What is Fitness?

I believe I’ve attempted to write about this in my own way once before, and I’m sure if I went back and read that I would cringe. I’m going to re-attempt to explain what fitness is in accordance with the definition CrossFit founder, Greg Glassman, came up with 20 some odd years ago but you would be much better off going back and reading his original article.

I don’t know about y’all, but I can vividly remember that epiphanic moment I had when I first realized that we as a society had not determined what fitness was. I’m sure if you are reading this thinking, “What’s he talking about? Of course we know what fitness is.” To which I counter: look no further than the American College of Sports Medicine’s definition of fitness. It’s changed over the years, but it used to be, “Having a sense of vitality and energy,” along with several other hundreds of words all of which had ZERO observable, measurable, and repeatable characteristics. 

Having energy makes you fit? So, a guy on meth is fit? Lets bring this to today even. Orange Theory. Their claim to fame is chasing max heart rate. Well, surprise, surprise – heart rate is not a measure of fitness. How so? Well, if someone tries to rob you at gun point, isn’t your heart rate going to go up? Are you getting fitter in that moment? No. 

Coach Greg Glassman knew improving our fitness was important and anything important had to be measured. So he came up with three tests, weak definitions, but adequate models to determine who is fittest. 

The first of which are the ten general physical skills: cardio respiratory endurance, stamina, strength, flexibility, power, speed, coordination, accuracy, agility, and balance. Coach Glassman determined that he or she who is fittest would be balanced across all ten. Simple. And a deficiency in any one of them would cause you to lose in an expression of that thing amongst your peers. 

The second is the hopper model. This is the assumption that he or she who is fittest would perform best on average on any physical test that would come out of the hopper. Come up with 10, 20, 30 random physical tests, and line people up and see who performs best on average. Throw in everything, don’t exclude anything. 1 rep max deadlift. 10k run. Triathlon. Fran. 1 rep max clean. Max handstand hold. Hell throw in a pilates routine if you can place a value on who performs best at it. The goal was to ensure we “punish the specialist”. 

The last model is the most sciency of the three. It was the study of bioenergetics. There are three major metabolic pathways. Basically there are three ways in which your body is going to produce energy to complete a physical task. The phosphocreatine pathway. This is any output lasting about 20 seconds or less. The glycolytic pathway. This is going for about 30 seconds to 5 minutes. And finally the oxidative pathway, which is inclusive of pretty much anything you could for 10 minutes or more without stopping. This is also the pathway where we spend the most time. You’re actually in it right now as you read this. 

It was through these three models that Coach Glassman was able to develop an actual working definition of what fitness was, but much of what the program became was derived from these three tests. Someone who displayed capacity in all ten physical skills was able to perform the best on average at any physical challenge and displayed balance across all three metabolic pathways. 

The definition, still to my knowledge, is the only measurable, observable, repeatable definition in the fitness space: work capacity across broad times and modal domains. It is still the most effective way to make someone fitter. 


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