It comes up all the time to the unfamiliar: “CrossFit is just HIIT, right?” Before I give you my take, let’s take a look at High-Intensity Interval Training, or HIIT.
What Is HIIT?
HIIT is a great way to burn a lot of fat, sculpt muscle, and build athletic efficacy in a short amount of time. Now the public is finding out that HIIT works! Fitness fads, such as the “Insanity” and “P90X” DVDs build upon this method, as well as the actors who starred in the movie “300,” who had to transform their bodies into Spartans in a short span of time. Along with the rapid evolution in social communication, it didn’t take long for the public to figure out the secrets of the professionals.
So, it “burns a lot of fat, sculpts muscles, builds athletic efficacy…” Sounds a lot like the benefits of CrossFit; therefore many people assume that CrossFit and HIIT must be the same thing. But let me explain why that is only a partially-correct answer.
“The Fran Example”
Fran is a set-structure of 21-15-9 thrusters followed by pull-ups for time. Most CrossFitters achieve this by breaking them up; one example is to do 3 sets of 7 reps for the 21, 3 sets of 5 reps for the 15, and 3 sets of 3 reps for the 9. It’s intense, it’s broken up into sets and reps with little rest and it’s done rapidly; so yes, that’s an interval workout.
But consider this: for a competitive CrossFitter, is Fran an “interval exercise?” Some of the elite have sub 2-minute Fran times, and they don’t break that up at all; it’s a continuous motion from 21 thrusters and pulls ups all the way down to the last 9. So Fran is only a “HIIT exercise” if you scale it down to one.
What I’m trying to say is, HIIT is not inclusive enough to be considered the exact same as CrossFit. You can do “Fight Gone Bad” — one of the more a more classic benchmark workouts — every single day, but is that “CrossFit”? Where’s the constant-variance? Where’s the broad modal and time domains? Where’s the unknown and unknowable?