[Editor’s note: This is a guest post by Nadine Fawell who blogs at Yoga with Nadine. Check it out!]
Well, I think it is anyway. There are many, many reasons I think this: I could practically write a BOOK about the psoas.
But here’s something to think about.
When we went from walking on four legs to walking on two, we had to find a way to hold our upper bodies, well, up.
In four-legged creatures, the spine is happily suspended between front and back ends. In our case, it pokes up into the air. Our back muscles and belly muscles, and most especially our buttocks muscles had to get a whole lot stronger to hold us up that way.
We developed a gluteus maximus on each side of our butt (that muscle is just called gluteus superficialis in four legged animals). Its main job?
To hold us upright by bringing our hips into extension (backbending). That’s why it’s so big. It has to be, to defy gravity.
See, in this picture:
I am bending backwards and you can see my, erm, gluteus maximus, is working, yes?
I only look so happy, though, because I know I can contract my psoas muscles in the front of my hips to oppose the action of my butt and return me to an upright position.
The psoas is a deep muscle in the front of our hips, which hooks our spines to our thighbones.
Without the psoas, whose main job is to bring the hip into flexion (i.e., thigh closer to belly), those big-ass butt muscles would make it impossible for us to use our arms the way we do now.
Imagine doing a backbend like I am in the photo, and trying to read this post. Or do anything at your computer.
That’s right, if you didn’t have a psoas (also known as a hip flexor) on each side, you wouldn’t be able to bend your leg up against gravity, and the action of your glutes, and take a step.
This shows up in yoga postures too, of course – a tight psoas would make bending backwards like I am doing in the photo really difficult.
Plus, if you couldn’t contract your psoas to lift your leg against gravity, how else would you do Utthita Hasta Padangustasana (aka Extended Hand to Big-Toe Pose)?
That, ladies and gentlemen, is the first reason I think the psoas is the most important postural muscle. There are others, involving magic links and its action on the spine. But opposing our glutes and keeping us upright? Pretty important.