The SI Joint and Shock Absorption


Hi everyone!  Here’s a new concept I haven’t written about as much yet.  I find it really interesting, and I hope you will too!

What I wanted to talk to you about is the SI joint’s role in shock absorption.

The SI joint is different from a lot of other joints in the body, in both its form and function.  (These are the official terms you’d learn in an anatomy class!)

What this means is that the SI joint has a pretty unique shape, compared to other joints in the body, and also that it has a unique job to do.

One of the SI joint’s main roles is shock absorption.  This is sort of similar to what people mean when they talk about shock absorbers in a car.

In a car, as in people, a certain amount of force is going to travel up the tires (or legs) as we move over the ground.  There will be more force if we’re moving quickly, and particularly if we hit bumps– or land harder on our feet, as in the case of running.

So one role of the SI joint is to receive some of this force that comes up the leg when we walk, run, or jump, and direct it in controlled way as it continues up the rest of our body.

We don’t want a ton of force to hit any one part of our body in one targeted spot.  For example, we don’t want all of the force of our foot hitting the ground to be directed to a one-inch spot on one of our lumbar discs.

Much better, instead, to have some “give” at the SI joints, which can spread that force out over a much larger area throughout our pelvis and trunk, so that the amount of force that hits any one small area is greatly reduced.

Now, once in a while, I read an article by some skeptic in the world of PT or a related field, who claims the SI joint doesn’t move at all, or serve a function.

Of course, this drives me completely insane.  First, I’m going to share some articles where some actual MD’s back me up on this (check out the links at the end of the post).

However, I can also tell you that I’ve personally experienced the role of SI joint as shock absorber in my own life, and it’s 100% real.

How do I know?

Pay attention to how your SI joints feel when you’re riding in a car.

When my SI joints are in place, I can go over a bump and feel almost no pain.

However, during my five-year saga, when my joints were really out of place, I would feel every little bump and dip in the road.   I’m talking everything.

If no one was behind me, I’d go about 10 miles under the speed limit, taking care to purposely avoid roads where the pavement was really torn up.

When I started to get better, I started to notice I was driving a lot faster.  Not that I advocate speeding– I’m simply saying that the pain that had served as a reminder for me to slow down was gone.


It’s because, with my SI joints in alignment, my body was finally able to distribute forces efficiently again.

When one of my SI joints were locked up, the force of going over a bump wouldn’t get dispersed properly.  The joint needs to be in place to do its job– otherwise, that force didn’t get directed the way it was supposed to, and I’d feel it in the joint.

But with the joint in alignment, I stopped really noticing the bumps in the road.  I didn’t even notice the change consciously at first– it’s just that all of a sudden I found I was able to start going the speed limit again, and 40 mph no longer seemed impossibly high.

This is something you might be able to notice in yourself.

I know that some of you aren’t really able to tell when your SI joints are in alignment or not.  I think that, in part, this is because some people have symptoms that are due more to inflammation in the joint, rather than the joint being out of place itself.

But for those of you whose symptoms do involve the joint moving out of place, you may find this is something to pay attention to.  Are there days when you find riding in the car to be much more painful than others?  This could be a sign that your joints are out of alignment.

To learn more:

Here’s an awesome TIME magazine article, How Your Butt Can Hurt Your Back. The author speaks with Dr. Alice Chen, a physiatrist at the Hospital for Special Surgery in New York City, on the role of SI joint as shock absorber.

Okay… that’s all for now! 

Hope this was helpful!

Published by Christy Collins

Hi, I'm Christy! I'm a health coach who helps people overcome SI joint dysfunction and chronic pain.

2 thoughts on “The SI Joint and Shock Absorption

  1. Hi Christy, My name is Katrina. I’ve been reading all your posts. Thank you thank you. I won’t go into my whole story at the moment; it’s too long. And I may actually want to set up a call with you. However, I am so curious – How did you get a clear diagnosis for your SI joint problems? I have had one neurosurgeon say (from testing and MRI) that my leg pain is absolutely SI, and I have others say it’s not and it’s more the mild stenosis in my spine (I’m 68 and have been riding horses avidly all my life). Also did you work remotely with your PT in RI? Or do you live out there? I’m in Colorado. Thanks so much.


    1. Hi Katrina, glad my site has been helpful! There are a few potential ways that people are able to get a diagnosis of SI joint dysfunction.

      For me personally, I arrived at this diagnosis after first a chiropractor, and later a skilled physical therapist, were able to assess my alignment and restore my mobility to move normally by correcting my SI joint alignment. However, this isn’t necessarily the only way to go about it– when there’s a question of whether your pain may also be coming from the spine itself, there are additional things you can do, and tests you can ask for.

      One of the big things I do in my coaching program is help clients find their way through the medical system and get clarity on their diagnosis– I’d be happy to speak with you, too!


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