What Is Fitness? (Part 2

Adapted from Coach Glassman’s Feb 21, 2009, L1 lecture.

This concept started with me having what I call “a belief in fitness.”

I was (and still am) of the view that there is a physical capacity that would lend itself generally well to any and all contingencies—to the likely, to the unlikely, to the known, to the unknown. This physical capacity is different than the fitness required for sport. One of the things that demarcates sport is how much we know about the event’s physiological demands. Instead, we are chasing headlong this concept of fitness—as a broad, general and inclusive adaptive capacity—a fitness that would prepare you for the unknown and the unknowable.

And we went to the literature to look for such a definition and could not find anything. The information we did find seemed esoteric, irrelevant, or flawed— logically and/or scientifically. For example, to date the American College of Sports Medicine (ACSM) cannot give a scientific definition of fitness. They give a definition, but it contains nothing that can be measured. If it is not measurable, it is not a valid definition.

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The First Three Models And so we started playing with a definition and came out with three operational models. They were clumsy, but they had utility: They guided us and kept us on this path towards this fitness.

The first model originated from Jim Cawley and Bruce Evans of Dynamax medicine balls. They produced a list of physiological adaptations that represented the gamut of potential physiological adaptations in an exercise program. You can improve cardiorespiratory endurance, stamina, strength, flexibility, power, speed, coordination, accuracy, agility and balance by exercising. They gave reasonable definitions to each of these 10 so that they seemed fairly distinct. Keep in mind, however, nature has no obligation to recognize these distinctions. They are completely manmade. This model is an abstraction to help us understand fitness better.

What we did with this was we said that a person was as fit as he or she was developed in breadth and depth in those 10 capacities. And to the extent that he or she was deficient in one capacity relative to any cohort, he or she was less fit. This is a balance: a compromise of physiological adaptation.

The second model is a statistical model based on training modality. A hopper, like those used to determine a lottery winner, is loaded with as many skills and drills from as many different sports and strength and conditioning regimens imaginable. It could be agility drills from track; one-rep-max bench press from football; Fran, Helen and Diane from CrossFit; Pilates, and yoga. Do not exclude anything: the more, the better. Then, line up everyone willing to participate, turn the handle, pull a task out at random, and put them to the test. Here is the contention: he or she who performs best at these randomly assigned physical tasks is the fittest.

It may very well be that the fittest man on Earth is in the 75th percentile for each event picked. In fact, being best at many things would tell me immediately that you are not as fit as you could be.

For instance, if you have a 4-minute mile time, thousands of people are much fitter than you. Part of the adaptation to get a 4-minute mile is that it coincides with the max bench press of about half body weight and a vertical leap of 3 to 4 inches. That is part and parcel of the adaptation. It is not a character flaw. There is no value judgment. Rather, you are not advancing your fitness. Instead, you are advancing a very narrow bandwidth of a specialized capacity.

Everyone probably knows what it is he or she does not want to see come out of the hopper. What I have learned about fitness, about sport training, about preparing yourself for the unknown and the unknowable is this: There is more traction, more advantage, more opportunity in pursuing headlong that event or skill that you do not want to see come out of the hopper than putting more time into the ones where you already excel. That thing you do not want to see come out of the hopper “Valid criticisms of a fitness program need to speak to measurable, observable, repeatable data. If an alternative to CrossFit is worthy of our consideration it ought to be presented in terms of distance, time, load, velocity, work and power related to movements, skills, and drills. Give me performance data. CrossFit can be scientifically and logically evaluated only on these terms.”

—COACH GLASSMAN

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is a chink in your armor. It is a glaring deficiency in your general physical preparedness (GPP). And fixing it will give advantage where it does not always make sense maybe mechanically or metabolically.

We have countless examples of this from amateur and professional sports. At the heart of this is that we have learned some things about GPP that the world never knew before. There is more opportunity of advancing athletic performance via advancing GPP than there is in more sport-specific strength and conditioning training. For example, I am not sure why more pull-ups make for better skiers, but they do. We have some theories why that occurs, but we do not actually need to know the mechanism. We are focused on advancing performance.

So the second model is a statistical model using skills and drills. I am looking for a balance of capacity across training modalities.

The third model uses the three metabolic pathways. These are the three engines that produce adenosine triphosphate (ATP), the currency of effort of all energy output. Power is plotted on the Y-axis and duration of effort (time) on the X-axis. The first pathway (phosphagen or phosphocreatine) is high powered and short duration. It can account for about 100 percent of max human output and taps out at about 10 seconds. The second pathway (lactate or glycolytic) is moderate powered, moderate duration. It accounts for approximately 70 percent of max power output, peaks at about 60 seconds and terminates at 120 seconds. The third pathway (oxidative or aerobic) is low powered, long duration. It accounts for approximately 40 percent of max power output and does not fade in any reasonable time for which I have the patience to measure. The phosphagen and the glycolytic pathways are anaerobic; oxidative is aerobic. All three engines work all the time to some extent. The degree to which each is active is dependent on the activity. One idles, while the other two rev; two will rev, one will idle, etc.

Our thought is this: He or she is as fit as he or she is balanced in capacity in all three of these engines. A human being is a vehicle with three engines. Suppose we discover there is a fourth engine; we want capacity there, too. We develop capacity in all engines through our prescription: constantly varied functional movement executed at high intensity. We are looking for a balance in the bioenergetics (the engines that fuel all human activity).

Definition of Fitness (2002-2008) Although clumsy, these three models served as a litmus test for the fitness we were after. And we moved forward. We launched CrossFit.com and posted the Workout of the Day (WOD): constantly varied, high-intensity functional movement.

We were collecting the data from doing WODs and started asking: “What does it really mean to do Fran? What does it really mean to do Helen? What does it mean

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Table 1. Example Work and Power Calculations Between Benchmark Attempts

Workout Fran 21-15-9 Thrusters, 95 lb. Pull-ups

Athlete 6 ft. tall 200 lb.

Work Per Rep Force x Distance = Work (approx.)

Pull-up 200 lb. 24 in. x 1 ft. 12 in. 400 ft.-lb.

Thruster (athlete)

Thruster (barbell)

TOTAL 200 lb.

95 lb. 26 in. x 1 ft. 12 in.

47 in. x 1 ft. 12 in. 433 ft.-lb.

372 ft.-lb.

1,205 ft.-lb.

Per Fran Reps x Work = Total (approx.)

45 1,205 ft.-lb. 54,225 ft.-lb.

Power Date Finished Time Power Output (approx.)

April 2015 4 min. 30 sec.

May 2016 2 min. 45 sec. 54,225 ft.-lb. / 4.5 min. = 12,050 ft.-lb. / min.

54,225 ft.-lb. / 2.75 min. = 19,718 ft.-lb. / min.

Change in Power April 2015 May 2016 Change (approx.)

Power 12,050 ft.-lb. / min. vs. 19,718 ft.-lb. / min. 60% increase in power

Time 4.5 min. vs. 2.75 min. 60% decrease in time

Conclusion Time approximates our change in power output.

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to say that your time went from 7 minutes to 6 minutes to 5 minutes to 4 minutes?” Some interesting things came of this.

The workout Fran is 21-15-9 thrusters (95 lb.) and pull-ups. Complete the workout by doing 21 thrusters (front squat 95 lb., then drive it overhead), then 21 pull-ups (get your chin over a bar from a hang anyhow). Then go back to the thrusters for 15 repetitions, 15 pull-ups, 9 of each, stop the clock, and we get a total time for the effort.

Power is force times distance (work) divided by time. The work required to do Fran is constant (force times distance). It does not change unless your height changes (distance), the distance we travel (the movement’s range of motion) changes, the load changes (95 lb.), or your weight changes. This means that every time you do Fran or a specific benchmark workout, the work is constant.

So, you do Fran for the first time and have a Time 1 for it (T1). If you do it a year later, the same work was completed but you have a separate time (T2). In comparing the two efforts, we find that the work quantity cancels and the difference in time is the difference in power produced (Table 1).

There will be measurement error in this calculation. I can measure the force/weight with a scale, the distance traveled with a tape measure, and time with a watch. There is not a lot of error therein, but there are some concerns as we are calculating the body’s displacement by using the center of mass, for example. However, as long as the work is constant, the same error occurs with every effort. And in comparison from one effort to the next, the errors cancel each other out (zero order error). This ratio of time (T2/T1) describes my progress to the accuracy and precision of the watch, which is the best of my three tools (stopwatch, tape measure, scale).

By tracking the difference in time between workout attempts, we are looking at changes in power. We did not have to study this much longer to come to this understanding that your collection of workout data points represented your work capacity across broad time and modal domains. This is your fitness.

With power on the Y-axis and duration of effort on the X-axis, the power output of any effort can be plotted. Take a handful of efforts that take approximately 10 seconds to do, measure their power output individually, and then get an average of these efforts. Repeat this exercise at 30 seconds, 2 minutes, 10 minutes, 60 minutes, etc. Plot these data points. With adequate scientific accuracy and precision, I have graphed mathematically an individual’s work capacity across broad time and modal domains (Figure 1).

