What is fitness?
According to Training Peaks "Fitness is an exponentially weighted average of your last 42 days of training stress scores "
I doubt that any of you start on your fitness journey with that particular definition in mind!
Fitness is a term that means different things to different people, but for many of you I would imagine that fitness is about improving your bodily condition to become more physically fit and healthy, or to be able to complete a particular physical challenge.....
Fitness models such as Training Peaks are simply mathematical models of athletic training and performance. Mathematical modelling of training and performance is based on two concepts: The Critical Power Model which describes work rate over time, and the Banister Impulse Response Model which describes the dynamics by which your performance capacity changes over time as a function of training.
As coaches, whatever model we use, even if that is no model, it all comes down to 'Exercise Prescription'. The aim is to improve an individual's functional capacity, or fitness, to achieve improved health and general or specific athletic goals.
There is plenty of scientific literature on these subjects aiming to provide evidence based research for coaches to use when planning training. Much of this literature and research has flaws that make even basic elements of training design, such as volume, intensity and periodisation, controversial.
Scientific literature and mathematical models fail to address the critical aspect of all training. Exercise prescription is a highly individual experiment that requires a coach and athlete to accept that the process is one of trial and error, at least in the infancy of the coach/athlete relationship.
The Training Peaks and WKO models we use are however very useful; They provide a framework for us to easily understand the main drivers of athletic performance - Fitness, Fatigue and Form. They are very useful tools for long term planning and workout design, as well providing immediate feedback that we use when communicating progress with our athletes. Using these tools we are able to systematise the trial and error process by which we explore what makes an athlete improve at the most appropriate rate with a suitable amount of training risk.
The singularly most obsessed over metric used by many people we see is 'Chronic Training Load' or CTL. CTL provides us with a number that is meant to quantify fitness. CTL is a mathematical calculation that uses an exponentially weighted average of your last 42 days training stress scores. In simple language it looks at the workouts and rides you have completed over the last six weeks, works out the load over that time and assigns a fitness score.
When you start using Training Peaks, assuming you have no data to import, the model assigns you a CTL of zero! Now clearly you can see where the first hole in the model appears. No matter what you have done in the past I am pretty sure that everyone has some fitness 🤷♀️🤷🏻♂️ Over the next six weeks you feed the model data on your rides and workouts and hey presto you arrive at a point of realistic fitness estimation. If you have ridden at a moderate intensity and duration consistently over six weeks then your fitness score, or CTL, is likely to be around 40-50.
So what does this tell you?
It does not tell you that you are 50 times more fit than you were six weeks ago!
It does not tell you that you are half as fit as someone with a CTL of 100.
It does tell you have probably completed around 5 hours of moderate exercise over the last six weeks and have improved your fitness.
Fitness, whether you are using a model or not, can be built in vastly different ways.
Think of fitness as a cake 🧁 mix.
5 hours of moderate exercise a day will give you a tasty but plain sponge cake. 5 hours of high intensity interval training will give you a cake that is likely to be burnt. 5 hours of well organised, individualised and varied intensity training will give you a fantastic fruit cake that has an amazing depth and flavour.
This now begs the question...
"What do you want to go into your cake mix?'
It struck me a while ago that the way that many amateurs were training was just a watered down version of what the pros did, taking information from magazines and the like.
Why as an amateur rider would you want or need to train in any way like a pro? Are you going to ride the Tour de France? Are you going to be racing full gas every weekend at the Classics?
When you are thinking about what ingredients you want in your fitness cake you should think about what you want out of your fitness or what goals you are trying to achieve.
Clearly if you are racing or have signed up for an extremely challenging endurance event, then you will need to develop specific fitness abilities, and time them so that you are on your best form on race day.
However, for many riders what they really want, is to have good fitness all year round and to make improvements over time. For these riders, following a watered down 'pro like' training plan is not going to be very effective. A traditional linear periodisation will result in the detraining of several fitness abilities in the initial phases.
Many people would love to be strong, versatile riders with 3-4watts/kg power at threshold, the ability to punch the power up short climbs, to beat their mates in a sprint to the village sign and be able to ride for 3-4 hours without stressing about it. Designing a plan to fulfil these objectives would require looking back at their training history, completing an assessment of their current strengths and weaknesses, gaining an understanding of their work and family life and the time available to ride their bike.
Throwing all this into the cake mix we arrive at a fruity little number with many ingredients!
Knowing the ingredients is a good start. Now we have to consider the recipe. What quantity of each ingredient do we add? At what stage do we add it? How long do we mix each ingredient together for? Do some ingredients taste better when added at the same time?
All of this is what we coaches consider when we design your training plan and build your fitness. Chronic Training Load is a useful metric if, and only if, you have built the fitness in an appropriate way, firmly rooted in what your overal or specific goal is. If all you want is to develop the ability to ride long and easy, then a sponge cake of long rides will suffice. If however you want versatility then the ingredients have to be more diverse and mixed in an appropriate way.
Our overriding message is don't obsess about the numbers. Obsess over whether your training matches the outcomes you are seeking - does your training lead you down the path to you goals?
Now we have laid our stall out about how we think about fitness, next week we will talk about the absolute level of fitness or CTL you need and should strive for.
Good riding everyone this weekend. It looks to be a good one 😎
Rob Wakefield /
Founder & Coach