Why CrossFit Looks the Way It Does

CrossFit’s original goal sounds simple enough: build a fitness program that was broad, general, and inclusive — one whose specialty was not specializing.

Actually pulling that off was the hard part.

Greg Glassman has said that when he first started talking about the idea, people told him it couldn’t be done. His response was basically: good. That was enough reason to try.

And if you’ve ever wondered why CrossFit programming looks the way it does — why one day you’re squatting heavy, another day you’re running and doing pull-ups, and another day you’re learning a snatch — this is where it starts.

The Definition Nobody Really Understands

CrossFit’s original prescription is:

Constantly varied functional movements executed at high intensity.

It’s accurate. It’s precise. It also doesn’t mean much to someone who has never done CrossFit.

Glassman even says as much in the talk. If someone asks what CrossFit is, the better answer probably isn’t to recite the definition. It’s to show them a class.

Watch people lift, run, row, jump, pull themselves over a bar, and learn movements they couldn’t do a month ago. Then the definition starts to make a little more sense.

But if you actually do CrossFit, those words are worth understanding, because none of them are there by accident.

Variance: Why We Don’t Do the Same Thing Every Monday

Most fitness routines eventually become predictable. Monday is chest. Tuesday is back. Wednesday is legs. Or maybe you run the same routes every week, lift on the same days, and repeat the same basic pattern year after year.

The problem is that your routine doesn’t just tell us what you’re good at. It also tells us what you’re probably bad at.

Whatever is missing from your training becomes a blind spot. Never sprint? You probably won’t be very good at sprinting. Never lift heavy? Strength is eventually going to be a limitation. Always train strength and conditioning separately? The first time you have to use both at once, things can fall apart pretty quickly.

That’s the real argument for constant variance. It isn’t randomness for the sake of making workouts interesting, and it isn’t because CrossFit coaches get bored easily. The point is to keep your training broad enough that one fixed routine doesn’t quietly create a permanent weakness.

Glassman describes it as looking for “a pattern that has no pattern.” That’s a pretty good way to think about it.

Over time, you should be exposed to heavy days, light days, long workouts, short workouts, running, lifting, gymnastics, intervals, carries, jumps, pulls, presses, and combinations of all of them. Not because every possible movement is equally important, but because fitness should hold up when the situation changes.

Why Separating Everything Doesn’t Always Work

There’s another idea Glassman brings up here that still feels relevant. For a long time, fitness was often split into separate boxes: strength on certain days, endurance on other days, maybe bodybuilding mixed in somewhere.

The assumption was that if you developed each quality separately, they would automatically come together when you needed them. But that doesn’t always happen.

You can be good at deadlifting. You can be good at running. Then someone asks you to deadlift and immediately run, and suddenly both feel completely different.

That combination creates a new demand, and CrossFit trains that on purpose.

Real life and sport rarely ask for physical qualities one at a time. You may need strength while tired, coordination while breathing hard, or power after several minutes of work. Training those qualities together is part of what makes CrossFit different from simply doing a little lifting and a little cardio in the same week.

Intensity: It’s Not Just How Tired You Feel

Intensity might be the most misunderstood part of CrossFit. People hear “high intensity” and picture someone yelling through a set of squats or lying on the floor after a workout.

But that isn’t really what the word means here.

In CrossFit methodology, intensity is tied to power output.

Power has an actual formula:

Force × Distance ÷ Time

In simpler terms: how much did you move, how far did you move it, and how long did it take?

That gives us something objective. If you move the same load through the same distance in less time, power output goes up. If you do more work in the same amount of time, power output goes up.

That’s very different from saying, “That workout felt really hard.”

Why Heart Rate Isn’t the Whole Story

Heart rate can be useful. It can tell us how your body is responding to exercise, and it can be helpful for managing certain types of training.

But it isn’t the same thing as intensity.

Your heart rate can spike because you’re nervous, scared, overheated, or full of adrenaline. None of those things necessarily mean you’re producing more power.

That’s the distinction Glassman is making. If we know the load, the distance, and the time, we can actually measure work and power directly.

That’s one reason CrossFit has always cared about scores: times, rounds, reps, and loads.

