How we use WKO4 to Improve Cycling Performance

WKO4 is a complex piece of software that allows me as a coach to analyse my athlete’s data in unprecedented detail. It uses a powerful mathematical model to calculate metrics that allow for much more accurate training, by giving an accurate estimation of your FTP as it changes over time as well as providing us with individualised training zones along with new ways to review data and track progress.

It’s easy for me to get caught up in the science and mathematics, so I’ll try to keep it simple to give you an idea of the benefits of training with us and how it can help develop you as an athlete.

Power Duration Curve

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This is the heart of WKO4, it takes data from millions of points over the last 90 days to give an estimation of how much power an athlete is capable of producing at different timeframes. Taking this example of my own sorry excuse for training in the previous 90 days, you can see two lines, the yellow line and the red curve.

The yellow line is my Mean Maximal Power, the maximum power I can hold for any duration, you can see some definite drops at points where you can see I haven’t given it any good data beyond that point until it meets the next drop, this is very common towards the end of the power duration curve.

The red line is the model that WKO4 has created, estimating what it believes I can achieve by filling in some of the blanks and looking at my physiology. You can see it doesn’t have much raw data (yellow) for between 15 minutes and 1 hour, but it looks at all the data I have given it and gives me the benefit of the doubt, if I were to do some hard riding in this time period it would give me a more accurate number, whether this lowers or raises my FTP is not important to me, the most important thing is ensuring my zones are correct so I’m training in the right zones and stimulating the right energy systems.

You can also see several white lines moving from left to right, these help give me a good idea of my strengths and weaknesses. It doesn’t even consider me to have a ‘recreational’ level sprint and I haven’t done any big power work in the last 90 days, however it classifies my 10-30 minute power as “excellent”. This does not compare my wattage to other riders, but rather looks at my W/KG, how many watts I can output for each kilogram of bodyweight. The curve clearly shows that my sprint power is a weakness, but I’m training for an Ironman, it’s not a limiter to my performance and my focus is elsewhere as a result.


This stands for modelled FTP, and gives you one of, if not the most accurate idea of what your FTP is. Many people believe FTP is the highest power you can hold for an hour, which has resulted in several slightly masochistic riders going out and riding as hard as they can for an hour to get their FTP number. The alternative to this is the vastly more popular 20 minute test which I have previously used, but moved away from in favour of using WKO4’s mFTP, there are two reasons for this.

Firstly the highest power you can hold for an hour is an over simplification which has taken root in road cycling at every level, however this is not an absolute value, and has only ever been described as an estimate, the definition of mFTP that exercise physiologists use is *deep breath*

“The maximum power you can hold in a quasi steady state without fatiguing”

This can range from approximately 30 minutes to 70 minutes and is expressed in WKO4 as TTE, or time to exhaustion. The eagle eyed among you may notice that my TTE is currently very low, which informs me this is a weakness and something I need to address.

The 20 minute test is also flawed in that it takes 95% of your 20 minute power and calls this your new FTP, however for many this isn’t the case. For 70% of athletes this may be accurate, however for 15% they may need to take 97% of that figure, and the other 15% may need 93%. mFTP removes the guesswork from FTP calculations as rather than looking at a singe data point (your highest 20 minute power value) it looks at millions of data points from all of your riding to calculate your mFTP.

The lack of formal testing will come as a welcome relief to many, including myself. I can’t think of any athlete who has ever come to me and relished in these 20 minute efforts, they tend to dread these tests and they result in long recovery periods as the athlete is totally cooked. Last year I worked with a very strong athlete who I helped qualify for the World Championships that I remember building himself up for a 20 minute FTP test. He had the goal of hitting a certain number, worked out what power he’d need to hold for the 20 minutes to achieve this figure and guess what? He hit that number. The figure was a good result, but could he have gone harder? Or was it only the target he had set himself that got him through the test to hit that number? There’s also the issue with pacing, it takes a number of tests to give you a true understanding of how hard you can push yourself in those 20 minutes.

That’s not to say that we don’t do any testing, like any mathematical model, the more data you feed it the better the data it outputs, for this reason we ask athletes to perform a series of tests to give us a baseline at the start of the year to give us accurate numbers. I am writing this in early January in the middle of testing myself, once the initial tests have been completed (5 minute, 20 minute, 1 minute and 15 seconds) we then look to maintain these values over the year, using charts such as this one to identify where we need to give the curve more information:

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The software is asking the athlete for more information at the 2 second, 52 second and 1:29 point to give it more information. Timing a 2 second test seems almost impossible, and a 1:30 test seems unnecessarily stressful to me, so in this situation I would give the athlete a 52 second test and leave it there, as the 1:30 and 2 second data points will populate themselves over time.


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This is short for individualised levels, and represents the training zones recommended by the WKO4 model for different intensities, taking into account each athlete’s individual characteristics.

If we take two athletes with an identical FTP, but one of them is focusing on sprint triathlons and the other on Ironman, they will have very different power duration curves. WKO4 takes this into account and ensures that each athlete is working at the correct intensity to provoke the desired training effect, as opposed to the one size fits all approach that is used by most others, including the primary TrainingPeaks website. To combat this I spend time every week updating athlete’s iLevels on TrainingPeaks to ensure they match those on WKO4.

Many of you will be familiar with terms such as “tempo” “sweetspot” and “threshold” but the exact meaning of these may be unfamiliar to you, for many they are simply terms used to express how hard they feel they are pushing. The traditional 5 power zones are active recovery, endurance, tempo, threshold and sprint, but with WKO4 these are expanded to include:

Zone 1: Active Recovery
0-56% of FTP

This is the zone you will find yourself in when resting between intervals or if things have gone wrong in a race (happens to the best of us!). In this zone you’re riding, but you’re not really generating much of a training effect, so we aim for at least zone 2 in our longer workouts.

Zone 2: Endurance
56-76% of FTP

As a triathlete this is where you will spend the vast majority of your time. It’s not exciting, it’s not sexy and it can be dull, but it’s necessary for a strong aerobic foundation that allows us to race harder for longer on the big day itself. This should feel manageable and you should be able to sustain it for at least 2.5 hours. You can never have enough base fitness, but once you are able to ride for several hours with minimal changes in your heart rate it’s time to develop our training. As you can see this is quite a large range of your FTP, meaning it is easier to sit in this zone than other, which is a good thing as you’ll be spending a lot of time here!

Zone 3: Tempo
76-88% of FTP

This zone is where things start to get serious, some athletes will be able to stay here for an hour or two, others for up to eight hours, it depends on how well trained you are and more importantly the type of training you have been doing. This is the zone in which very well trained athletes will spend the majority of their Ironman 70.3 bike leg. However just because you can ride 90KM at tempo doesn’t mean it should be your goal for the race, as you still need to be able to run off the bike.

Zone 4: Sweetspot
88-95% of FTP

This is a great zone to sit in if you’re looking to boost your FTP, as for many road cyclists a high FTP is a badge of honour, something for them to brag about at the cafe stop. However as triathletes we use our FTP to base our race efforts off of, and it is as important for us to extend the time we can spend at FTP as increasing the number itself. As a result we spend less time training at sweet spot than road cyclists, but it still makes a frequent occurrence in the build period.

Zone 5: FTP
95-105% of FTP

This is your threshold value, or thereabouts. Sitting in this zone hurts, and you won’t spend much time here, nor will we train here for extended periods very often as the fatigue accumulated is significant, sweet spot is a much more economical way of boosting our FTP and resistance to fatigue.

Zone 6: FTP/FRC

This is the crossover point between our threshold and FRC, more details below

Zone 7: FRC

Your Functional Reserve Capacity looks at the amount of energy you can create while working above threshold, which is traditionally anaerobically. This is of little interest to us as non drafting triathletes as we don’t need to sprint or attack on the bike, so we rarely train in this zone.

Zone 8: FRC/PMAX

This is the crossover point between our FRC and PMAX, more details below

Zone 9: PMAX

This is the absolute maximum, or neuromuscular power we can generate in one complete revolution of the crack arms. Generally speaking efforts in this zone last for less than 10 seconds, the only time we should be in this zone is during fitness testing or potentially for a couple of seconds if we launch a blistering attack in a draft legal race.


This is only scratching the surface of the capabilities of WKO4, I have been using the software myself for a year, experimenting with it and playing around with the charts myself before I gained the confidence to start applying it confidently to my athletes. While its primary function is allowing us to monitor, and develop bike power, it also looks at pedalling effectiveness, aerobic development, fatigue resistance, provides you with a season review, power balance, the list goes on and that only covers the cycling side of things, there are a huge number of graphs for running and swimming.

If you wish to learn more about how we implement WKO4 in our training programmes, E-mail for more information.


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