A Fourth Model and the Definition of Health (2008) Along the way in using these three models, we had also observed that there was a continuum of measures from sickness to wellness to fitness. If it was a measure I

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Figure 1. A Graphical Representation of One’s Fitness (Work Capacity) at a Certain Time in His or Her Life.

could quantify, something of interest to a physician or exercise physiologist, we find it would sit well ordered on this pattern.

Take body fat, for example. If you are 40 percent body fat, that is considered morbidly obese. The numbers vary by community, but 15 percent is often considered well or normal. Five percent is typically what you would see in an elite athlete. Bone density follows a similar pattern. There is a level of bone density that is pathological; it is osteoporosis or osteopenia in early stages. There is a value that is normal. We find gymnasts with three to five times normal bone density. I can do this with a resting heart rate, flexibility (any of the 10 general physical skills), and even some subjective things to which we cannot put numbers through analytical methods (e.g., mood). I do not know of a metric that runs counter to this pattern. This observation led us to believe that fitness and health were varying different measures of the same reality.

This also means that if you are fit, you first have to become well to become pathologically sick. It tells me that fitness is a hedge against sickness, with wellness as an intermediate value.

If there is anything in your lifestyle, training regimen or recreational pursuits that has one of these metrics moving in a wrong direction, I want you to entertain the possibility you are doing something profoundly wrong. What we find is when you do CrossFit (constantly varied, high-intensity functional movements), eat meat and

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Figure 2. A Graphical Representation of One’s Health (Fitness Throughout His or Her Life).

vegetables, nuts and seeds, some fruit, little starch, no sugar, and get plenty of sleep every night, we do not have this divergent side effect. It does not work such that everything is improving except one value. We knew this observation could be another test in assessing one’s fitness regimen.

Recall that we represent fitness as the area under the curve on a graph with power on the Y-axis and duration of effort on the X-axis. By adding a third dimension, age, on the Z-axis and extending the fitness across, it produces a three-dimensional solid (Figure 2). That is health. And with this measure, I have the same relationship to things that seemingly matter: high-density lipoproteins (HDL), triglycerides, heart rate, anything that the doctor would tell you is important.

I am of the opinion that health would be maximally held by maximizing your area under the curve and holding that work capacity for as long as you can. In other words: Eat meat and vegetables, nuts and seeds, some fruit, little starch, no sugar; do constantly varied high-intensity exercise; learn and play new sports throughout your life. This will buy you more health than will trying to fix your cholesterol or bone density with a pharmaceutical intervention. That it is a failed approach.

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I want you to understand how these definitions of fitness and health are different than those found in exercise-science literature. First, understand that our definitions of these quantities are measurable. One of the problems with exercise science is that it would very rarely meet the rigors of any real science (chemistry, physics, engineering).

Secondly, it is also almost never about exercise. For example, maximal oxygen consumption (VO2 max) and lactate threshold are correlates, maybe components, but absolutely subordinate to what happens to work capacity. Who would take an increase in VO2 max for a decrease in work capacity across broad time and modal domains? What that would look like is breathing more air than you ever had before on a treadmill test in a lab but losing the road race. Similarly, someone’s lactate threshold could increase, but he or she still gets choked out in the fight because of lack of work capacity.

I could make a list of hundreds of these metrics, and no one has ever produced a great athlete by advancing them one at a time. It does not happen. I can move them best by doing constantly varied, high-intensity functional movements; doing things that look like Fran, Diane, Helen; turning fitness into sport by working with fixed workloads and trying to minimize the time by making every workout a competitive effort among the cohort. And when I do that, what we find is that these metrics do spectacular things.

Suppose a man at 90 years old is living independently, running up and down the steps and playing with his grandchildren. We would not be concerned if his cholesterol numbers were “high.” There is a problem looking only at longevity. Imagine a curve that stretches to 90 or even 105 years but has very low work capacity for its duration. That is not what CrossFit is about: It is about vitality and capacity. What can you do?

It is imperative for making meaningful assertions about training that fitness and health are measurable. The area (or volume) under the curve gives me a scientifically accurate, precise and valid measure of an athlete’s fitness (or health). And we are the first to have ever done that. When we showed this to physicists, chemists, engineers, they agreed there is no other way to assess the capacity of something, be it a rocket, motorcycle, truck or human. Tell me how much it weighs, how far it moves and how long it takes. Everything else is entirely irrelevant.

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