Four Models That Define Who Is Fit

The foundation of CrossFit is notable for a number of ground-breaking insights.
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the box crossfit general physical skills

If you’re a CrossFitter who hasn’t dug into the philosophy and the foundation of what’s behind the challenging workouts, I encourage you to. In fact, knowing the methodology only makes the results more valuable.

The foundation of CrossFit is notable for a number of ground-breaking insights — one of which is the clear definition of fitness that CrossFit proposes. Until its signature definition “work capacity across broad time and modal domains,” there wasn’t a sufficient definition in sports science. Not only has CrossFit proposed a concrete definition, but it also has four specific models that, in combination, determine the answer to the question, “Who is fit?”

Here are the four models:

1. 10 General Physical Skills. 

In conjunction with the creators of Dynamax medicine balls, the 10 general physical skills represent those characteristically unique physical attributes of human capacity. These are cardiovascular repertory endurance, stamina, flexibility, strength, speed, power, balance, coordination, accuracy and agility. The person who is more proficient across all 10 general physical skills is more fit than the person who is less proficient. Obtuse capacities like having a 1,200-pound back squat, for example, and a 14-minute mile time trial would be a liability in CrossFit’s definition of fitness.

2. The Hopper Model. 

A hopper is one of those round barrels with a handle on the side so that it can turn, mixing the contents (often tickets or lottery balls) for contest-like selection at random. The model goes on to say that one who is more successful than another opponent in a series of random physical tasks or contests drawn from the hopper is more fit.

3. Energy Systems. 

This model goes on to recognize three generally recognized energy systems. (Think of them as gears that tap into unique fuel sources.) Maximal efforts that can only be sustained from zero to 15 seconds is called the phosphagen system. An additional anaerobic system called the glycolytic system has slightly less powerful expressions of output and can be sustained for upward of a couple of minutes. Lastly, the anaerobic system, which runs from several minutes to infinity, is called the aerobic system. The model goes on to say that the fittest would display better competency across all three systems.

4. The Sickness, Wellness, Fitness Continuum. 

This model says that sickness and fitness are opposing states that can be measured by a number of objective statistics from body-fat percentage, HDL/LDL cholesterol, VO2 max (maximum oxygen uptake), etc. As a person improves these metrics, they move down the spectrum toward fitness and further away from sickness. Conversely, as someone becomes sicker, they become objectively less fit.

This complex system of overlapping fitness models provides a bulletproof view of who is fit and who is not. Don’t believe it? Try to find a chink in the armor of this logic.