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How to Determine an Athlete’s Fitness Level

Fitness (CTL): the metric

How to Determine the "CURRENT" State of an Athlete's Fitness Level?

When we begin to train an individual, the first question every coach asks is: what is your fitness level?

Perhaps this may sound like a silly question, but if we stop to think about it, we will see that the answer is not so obvious to what we imagine.  

Have you ever wondered how we determined an athlete’s fitness level?

And if there were a single number that would determine our level of conditioning, would not it be much easier?

Exercise physiologists generally agree that there are only three things you can improve to become physiologically more fit for endurance sports performance: aerobic capacity, lactate threshold and economy. Ultimately, these are the reasons you train … All this seems to tell us something, but at the same time they do not say what we really should know. 

fitness test on laboratory
vo2max as an fitness measure

Well, as we all know, there are genetic factors that contribute to our Vo2max. However, this does not mean that an athlete with a higher value of Vo2max will beat another athlete with less value.
For this will be influenced by the racing economy, how long the athlete manages to keep his effort at more intense levels. And most of all, at what speed it maintains its these levels of intensity.

Physiological Fitness

Let's understand how to get the variables that will define our fitness state.


SAID Principle & fitness

The  purpose of training is to physically challenge the body. From this challenge the body adapts and becomes more capable of handling a given level of stress. And to be effective, the training should be specific to the stress anticipated in the goal event for which you are training.

Therefore, Specific Adaptation to Imposed Demands (SAID) is associated with  “fitness.” 

Each athlete is equally fit for the unique physical demands of their sports. For example, if you want to define fitness as the physical skill required to hit a ball a long way accurately with a stick then the golfer is the fittest. 

                                                            (Joe Friel)


Fatigue is a product of Stress

From the moment you promote stress, at the same time you will be unbalancing your body at the muscular, chemical and physiological level. And as a result, we can sum to the term fatigue.

Fatigue is the product of stress. 

There is a very strong link between fitness and fatigue. If you are fatigued from training, then you stressed the body adequately enough to create the potential for fitness. So, when fatigue is rising you can expect the same thing from fitness. The opposite is also true.                                                                (Joe Friel)



Then we got to the point of competing. In order to race well one must reduce fatigue. This is what tapering before a big race is all about. You don’t want to go into important races tired. 

 Reducing fatigue is called “coming into form.”

Coming into form requires losing fitness. You must give up some fitness in order to shed fatigue and therefore race at the highest levels. Peaking is as much an art as a science. That’s because we are humans and not machines. There are many variables in our lives. 

                                                            (Joe Friel)

Doing the Math...

And what is the unit of measure to reach the magic number?

training stress

This may be the best definition of an athlete’s training load today. Through this parameter, called TSS (Training Stress Score), we can represent, through a single value, the relationship between the athlete and his workload.

Training Stress Score® (TSS)

Part #04

Training Stress Score®

Check out the Complete Sequence on Learning Category

sculpture shaping himself

Part #01

Training Variables

training intensity

Part #02

Intensity in Training and its Measures

Fitness (CTL): the metric

Part #03

How to Determine an Athlete's Fitness Level

training stress

Part #04

Training Stress Score

Performance management chart

Part #05

Performance Management Chart

Advanced metrics for training peaks

Part #06

Advanced Metrics on Training Peaks