional Threshold Power?

Like with any fitness or performance goal in cycling, improving your FTP simply comes down to training. Although any workout above active recovery and below VO2 max will enhance muscular metabolic fitness, the biggest improvements come from training near or above your threshold. This means spending time riding in zones three and four.

Frank Overton, founder and head coach at FasCat Coaching, is a big proponent of “sweet spot” training as a way to increase FTP. The sweet spot is generally defined as the overlap between the top end of zone three and the low end of zone four. Although there’s no shortage of ways to design workouts that target the sweet spot, Overton recommends the following as a good starting point:

  • 4 x 15 minutes between 84% and 97% of FTP; 10 minutes of easy riding between efforts.
  • 2 x 20 minutes between 84% and 97% of FTP; five minutes of easy riding between efforts.

How Often Should You Test Functional Threshold Power?

The short answer is, as often as you think you’ve had a significant or meaningful change in fitness. Since FTP is used to determine training zones, it’s important to ensure those zones properly reflect your current level of fitness. Failing to do so can lead to not challenging yourself enough or, worse yet, pushing yourself too hard.

Generally speaking, if you’re new to cycling or jumping back in after a layoff, you’re going to experience improvements much faster. As a result, you’ll likely want to test more frequently. If you’re an experienced cyclist who has been training and competing for years, large gains are going to be fewer and farther between. So testing two to three times throughout the year may be more than sufficient.

What Are the Drawbacks of Functional Threshold Power?

Although FTP is the most commonly used metric in cycling, it’s important to note that it does have drawbacks. For one, it’s a snapshot of your fitness on a particular day. This means it can be easily affected by factors such as fatigue, stress, wind, how well the effort was paced, and so on. All of which can vary dramatically from one day to the next.

Another drawback is that most cyclists will choose to perform an abbreviated version of the test (such as the 20-minute test) instead of doing the full 60 minutes. This can lead to an overestimation of your FTP, causing you to train harder than you should for your current level of fitness.

Additionally, FTP isn’t appropriate for all cycling disciplines, such as endurance events or multi-day races. According to Dr. Stephen Seiler, Professor in Sports Science at the University of Agder, “It tells us something over a short period of time, but over a long period of time, the FTP power deteriorates. What is going on in their body after three or five hours? I want to know how durable your body is at low power and its ability to repeat high-intensity efforts over time.”

Although there are drawbacks, FTP has an important place in cycling. Even its detractors agree. Its convenience (you don’t need access to a lab for regular testing) and ability to be used across multiple training platforms make it a great tool for amateurs and coaches alike.

Frequently Asked Questions

What’s the difference between Functional Threshold Power and VO2 max?

Although FTP and VO2 max are both used to measure cycling performance, they represent different physiological characteristics. FTP is a measure of the highest power output a cyclist can sustain for an hour, while VO2 max represents the maximum amount of oxygen a cyclist can consume (or uptake) and utilize during exercise. Whereas VO2 max is just influenced by oxygen uptake, additional factors such as muscular endurance and anaerobic capacity also play a part in determining FTP. That said, both are important for understanding cycling performance and developing an appropriate training program.

What are some common mistakes to avoid when testing Functional Threshold Power?

FTP is a useful metric for measuring cycling performance, but only when accurately measured. Here are some common mistakes to avoid when performing an FTP test:

– Not maintaining a steady effort throughout the test. Either starting too hard and burning out before the end of the test or going out too slowly and surging near the end.
– Not warming up properly before the test.
– Failing to properly fuel prior to the test.
– Testing when exhausted or not recovered from a hard ride.

Can Functional Threshold Power be used for other sports besides cycling?

While FTP is primarily used for cycling, the concept of functional threshold power can be applied to other endurance sports, such as running and rowing, to help determine appropriate training intensities. However, the specific process for measuring and calculating FTP may differ.

Does cycling cadence impact Functional Threshold Power?

Since your cycling cadence directly influences the amount of force being applied to the pedals when riding, it can have a significant impact on your FTP. A higher cadence generally requires less force per pedal stroke, while a lower cadence requires more force. By finding an efficient cadence that doesn’t cause you to fatigue too quickly, you can sustain a higher power output for longer durations, thus maximizing your FTP.

Will getting a proper bike fit improve my Functional Threshold Power?

The goal of a proper bike fit is to place your body in the most efficient position while cycling. It ensures you’re able to efficiently transfer power from your legs to the pedals. Proper alignment of your hips, knees, and ankles reduces wasted energy and allows you to generate more power. All of which enhance your FTP and overall cycling performance.

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Hey there! I'm Michael, founder and chief editor of Bicycle Review Guru. I've been an endurance sports junkie the majority of my adult life and fell in love with the sport of cycling when training for my first Half Ironman triathlon over 10 years ago. My passion is sharing my knowledge and expertise to help you get the most out of your cycling journey.

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