Is FTP the best measure of cycling performance?
In this article Coach Alan looks at FTP – what is it, how can we use it and why FTP might be misleading your cycling training. Once we can understand all of that, we can better understand what we can do with this information and how you can inform your training.
First of all, let's look at what functional threshold power (or FTP) is and what it measures. FTP, in theory, is the amount of power, watts or work output that you can sustain for one hour. Being a measure of one hour means that this is an aerobic measure; as you can see in the graph below, anything lasting lower than a minute has a majority contribution from the oxidative or aerobic energy system. For endurance sports, this means that FTP is an excellent predictor of race performance. However, there are two other important questions to ask.
Energy Systems modelled on the Power (or Pace) - Duration Curve
ATP Stores - Orange (e.g. Weightlifting) | ATP-PC System - Purple (e.g. 100m Sprint) | Lactic Acid System - Green (e.g. 200m-400m Sprint) | Oxidative System - Blue (e.g. 800m+ Run) | Maximum Performance - Red
1. Is energy usage 100% aerobic?
As triathletes, we tend to compete in events of between 1 and 17 hours in duration. Based on the graph above, it is easy to assume that everything is aerobic, but it isn’t. The fastest way to finish a race in laboratory theory is to evenly pace or negative split your effort, but this is almost impossible to execute in real life. Out on the course, we have an acceleration phase at the start of the swim; we slow into buoys and accelerate again, we re-enter the water, we transition, we ride uphill, and into the wind, we pass groups. On the run, we take dead turns and climb hills again, all of which require subtle changes in effort.
Of course, the shorter the event, the more likely these subtle changes will become anaerobic. This is likely to be “normal” for draft-legal races, and for highly competitive age groupers and professionals, this would extend over the IRONMAN distance.
2. Do we only ever train our aerobic system?
The answer is not to train only our aerobic system. It is important not only to push up our thresholds by working just below them but also to go above them to lift them. To go fast over a longer duration, we first need the capacity to go faster over a shorter duration. Fundamentally this is how FTP works: for aerobic training, we take the FTP and work out zones based on a percentage of our FTP. Dr Andrew Coggan developed a seven zone system, as you can see below:
Zone 1 <55% FTP - Active Recovery
Zone 2 55-75% FTP - Endurance
Zone 3 76-87% FTP - Tempo
Zone 4 88-94% FTP - Sweetspot
Zone 5 95-105% FTP - Threshold
Zone 6 106-120% FTP - VO2Max
Zone 7 >120% FTP - Anaerobic Capacity
Zone 6 and 7 are of particular interest as we know that VO2Max and anaerobic capacity are not the same for all athletes. Furthermore, they are not the same for athletes with the same FTP. Critically, we are all different in our abilities above FTP. Therefore, when training above FTP, we will be training at a less precise level or zone if we base our training solely on a percentage of FTP.
FTP and aerobic zones will ensure that your endurance training is accurate, and for long-distance athletes, this will take you a very long way in your performance. Indeed, for developing athletes or those that have trained for the longer distance for a long time, simply working on doing ‘hard’ efforts will be very productive and help keep the main thing (aerobic endurance) the main thing.
So how can you train above FTP more accurately?
However, for high-performance athletes, short course athletes or those looking to squeeze out a little more from their training, we can use i-Levels, also developed by Dr Andrew Coggan. This different zones system exists in the custom analysis application called WKO. WKO is a powerful analytical engine that allows incredible flexibility to delve deep into data. It offers the next level of insight into an athletes strengths and weaknesses on the bike. It won’t make you faster if you can’t swim straight or corner effectively, but it can be very powerful.
iLevels is individualising your training for increased effectiveness. The model works on the different powers (mean maximal power) you can hold for all durations to mathematically feed a model that works with some new metrics that better describe the entire power duration, not just sub FTP. Crucially with this model, it is only as accurate as the data you feed it. In other words, if you never do max-efforts, your max power targets won’t be very high.
mFTP = Modelled FTP
FRC = Functional Reserve Capacity - better understood as the capacity of your anaerobic ‘battery’
Pmax = Maximal Power
These numbers make phenotyping a lot easier below. I have taken some screenshots of some of the athletes I work with and how their anaerobic ability varies. I have ranked them by absolute FTP, but as you can see, the other metrics differ considerably. The first two athletes are training for long course racing, and as such, their metrics look similar, with their FTP being their strongest area. This isn’t, however, true for the third athlete who is training predominantly for sprint distance racing and, as such, has a much better trained FRC and possibly trait FRC.
By understanding these differences above FTP, we are able to set individualised zones for athletes above FTP, giving them more precise targets when trying to develop their anaerobic capacity, VO2Max and ultimately FTP by working above them.
To demonstrate these differences, below are the FRC/FTP (VO2Max) targets for the three riders above, along with a comparison of what this looks like as a percentage of their mFTP:
Rider A = 253 - 348W (104.9 - 144.39%)
Rider B = 320 - 425W (105.2 - 139.80%)
Rider C = 356 - 533W (105 - 157%)
FRC, in particular, can also be beneficial in understanding how individuals might analyse their pacing may have been effective or ineffective for them as an individual, but more on that in a later blog. For now, start to consider how your anaerobic differences from other athletes. How might it influence your performance as well as your FTP?
Alan has worked with Tri Training Harder since 2014. During this time working with a wide spectrum of athletes from beginner, to youth and junior elite athletes through to 70.3 and Ironman AG winners and Ironman Kona Qualifiers.
An active Triathlon coach since 2007 Alan has been fortunate enough to work with athletes, peers and support staff who have continutally challenged him to evolve and develop. Building on a solid foundation in swimming teaching, Alan has specifically developed swimming coaching experience having worked in High Performance Swimming environments. Alan's other passion is all things fast on a bicycle!
Since 2015 Alan has worked in conjunction with the other Tri Training Harder Coaches to significantly develop collective coaching practice both on camp and online.
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