Varied, Not Random

If you've been in the gym for more than a few weeks, you've probably heard Rebecca and I talk about CrossFit's definition of fitness: constantly varied, functional movement, executed at relatively high intensity. Most people hear "constantly varied" and picture something close to chaos, a different workout every day so nothing ever gets stale. That's true on the surface, but it's not really what variance means to me when I sit down to write programming. Good programming works a lot like good science, in that it should be testable and repeatable: I should be able to point to an intention behind every workout and expect a fairly predictable result if I run that same kind of stimulus again down the road.

Most people gauge variety by soreness or post-workout fatigue, and it's an easy trap to fall into. Your legs are wrecked after a day of squats and lunges, your arms and back are toast after a day of pull ups and rowing, so it feels like the week must be balanced because different muscles are taking turns getting hammered. Soreness tells you which muscles worked, but it doesn't tell you how those muscles were asked to produce energy while they worked, and that second piece is where the real variety needs to happen. A short heavy set of squats and a 20-minute squat heavy metcon can both leave your legs sore the next day, but they are training completely different systems inside your body, and your legs adapt in very different ways depending on which one you're doing.

So, when I talk about variance, I'm not just thinking about which muscles get worked on a given day, I'm thinking about how your body is being asked to fuel those muscles, because that's the piece that actually determines what kind of fitness you're building. A lot of programming out there looks varied because the movements change from day to day. One day it's wall balls and burpees, the next it's rowing and box jumps. But if you zoom out and look at what those workouts are actually asking your body to do, they're often training the exact same system over and over again, just wearing a different outfit.

The three engines you're actually training

Your body has three main ways of producing energy, and each is trained by a different kind of effort. I think about all three when I am building out a week, not just the one that feels the most familiar.

The first is the phosphagen system, your instant power system. This is what you use for a max or near-max effort lift or an all-out sprint that lasts somewhere around eight to fifteen seconds. The catch is that to actually train this system, you need close to full recovery between efforts, something in the range of two to three minutes of rest (this may sound familiar if you've been in for squat days recently!!). A workout that's 15 minutes long or only has 0:30 of rest between sets is not going to meaningfully impact the phosphagen system, because no matter how heavy the barbell is, there just isn't enough rest built in for it to be the phosphagen system doing the work.

The second is the glycolytic system, which is the one most people associate with CrossFit because it produces that burning, gassed out feeling. This is where the classic 10-20 minute metcon lives. It's an effective and important system to train, but if every single workout falls into this window, you're really only building one gear, even if the movements change every day.

The third is the oxidative or aerobic system, and it's the one that gets skipped the most because it doesn't feel like training in the way people expect. This is lower intensity, longer duration work, often at a pace where you could hold a conversation or breathe through your nose the whole time. It doesn't feel impressive in the moment, but this aerobic base is the engine that everything else sits on top of. A stronger aerobic system means you recover faster between efforts in a metcon, and it means your body can clear the byproducts of harder efforts more efficiently. Skip this system and you're limiting the potential of your phosphagen and glycolytic systems and what they can do.

When I write a week, I'm asking a different question of your body on different days. Some days I want a raw, short, all-out effort. Some days I want the classic grindy metcon. And some days I want a longer, slower, aerobic piece that most people undervalue because it isn't flashy or doesn't make you collapse on the floor when you're done. All three are training you. None of them is filler.

Why workout length isn't random either

This is part of why you'll see a five-minute all-out piece on the board some days, and a 30-40+ minute aerobic session on others, instead of everything landing in that same 15–20-minute window every time. If every workout in a program runs the same length, that program is really just training one energy system in a lot of different costumes. If every workout leaves you in a puddle on the floor, you might feel like you're putting in your best effort or getting the most out of your program, but really, you're leaving massive gains on the table.

If it works, you can prove it

Here's the part I think matters most, and it's the part that's easiest to skip. Anyone can write a program that sounds good on paper, looks like fun, or has lots of variety. The way you actually know if it's working is by testing it, tracking the results, and testing it again down the road.

That's why there are benchmark workouts and retest cycles in our programming, and why your coaches are always asking you to get your scores tracked. When I design an eight-week block, I'm not just hoping it builds your aerobic base or your deadlift, I want to actually measure it before and after. If your numbers improve, that program did its job. If they don't, that tells me just as much, and I adjust. Tracking your workouts and taking retests seriously isn't busy work or just for the people who are “competitive”. It's the feedback loop that turns programming from an educated guess into something I can actually stand behind.

What this means for you

None of this is meant to turn every one of your workouts into a science lecture (but if you want one, ask, because I’m always down to get into the weeds!!). Most days you're just going to show up, listen to the workout brief, and get to work. But behind every one of those workouts is a reason it's programmed the way it is, on the day it's programmed, for the length that it's programmed. That's what I mean when I say varied, not random. The variety isn't there to keep things interesting for its own sake. It's there because your body needs different things on different days, and building real, lasting fitness means training all of it, not just the parts that feel the most satisfying in the moment.

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