Those numbers aren’t there just to make workouts competitive. They let you look back and see whether your capacity has actually changed.

Did you do more work? Did you do it faster? Did you use more weight? Can you maintain the same output for longer?

Those are real signs of improvement.

Intensity Is Where Adaptation Happens

There’s also a more practical side to intensity. If you want your body to change, at some point you have to ask it to do something it isn’t already comfortable doing.

You want to get stronger? The load eventually has to increase. You want better conditioning? Your body has to learn to sustain more work. You want to become more powerful? You have to produce force faster. You want a movement to become easier? At some point you have to challenge your current capacity.

That doesn’t mean every workout should destroy you, and it definitely doesn’t mean intensity should come at the expense of good mechanics.

But there has to be enough challenge to give your body a reason to adapt.

That’s the part people sometimes want to skip. Hard training is uncomfortable.

Glassman makes that point in a much more colorful way:

“It’s why someone plays the tambourine rather than the violin.”

The point isn’t really about instruments. It’s that difficult things ask more of us, and fitness is no different.

Functional Movement: The Stuff Your Body Is Actually Built to Do

The last part of the definition is functional movement.

That phrase gets used everywhere now, often so loosely that it can mean almost anything. CrossFit uses it more specifically.

Functional movements are movements that are especially good at producing power. They allow us to move relatively large loads over meaningful distances, often quickly.

Think about a deadlift. You’re using your legs, hips, back, trunk, and grip together to pick something up from the ground.

That’s not just a gym movement. That’s a basic human task.

The same idea applies to squatting, carrying, pressing something overhead, climbing, jumping, running, pulling yourself up, or moving an object from the ground to your shoulders.

These movements show up because they reflect how the human body naturally gets work done.

Built Into Your Anatomy

Glassman gives a great thought experiment in the talk.

Imagine stripping the human body down to a basic schematic: bones, joints, levers, and major muscle groups.

Now ask: what is the most efficient way for that structure to pick something heavy up from the ground?

It’s going to look a lot like a deadlift.

What is the most efficient way to move something from the ground to the shoulders?

It’s going to look a lot like a clean.

These movements aren’t arbitrary exercises someone invented for the gym. They’re built around the way the body is designed to produce force.

Large muscle groups create force first, and that force is transferred outward through the body. That’s why so many functional movements are compound, multi-joint movements.

The body works together.

Why We Prioritize These Movements

Compare a deadlift or squat with something like a lateral raise.

A lateral raise can absolutely strengthen a muscle. There’s nothing inherently wrong with it.

But the load is relatively light, the movement is short, and there isn’t much potential to produce significant power.

Now look at squatting, deadlifting, cleaning, pressing, pulling, running, jumping, or carrying. More muscle is involved. More joints are involved. More force can be produced. More work can be accomplished.

That’s why those movements make up the foundation of CrossFit.

It doesn’t mean isolation work is useless. It means it’s usually the accessory, not the foundation.

Put It All Together

Now the original definition starts to sound a little less like fitness jargon.

Constantly varied — because we don’t want a fixed routine creating fixed weaknesses.

High intensity — because producing more work and more power is one of the major drivers of adaptation.

Functional movement — because compound human movements let us move meaningful loads efficiently and develop physical capacity that transfers beyond the gym.

Put those together and you get the logic behind a CrossFit class.

One day might be heavy squats. Another might be running and pull-ups. Another could involve Olympic lifting. Another might be a long conditioning workout.

The workouts change. The goal doesn’t.

We’re trying to build someone who is capable across a wide range of physical demands.

But What Does “Fit” Actually Mean?

And this is where Glassman’s talk gets more interesting.

It’s one thing to say CrossFit was designed to create broad, general, inclusive fitness. But that immediately creates another question:

What exactly is fitness?

Everyone uses the word. Athletes use it. Doctors use it. Coaches use it. The fitness industry definitely uses it.

But if we’re going to say our goal is to make someone more fit, we should probably be able to explain what that means.

And even more importantly, we should be able to measure whether it actually happened.

That was the next problem Glassman tried to solve.

His answer became three different models for understanding fitness — the 10 general physical skills, the hopper model, and the metabolic pathways.

That’s Part 2.

See the full lecture below: