Why SI belts help some people, and not others.

Hey everyone!

I know many of you are curious to learn about SI belts. They can be a powerful tool in recovery, and are really helpful for a lot of people.

In this study, researchers used a detailed computer model, using all that’s currently known about the sacroiliac joint’s movement, to examine the effects of compression with an SI belt.

They identified two main reasons why people may find the SI belts helpful:

Altering Joint Movement:

First, the study authors found that when the belt was applied, it changed the way the SI joint was able to move. The belt increased motion in the sagittal plane– in other words, the joint was able to move more in a “front-to-back” direction.

However, the belt actually lessened the joint’s ability to move in the transverse plane– in other words, it wasn’t able to move as much in a side-to-side direction.

This makes sense, of course, when you think about how the joint compresses the joint inwards towards the body, in a side to side direction. It literally squeezes the joints in from the side:

donjoy SI belt

  • sacrospinous
  • sacrotuberous
  • and interosseous ligaments
SI joint ligaments
ligaments of the SI joint

Neuromuscular component

The study authors also conclude that the SI belts might also be helping in a second way, which is by improving the neurological feedback mechanisms that help to support the joint.

What does this mean?

Ligaments don’t only support the joint in a passive way. They aren’t simply these “cables” that connect one bone to the next.

Instead, they contain special receptors that help tell your nervous system where your body is in space, and what’s going on with the joint.

These receptors can tell your nervous system to contract the muscles around the joint, if they sense it’s unstable or that something may be wrong. Under normal circumstances, we don’t perceive our muscles and nervous system working this way– it’s happening underneath our conscious awareness.

However, when your ligaments have been injured, the communication between the rest of the nervous system and receptors can also become disrupted.

That means our nervous system is no longer receiving these feedback messages, and our muscles are not activating to stabilize the joint in the same way. This is part of why low back pain in general can become chronic, even after our initial injury should have “healed”– it’s because that neurological feedback that’s supposed to help us has been disrupted.

The study authors conclude that wearing the belt can actually help to turn these neurological mechanisms back on– a process that I think is pretty cool!

This study outlines both of the main reasons why an SI belt can help some people– and not others.

As you guys know from my last post, some people love the SI belt, while others don’t seem to get any relief from it at all (for example, I hated it!).

This study provided a really good explanation for the different responses people get:

  • The belt also altered muscular activity, changing the patterns of which muscles may be active, and which may be underactive. For some people this may be a beneficial change, depending on whats going on. However, for me, I strongly believe this is exactly the feeling I hated!
  • The belt increased activity of the stabilizing neuroreceptors, which can help turn those automatic stabilizing mechanisms back on.

So… I just thought this was cool!

This was definitely one of my longer posts… it’s been a while since my last science class, so my brain really wanted to delve into this today. 🙂


And of course, if you want to check out the full study, you can find it here:

Happy researching!




SI belt photo: DonJoy

Published by Christy Collins

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

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