Are FTP and Power Training Zones Different for Outdoor and Indoor Cycling?

Functional Threshold Power (FTP)

A survey found that about 80% of cyclists and triathletes complete at least one indoor cycling workout per week. The ratio of indoor to outdoor cycling workouts varies throughout the year, depending on the weather and how much daylight there is. We have noted that more athletes are using indoor cycling as a year-round training component than before. This leads to many questions about the real and perceived differences between indoor and outdoor Functional Threshold Power (FTP) and power training zones.

If you are training indoors and outdoors, you will need to use different FTP values, and therefore different power training intensity ranges.

What Is Cycling FTP?

At what intensity does the accumulation of lactate exceed its removal, resulting in a decrease in muscle force production? FTP, or lactate threshold, is the maximum amount of power a cyclist can produce for an extended period, usually an hour.

The build-up of lactic acid in the body is what causes fatigue in athletes, including cyclists. The body starts to supply energy through anaerobic pathways, known as the anaerobic glycolysis system when the demands of the activity are too high to sustain using aerobic energy production.

Lactate is the by-product of pyruvate acid. Pyruvate acid transforms into lactate when there is too much of it. If the body produces too much lactate, it will experience muscle fatigue.

Here’s the thing…

The only way to reduce the amount of lactate that builds up in your body is to train your body to become more tolerant of lactate. Essentially, what you need to do is train your body to better handle lactate. The more your body can handle, the more endurance you will have.

Despite what many cyclists think, high lactate thresholds are more important to improved endurance than maximal oxygen uptake.

Lactate accumulation is one of the main factors that contribute to fatigue. However, it can be trained to a certain extent to help improve race performance.

A higher FTP will lead to better endurance for a cyclist.

Testing Your FTP

Now that you have a basic understanding of lactate threshold or FTP, let’s explore two different approaches to assessing your FTP. Each FTP assessment method provides a moderate to accurate FTP value when performed correctly and with precision.

It is important to use a power meter for the most accurate results. While it’s important not to stress, an estimate of your lactate training zone is approximately 85% of your maximum heart rate. To calculate your MHR, simply find your MHR recorded from a sprint finish of a race. This equation provides a mostly accurate evaluation of the maximum heart rate for a vast majority of the population.

Conducting the FTP test can be done either indoors. Many cyclists commonly opt to test their FTP on a hill with a slight gradient to add an element of intensity for a more even power output.

60-Minute FTP Test

This is a test to see how much power you can sustain for 60 minutes. The rider must start at a self-selected pace and maintain that pace for the full 60 minutes. To complete the 60-minute FTP test, you must ride on a flat course at a consistent pace for the full 60 minutes.


FTP, or the cycling power output value sustained for 60 minutes, is the most accurate way to measure a cyclist’s performance.


Although the 60-minute FTP test is accurate, it can be too demanding for some cyclists, both mentally and physically. Most cyclists would not be able to sustain that level of power for that length of time, so the test may not give an accurate measure for them.

20-Minute FTP Test

A 20-minute FTP test is a variation of the 60-minute FTP test that only requires a person to sustain a maximal power output for 20 minutes. The mean power output is represented at 95% of the power sustained for the 20-minute duration to provide an equivalent ’60-minute FTP’ value.


This text is saying that the 20-minute FTP test is a better option for trained amateur cyclists than the 60-minute FTP test. The 20-minute test is less intimidating and requires less physical effort. The FTP test is relatively short, reliable, and can be done on an indoor trainer regularly.


The 20-minute FTP test is not as hard as the traditional 60-minute FTP test, but it is still a tough test that requires a lot of focus and even pacing.

Indoor vs. Outdoor Functional Threshold Power

An FTP value from an outdoor test is typically higher than an indoor FTP value. If you’re used to completing FTP efforts outdoors, you may find it more difficult than expected to do the same thing indoors.

If you can complete 36 minutes of endurance at 265 watts and an RPE of 7/10, and then you move your workout indoors and do the same amount of work, it will feel like an 8 or 9 out of 10. Instead of feeling sustainable, the intervals feel like a race-pace time trial.

Same Fitness, Different Performance

Functional Threshold Power is a measure of the maximum power you can output while pedalling. Your fitness is determined by how your body physically responds to training. The amount of oxygen you can deliver to working muscles and the capacity of mitochondria to break down fuel to usable energy is the same whether you ride inside or outside. Your performance can be impacted by several different factors depending on whether you’re inside or outside. Things like the weather and your equipment can have a big influence on how well you do. This is the reason there is no one-size-fits-all conversion factor between indoor and outdoor training ranges.

While it may not feel like it, indoor efforts tend to be more difficult than outdoor efforts at the same power output. Some athletes seem to be equally strong indoors as they are outdoors. Some athletes even ride better inside than outside. The amount of time you spend in each environment is often the deciding factor.

Is FTP different for indoor and outdoor cycling?

