Crunches R bad, mmmkay?

This is prompted by a discussion I had with another coach out at the Kore Cross workout in Redmond last night. The group warm up included a double set of crunches. Crunches? For Cyclists? Yikes…

Here’s where I’m coming from…

I spend the majority of the time that I’m not sleeping or working doing one of two things; riding a bicycle or rolling Brazillian Jiu Jitsu.

These are both highly spinal flexion intensive sports. This can be bad news.


OK. Lets start by establishing the terms under discussion.  A picture is worth a thousand words:


So, “Flexion” and “Extension.” Got it? OK…

Next –

Flexion is pretty bad.

Huh? Why?

Here’s what Flexion looks like when someone rips your spine out of your body:


So? Big deal!

It is a big deal.

If we really dramatically simplify things, we can visualize your spine as looking like a stack of Oreo cookies.



What happens to an Oreo if you squeeze one side of the cookie between your fingers?

The cream filling starts to squeeze out.

This is, essentially, what happens to the spine under flexion. Here’s another picture:


Notice the cream filling squeezing out of the spine in the Flexion picture? Yuck. Notice how it isn’t in the extension picture? Remember that…

OK. Scary stuff. Let’s take a step back…

The cream filling doesn’t immediately squeeze out the second you bend over and introduce Flexion. What does happen when you are in this position is that the pressure on the creamy filling increases. A lot.

Here’s some quantification of “a lot.”


Make sense?

OK. Over time, this increased pressure can cause lots of problems.

“Cyclist’s spend a lot of time bent over like that. They get used to it…”

The structures placed under these increased forces do not strengthen under increased stimulus, they get progressively weaker and more susceptible to damage. They do not heal from this damage. An adult human has no capillary blood flow to this area. There is no mechanism available to the body to heal damage to this area.

I repeat: Time + increased force = damage.  Look at that cookie picture again. Get one, and squeeze the edge of it. Watch how, the more you squeeze it, the easier it gets to do it. Do it long enough, and the cream squirts out.

This sucks.

When it’s your spine instead of a cookie, It hurts a lot. It  can be completely debilitating if the squirtation :o) is severe enough.

Why is this a concern for cyclists and Jiu-Jitsu players?




Make sense?

So, back to crunches.

Why are crunches so bad?

If you don’t do them with perfect form, they introduce significant Spinal Flexion. Very, very few people teach the appropriate flexion-free approach to this excercise (it certainly wasn’t done at the Marymoor workout.)

Frankly, cyclists and BJJ players get far more of this type of Flexion than is good for them to begin with. Just look at the pictures above.

If you are going to do crunches at all, you’re probably going to do lots of them, and this is just bad damn news. Take an inherently bad exercise and repeat literally hundreds of times? Yuck.


Scared off of crunches?


Wondering what you should do instead?

Here’s a good place to start:

Wondering why I asked you to note the difference between Flexion and Extension forces on the spine? More later…

Interested in more info and science on this topic? Here’s a place to start:

… and yeah; credit to the above link for several of the images used in the above post…


~ by crosssports on October 1, 2009.

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