High Intensity

Alrighty y’all. Here we are. The last post in a three-part series on the pillars of CrossFit. This one is going to get “intense” 😀

So what is intensity? As you all know by now, I’m a big fan of defining things. It may be an annoying quirk to some of you, but unless we define our terms, we can’t actually have a discussion. That is why I insist upon defining terms. If you want to talk to your friends about who the best quarterback of all time is or which of Taylor Swift’s albums is the best, you have to define what you mean by “best”. Is the best quarterback the guy with the most super bowls, most passing records, or the most wins? Is T-Swizzle’s best album the one that sold the most copies, had the most number 1 hits, or the one that helps you get over your break-up the easiest? It’s Red. Obviously. She was just so fierce on that album. My homemade chart that quantifies fierceness says so.

CrossFit defines intensity as power output. Plain and simple. If you remember from my last post on functional movements, Power = Force x Distance / Time. How heavy was the thing you moved, how far did you move it, and how long did it take you? If weight or distance go up or the time it took you goes down, you have increased your power output, and as a result, increased your intensity. This is obviously a more “scientific” definition of intensity but I think it does explain what is actually behind the physical feelings that most people would associate with intensity. “The suck” as we like to call it.

Fun side note: want to know the unit of measurement for power? Watts. Yeah. That NEVER got old in high school physics class.

I think CrossFit’s definition is the most complete one but let’s explore some others.

Heart Rate is often used to measure exercise intensity. That could work, but only on an individual basis. Two men who are the same age, height, weight, and have the exact same mile time probably don’t have the exact same max heart rate or the same responses to increased effort. So just measuring their heart rates won’t definitively tell you who is working harder. Plus, heart rate is subject to other factors like the state of your nervous system and stress levels.

A couple more limitations, and perhaps the biggest ones, of using heart rate to measure intensity are that it is difficult to infer progress and it doesn’t take broad types of movements into consideration.

How do we measure (physical) progress in CrossFit? If your weights are going up and your times are going down, you are getting fitter. Let’s say I did Open WOD 14.5 in 2014 and it took me 16:00. Let’s say my heart rate averaged 150 beats per minute (bpm). Now let’s say I did the workout again in 2018 and my time was 12:30. What if my heart rate averaged 150 bpm again? According to people who want you to measure heart rate and stay a certain “zone” for as long as you can, I would have actually done less for my health. My workout was almost 4 minutes shorter so I would be spending less time at that higher intensity. But according to CrossFit, I became fitter because I did the same amount of work in less time.

How about using broad types of movement? Isn’t that important to health? Yes it is, which is why the three pillars include “constantly varied” and “functional movement”. Can you reasonably measure exercise intensity on a stationary bike or treadmill? Yes. But is that all you plan on doing for exercise for the rest of your life? I hope not. Is your heart the only thing you want to stay operating optimally? I hope not. You have muscles, tendons, bones, nerves, and a lot of other things that benefit from constantly varied, functional movements performed at a high intensity.

Does that mean you shouldn’t use heart rate at all? No. It is a bit like weighing yourself on the scale. It is a piece of information but it isn’t all the info you need.

You can measure oxygen consumption (if you’ve ever heard of VO2 max, that’s what this is) but to do that requires a fairly elaborate setup. It would be very hard to do this while lifting weights, doing pull-ups, jumping rope, or performing heavy sandbag carries. In fact, oxygen consumption only works for measuring intensity of aerobic exercise (aka “cardio”) while you’re actually doing it. You can figure out how much oxygen you were forced to consume to recover from exercise after the fact in something called Excess Post-exercise Oxygen Consumption, or EPOC. Which I wrote about here. But that requires an even more elaborate setup that we won’t get into.

You can use fuel consumption as a measure based on what percentage of the fuel you are burning is carbs vs fats. The higher the percentage of fuel being used is carbs, the higher the intensity. The higher the percentage of fuel being used is fats, the lower the intensity. But measuring this is obviously very difficult and most of the time must be estimated. The estimate is based on… you guessed it… heart rate!

High intensity is a pillar of CrossFit because it is where the real results are at. I tell this to every person who I take through foundations. The only secret is that you have to keep showing up and you have to try hard. If you do that, you’ll become the fittest version of yourself. To measure health, Glassman uses a spectrum (pictured below). One end of the spectrum is Fit, on the other end is Sick, and in the middle is Well. The measures that are used to move you up and down that spectrum are all just that, things that can be measured. Blood Pressure, Body Fat %, Bone Density, Muscle Mass, Triglycerides, HDL/LDL, etc. Simply put, functional movements are awesome and varying those movements is very important, but their effect is minimal without intensity. We don’t want to just be Well. Well is just not Sick. We want to be Fit. Intensity will get you Fit.


Image result for crossfit sickness wellness fitness continuum

author: Jacob Watts


Leave a reply