You’ve been told you need to train 15, 18 or even 20 hours a week to qualify for the Ironman World Championships. You’ve been told that you had to want it so badly that you had to devote your entire life to it – let alone your family and professional commitments. And although yes, the task is titanic, think it twice. What if you could qualify for Kona by training only 12 hours a week, still be able to balance the work schedule and never overtrain? It’s true. Just take Ralf Schön.

If you’re a coach, imagine an athlete approaching your coaching services with the goal of becoming a stronger cyclist. Imagine also that this athlete is mentioning his speed as a benchmark of his fitness.


If you’re an athlete, imagine yourself being that athlete. You approach your coach and you use your latest time trial speed as a measure of your fitness.


Clearly, this approach does not work as speed is not a reliable metric for benchmarking your fitness: speed is influenced by too many aspects (road inclination, cross winds, front winds, gear, kit …) which are not reliable metrics to improve cycling fitness. 

A look beyond FTP

We used the “speed example” ad absurdum, of course, but only to give you a first important unit of comparison: as well as training with speed, training and using only your FTP or power output to benchmark and monitor your cycling fitness is NOT an effective way to improve your cycling fitness for real.

It works better than using speed, but it’s still a huge approximation and will not target your specific goals (whether racing in an Ironman or winning a sprint). FTP is an “all-rounder”; it works for everybody, but it doesn’t show you how power is composed nor does it allow you to extrapolate lower values like FatMax or higher values like VO2max. Contrary, it only allows you to determine one training intensity accurately: the intensity at the threshold power.

“In order to really understand how your power is composed you need to look beyond FTP and look inside your body and muscles”

To get a precise picture and understand your power for real – and to plan your training zones specifically so that you can really target your needed fitness goals – you need to understand how power is composed. In other words: you need to know what lies behind power and what produces the power inside your body and muscles.

A look inside your power file

Let’s look at the infographic below to explain why it’s important to look “inside” any power file. Take into consideration a generic “Day 1”, where you averaged 475 watts for 4 minutes (well, congratulations!). After that, let’s pretend you will follow a “specific” training regime for two or three months. Finally, there is another, generic “Day 2” – where you re-tested your fitness level and check how your performance has changed through the training period.

On this generic “Day 2” you also averaged 475 watts for 4 minutes (again, a great effort!). Does this mean that the training didn’t work? Of course not, as the devil is in the details, and metabolically speaking, the composition of these two power performances can be very different and can come from the three different energy systems in your muscles and in very different percentages.

Real World example of the same effort before and after a training block: the maximum power production for 4min didn't change. However the composition of the power differs significantly. On the far right: projection of the total maximum power if the known best training states of each power supply system would be combined by specific training.

Where the power is coming from

For example, on Day 1, your power could have come mostly from aerobic metabolism (413 watts, or 87%), and only 5% from glycolysis (27 watts) and 8% (35 watts) from the breakdown of creatine phosphate (a limited energy store in your muscles). On Day 2, after your training period, the power could have been composed in a very different way: aerobic energy contribution may have dropped to 396 watts of the total power output (or 83%). And even the percentages of glycolysis and the creatine phosphate systems could have been very different: the power derived from glycolysis (lactate production) may have risen to 52 watt (11%) and the power derived from creatine phosphate dropped to only 27 Watt (6%).  

When you look at the whole picture, you can find out that training actually affected your physiology. And that the three energy systems that compose your power output adapted through the training period – and each one of them went into another direction. However, if you only look at your power number (or FTP), you wouldn’t disclose how your power is composed.

Now, you may still think that the physiological changes don’t matter that much, because the total power for your 4-min effort didn’t change at all – and that, at the end of the day, is all it matters for you. Fair enough!

INSCYD methodology has been a part of Peters training since his times at Team Cannondale Pro Cycling.

Why the energy source matters

But let’s imagine that you’re actually able to understand and disclose the origin of those two different 475-watt efforts. This extra, but crucial, piece of information would allow you to understand which kind of adaptation the training regime should target for those two/three months.

Connecting your training program to the specific training adaptations your body has gone through in those months (and looking back at the program in light of the adaptations), allows you to understand how the training actually worked on your body. Through this process, not only you can gain more specific knowledge on the subject, but you’re also able to understand which specific training you need to carry out to: in our example increasing your glycolytic (anaerobic) power without lowering the aerobic power contribution or creatine phosphate stores.

“Once you connect your training programs to your training adaptations you can really understand how training is actually working and train in a very specific way”

And only once you’re able to acknowledge this, you’re then able to train in a true specific way and create a training program that targets the adaptation to match your individual goals. Which is fundamental for all your future goals and future programs.

By benchmarking your performance and monitoring your progress with INSCYD, you will disclose the origin of your power output. INSCYD is the number one choice of some of the best athletes to understand how power is actually composed. And, consequently, it can guide your training schedules and sessions in order to produce the correct physiological power you need to perform at your best for your specific goals.