Recently got a power meter, know you need to do an FTP test but don't know quite what that means? We explain Functional Threshold Power and its uses...

If you’re training for performance then the term FTP – which stands for Functional Threshold Power – will probably have come up at some point.

Measured in watts, FTP is the average power that a rider can produce over the course of an hour.

FTP is expressed in terms of watts per kilo – the power produced divided by the rider’s weight. It’s a nominal value based on the theory that you would need more power to go at the same speed, and less if you lose weight – even though taking slope, aerodynamics and rolling resistance into account that isn’t always the case.

Where once power meters were reserved for the pro peloton and very dedicated athletes, they’ve become much more popular in recent years and the arrival of smart turbo trainers has meant that even more riders have access to the magical world of wattdom.

Knowing how to train with a power meter is crucial to getting the most from one – and understanding FTP is pretty much the first step.

What does FTP tell you?

FTP is often used as the most accessible measure of fitness – when combined with weight and ideally heart rate data.

If you’re training for an event, you can measure FTP every four weeks to track progress. If the number goes up without your weight also increasing, you should have become fitter.

The ideal situation is that FTP has gone up, weight has gone down and heart rate to produce the same power is lower – but unless you’re starting from a fairly low level of fitness it would be incredibly hard to manage all three.

What are the limitations of FTP?

Whilst FTP is an effective measure of fitness, it lacks specificity.

A time trial rider trains their body to cope well with long, sustained efforts. A sprinter focuses on short, sharp accelerations.

The result is that if FTP is used as the only measure of fitness, then the tester will probably appear to be the ‘stronger’ rider on paper, but the sprinter has their own set of skills which certainly can’t be overlooked.

Time trial experts will have high FTPs – here’s Fabian Cancellara on his way to gold at the 2016 Olympic Games. Photo: Graham Watson

If you’re focusing on improving your sprinting, then it’s possible you might even lose a little fitness on the endurance side – but a dropped FTP would not represent a failure.

When testing FTP, therefore, it’s worth bearing in mind what you’ve been working on of late, and perhaps testing in conjunction with shorter efforts such as an all-out max five-second assessment.

Indoor training apps such as Zwift and TrainerRoad include FTP tests, which can be used to set intervals for training.

Going one better, The Sufferfest uses ‘4DimensionalPower’ (4DP), which looks at five-second, five-minute, 20-minute power as well as a one-minute effort following fatigue. The result is a picture of the rider’s Neuromuscular Power, Anaerobic Capacity, Maximal Aerobic Power and Functional Threshold Power. Looking at all of these figures each month would give an incredibly accurate representation of overall fitness.

How can you measure FTP?

There are several methods available.

The best option is to complete a time trial that will take about an hour – for example a 25-mile time trial. It’s much easier to get your best number when there’s another one pinned on your back.

Second best is to complete a one-hour criterium race and take the ‘normalised power’ number provided. Normalised power uses an algorithm to smooth out accelerations and is surprisingly accurate.

zwift

Zwift, TrainerRoad and The Sufferfest all have guided FTP tests you can take

Next, there’s the ‘FTP test’. The session given in Hunter Allen and Andrew Coggan’s book Training and Racing with a Power Meter may be growing in age (our edition dates back to 2010), but it’s still widely used and most training apps still stick with the protocol:

  • Warm up: 10 minutes spin then 3 x 1 minute fast cadence, 1 minute easy, 5 minute spin
  • 5 minute all out effort – go as hard as you can (press ‘Lap’ at start and finish)
  • 10 minute recovery
  • 20 minute all out effort (use that ‘Lap’ button again)
  • Cool down

Multiply the 20 minute effort by 0.95, to give you the number you’d get over an hour*.

*As a side note, personally I’ve always found that the number attained during the 20 minute indoor test, and my actual one hour performance in time trials outdoors, match up almost exactly. Perhaps it’s the effect of overheating indoors (even with a fan!), the lack of movement on a turbo, the ability to push harder in a race, or maybe even a bit of laziness. These are individual factors though – but certainly do not be surprised if your ‘indoor’ number is lower than your ‘outdoor’ number – this is very common – just make sure your expectations in training line up. 

How do you go about improving FTP?

You FTP will be used to set your training zones.

The exact percentages and training zones vary depending upon the coach that’s using them – but in ‘Training and Racing with a Power Meter’ Allen and Coggan promote those below:

Zone Percentage of FTP Use for
1 <55% Active recovery
2 56-75% Long, endurance rides
3 76-90% Tempo rides aimed at improving endurance at high effort
4 91-105% 8-30 mintue intervals focused on improving FTP
5 106-120% 3-8 minute ‘V02 max’ intervals
6 121-150% 30sec-3minute efforts focused on improving anaerobic capacity
7 N/A Efforts less than 30 seconds, sprinting, neuromuscular power

With these zones, you can establish which systems you want to target. Ideally, this will be periodised so you’re working on different attributes to suit your goals through the year.

If improving your FTP is a target, the something like this strength building block of 2×20 would be a good place to start.

There’s more indoor cycling sessions suggested here, with information on the target zones and what you’d expect to get out of them.

How ‘good’ is your FTP?

Firstly, the numbers vary depending upon the power meter used. Only very slightly, by a couple of per cent – but for that reason it’s not worth setting up bragging rights between you and your friends. Let your actual performance on the road do that.

If you’re desperate to know, however, then there are several handy readily available charts which show average ability across athletes when it comes to FTP, five minute, one minute and five second power output.

Checking out your performance across all four durations is a really good way of establishing your strengths and weaknesses as a rider. Almost essential if you want to compete in competitive events outside of the endurance realm of time trials.

The basic numbers for FTP – as listed by Allen and Coggan – look a bit like this:

World Class Pro Domestic Pro Cat 1 Cat 2 Cat 3 Cat 4 and 5
Male 5.6 – 6.4  w/kg 5.2 – 5.7  w/kg 4.6 – 5.3  w/kg 4.0 – 4.7 w/kg 3.4 – 4.1  w/kg 2.4 – 3.6  w/kg
Female 5.3 – 5.6  w/kg 4.5 – 5.2  w/kg 4.0 – 4.6  w/kg 3.5 – 4.1  w/kg 2.9 – 3.6  w/kg  2.0 – 3.1  w/kg

These numbers are based on the US system where categories start at five which is worth bearing in mind.