How to train with a power meter – part two: how to do an FTP test
Determining your training zones is the most important step when getting started with a power meter. Here's how to do it...
In the first part of this series, we looked at the benefits of training with a power meter. Now you’ve taken the plunge and have had a shiny new power meter fitted to your bike, it’s time to get out and use your new bit of kit to put yourself on the fast-track to becoming a better rider.
One of the best things about training with power is the ability to set accurate workouts specific to your goals – it’s undoubtedly the most efficient to ride train so you can achieve exactly what you want on the bike.
However, in you are working with a coach or even setting sessions for yourself, then you will need to know at what intensity you need to ride in order to bring about certain improvements in your fitness and form. This means training in a ‘zone’ – a concept which will inform almost everything you do when training with a power meter.
Doing an FTP test will hurt – but it’s a vital step when starting out with a power meter (Pic: Simon Wilkinson/SWPix.com)
However, before you can utilise your personal training zones, you need to first determine what they are and the best way to do this is to perform a Functional Threshold Power or FTP test.
There is some controversy around exactly what FTP represents, which we won’t get into here, but it is roughly equivalent to the power you can sustain for a prolonged period of time. That’s a bit vague, I know, however to give an example, on a great day you might be able to sustain your FTP power for almost an hour, or for a good time trialist might be your average power for a 25-mile TT.
In this article we’ll look at how to do an FTP test, key things to consider when doing a test and how to set your power zones based on the results.
What is an FTP test?
To do a FTP test properly you need to be fresh, so the first thing you need to do is to introduce a small taper in your training to ensure you are feeling good and motivated on test day.
While a maximum one-hour effort loosely defined as a rider’s Functional Threshold Power, going out and riding for as hard as you can for 60 minutes would be a very big effort and take a few days to recovery from.
If you were to do a one hour test, by the time you have tapered for a couple of days, then done the test and recovered for a couple of days afterwards, you wouldn’t get much training done at all that week – not ideal if you are looking to improve on the bike. On top of that, many riders will find it extremely hard to pace themselves over a one-hour test.
Therefore, we use a 20-minute test and take 95 per cent of the average power as a best guess of what you can sustain for a longer period, the idea being that if you rode five per cent easier you would be able to sustain that effort for a much longer period.
Doing a shorter test which takes less out of you means you can test and retest more often without missing too much training. Re-testing on a regular basis keeps your zones current and correct, and ensures you are getting the most out of your training at all times.
Your power zones will help you set accurate training sessions so you can achieve your goals quicker
The FTP test session
It’s important to start the session with a good warm-up and I have described a format below which you can use before any FTP, as well as before a time trial, criterium, cyclo-cross race or any other intense effort.
Then it’s time for the test – a 20-minute effort. The idea is to leave it all out on the road but try and ride as consistently as possible throughout. A perfectly-paced FTP test would results in a consistent output for 19 minutes, before a final sprint at the end where you get the last little bit of power out. At the end, you should be empty – but whatever you do, don’t set off too hard!
After the test you will need to take some time to cool down. Don’t stop straight away – instead, give yourself a minimum of ten minutes of gentle spinning to cool down and start the recovery process.
Five minutes in zone two* Eight minutes, riding progressively from zone two to zone four Two minutes easy spinning Five minutes in zone two, including 3×6-second sprints
Five minutes easy spinning
Twenty minutes – FTP test
Ten minutes cool down – gentle pedaling
* If this is your first time doing an FTP test you won’t have any power zones to follow in your warm-up, though if you have heart rate zones, you can substitute them in. If not, use can use the BORG RPE scale. This is a scale rating perceived effort from six to 20, with six representing sitting on the sofa and 20 going as hard as you can on the bike. In this case, zone two represents 12 on the BORG scale and zone four is 16-17. You can see the BORG RPE scale here.
A number of power zone models exist, but we will use the seven-zone model also used by Strava and Training Peaks
Key things to think about
Before you start an FTP session there are a few key things you need to think about.
First you need to decide where you are going to do the test. In an ideal world you would ride up a consistent 20-minute climb, however this just isn’t possible for most rider. Therefore, you need to try and avoid a couple of things.
Roundabouts, traffic lights or anything that might cause you to need to stop the effort. You need to be able to put out all your power for a full 20 minutes.
Tailwinds and descents. As you will quickly notice when you start riding with a power meter, it is very difficult to put out power when riding with a tailwind or downhill. No matter how hard you feel you are going, the watts are going to low for that effort. Try and avoid both tailwind sections and big descents for an FTP test.
Chances are that in the area you ride there won’t be a perfect piece of road to do a FTP test on. If that’s the case, you should pick the best bit of road you have and then always do your (re)tests on the same stretch. This way the effects of any small descents, corners, or anything else you need to slow down for are consistent in every test and, therefore, you can still compare one test to another across a season.
Your other option, which I will now look a in more detail, is to do your FTP test inside on the turbo trainer.
Indoor or outdoor?
At first, doing a FTP test on the turbo seems perfect – no roundabouts to get in the way, no descents to freewheel on, just you pedaling as hard as you can for 20 minutes.
Yes, this is a great way to get a 20-minute power test done but you can’t expect an FTP test on the turbo to give you the same numbers – and, therefore, the same zones – as an FTP test performed on the road.
There are two reasons for this. First, no two power meters measure exactly the same, so if your turbo trainer has a built-in power meter, like many modern smart trainers do, you can’t expect an FTP of 250 watts to be the same on your power meter on your bike as the one in your turbo. If you are going to do an FTP test on the turbo you need to measure it using the power meter you will use out on the road.
Secondly, the way you produce power on the turbo trainer is slightly different than out on the road. On the road there is far more variability because of all the externals factors: changes in road conditions, little undulations in the road, wind etc. You might not see these small changes in power output on your head unit but they are there.
Some riders will be able to produce more power on the turbo, others less – as a cycling coach, I have seen both cases. An FTP test on the turbo will give you a good baseline but it won’t be 100 per cent accurate for efforts on the road; likewise an FTP test on the road won’t be 100 per cent accurate on the turbo. For the best results, in the past I have asked coaching clients to do both indoor and outdoor tests, so they can then use the relevant zones depending on where they are training. Otherwise, choose based on where you will do most of your training.
Whether you do your FTP on the road or on a turbo trainer, it’s important to make sure your results are reliable and consistent
How to set your power zones
Once you have done your FTP test, it’s time to calculate your training zones.
Take your average power for 20 minutes (not your normalised power) and find 95 per cent of that number (multiply it by 0.95) – this is your FTP.
Now you have your FTP you can calculate your training zones. There are a number of different power zone models but here we will focus on the seven zone model used by Strava and Training Peaks.
Zone
Percentage of FTP power
Zone one – Recovery
<55%
Zone two – Endurance
55-75%
Zone three – Tempo
76-90%
Zone four – Threshold
91-105%
Zone five – Vo2 max
106-120%
Zone six – Anaerobic
121-150%
Zone seven – Neuromuscular
>150%
So there you have it – you have done your FTP test and now have power zones to use in your training sessions. In the next article, we will look at how to best use those zones in training.
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