You can have different training zones for outdoor and indoor workouts, but it’s not necessary. The differences between the two aren’t usually that big. You should not use lab tests or field tests to identify a particular power output. Instead, they should be used to create training zones. The range of training intensities often differs by 5% or more of your FTP test result, regardless of which protocol you use. The typical difference between indoor and outdoor performance can be accommodated within specified ranges. This assumes that your FTP and training ranges are up to date.

For many athletes, there is not much difference between completing a workout indoors or outdoors. The target range is small. Just because you complete the task at the upper limit doesn’t mean it’s any better than if you completed it at the lower limit. It’s important to remember that there is no definitive cutoff point at which an interval becomes valueless. The cutoff point for watts could be anywhere from 245 to 258.

In some cases, outside factors can have a big effect on how well a cyclist does, to the point where using the same FTP number changes what the training is supposed to achieve. In other words, we’re using power output to target specific physiologic stress.

If the amount of stress felt by a rider differs significantly when the watts are set at 265 indoors versus outdoors, then the rider is not achieving the same objective. We strive to close the gap between indoor and outdoor performances so that we don’t need different indoor and outdoor power ranges.

Factors Affecting Indoor vs. Outdoor Cycling Power Output

If you have the same physiology no matter where you are riding, what causes the differences in performance and perceived exertion? The answer may be in your head. It is important to consider whether it is possible or necessary to reduce the amount of variation between different things.

Fixed vs. Free Movement

Your movement while biking has a large impact on your power output. Your bike can sway from side to side when you’re riding it outdoors, which changes how your core, hips, and legs are aligned to the pedal. How much you sway while pedalling can be determined by how strong your core is, how stable your hips are, how you’re positioned on the bike, and how intense the pedal stroke is.

When you ride a bike indoors, the bike is usually in a more fixed position. Many indoor trainers and smart bikes have features that prevent side-to-side sway, but some allow for a small amount of movement. Riders with weaker abdominal and buttock muscles, as well as less stable hips, tend to sway more when riding outside. This often results in a decrease in power output for these athletes when competing indoors.

The ideal solution is to work on strengthening your core, glutes, and hip stabilizers. Doing this will improve performance both indoors and outdoors. Think about trainers or accessories that will let you move a bit while riding indoors.

Heat, Airflow, and Dehydration

Too much heat can negatively affect your endurance performance while cycling, so it’s important to stay cool. As your body temperature starts to increase, your power output will start to drop and motivation to continue decreases, which can lead to a genuinely reduced capacity to produce power if prolonged heat exposure leads to acute dehydration.

To combat the heat, be sure to use fans indoors and make sure to drink plenty of fluids during indoor workouts. You don’t need to consume calories during shorter workouts that last 60 to 75 minutes, but you should still drink fluids.

Equipment Differences and Calibration

Many riders use a power meter based on cranks or pedals during outdoor rides and an ergometer indoors. Even though manufacturers say their power measurements are accurate, athletes usually have different power outputs on different devices. If you are only using one power meter, it is more important to have consistency between sessions than to have absolute accuracy.

If you are going to use more than one power measuring device for your cycling training, it is important to run the calibration procedures on the devices regularly. You may notice that devices give different readings for heart rate and effort during exercise over time. Some coaches may choose one power meter as the standard and adjust the Training Stress Scores® of workouts done with the other power meter if the differences are significant.

Rider Position

If you change your bike fit, you will see a big difference in your power. The majority of athletes strive to maintain the same riding position whether they are outdoors or indoors because it is advantageous to do so. The position of the bike in a trainer can influence your posture on the bike, or how you move in comparison to the bike.

Screen position can also affect power output. Athletes often place screens showing Zwift, Trainerroad, etc. at a higher level than they would when riding outdoors, so they can see them more easily. This can change the rider’s head position, hand position, and trunk angle while riding.

If you plan on competing in outdoor events, try to practice in conditions that match as closely as possible to what you’ll face outdoors. Though aerodynamics might be important for real-world sports, they don’t matter for e-sports. If you only care about power output and/or comfort, you can adopt a cycling position that doesn’t worry about aerodynamics.

Motivational Cues

The difference in performance between indoor and outdoor cycling can be motivated by different cues. Some athletes find it difficult to recreate their outdoor performances indoors without the extra motivation that comes from riding outdoors.

Some indoor cyclists may find that there are fewer distractions inside, or that they can use apps with motivational features to help them stay on track.

The solution to this problem is to synchronize your workouts with the environment that is the most motivating to you. Many athletes choose to do different types of workouts depending on whether they are inside or outside.

The Key Takeaways

As an athlete, it does not matter if you ride indoors or outside, you are still the same. cardiorespiratory fitness is the difference between indoor and outdoor performances. The ability to access and use this fitness to produce power is what makes the difference. Other things being equal, you’ll usually do better with the tools you’re most familiar with. There will always be slight differences between your power output outdoors and indoors, but these don’t need to be taken into account when determining your FTP values or training ranges. Bigger differences can regularly be improved by dealing with outside restrictions that confine execution. If there is a big difference between indoor and outdoor ranges, it might be a good idea to have separate ranges for each.



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