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That belly is heavy and you just want to put your feet up.
But how you spend your days shapes your body. And the shape of your body (how the muscles and bones are all aligned), shapes your birth.
What happens when you sit a lot
What I'm going to describe happens to all of your muscles everywhere all the time. But I'm going to focus just on one muscle and one activity and what that does. The muscle I want to focus on is the psoas and the activity is sitting.
Your psoas runs from the transverse processes of your lumbar spine, travels through your pelvis then attaches onto the lesser trochanter on your upper inner thigh.
The psoas is a hip flexor. That means that when we sit, the muscle is in a shortened position and when we stand, it is in a lengthened position.
If we sit for an extended period of time, our body is smart, and it’s not going to waste all the extra muscle length that’s normally available when you’re standing. It's gonna say “oh, we don't need all of that extra length, so I'm gonna put my energy somewhere else and we're just going to conform this muscle to the length that it's always being used in.”
Now the problem comes when we go to stand up and we don't have that give of the muscle anymore. We stand up and because the hip is “stuck” in flexion, we can’t get fully upright. Then to compensate, we lift the ribs and shoulders back leaving the pelvis is what’s called an anterior pelvic tilt.
Why it happens
When you're pregnant, you get tired. You spent more time than usual sitting. I remember it well!
If you have a desk job, if you're driving, if you're commuting a lot, and you're not walking to counterbalance and get the psoas to stretch back out again, you can end up creating a compensation pattern of the short hip flexors in the front, and underactive glutes and hamstrings in the back. This leads to that anterior pelvic tilt - that tip forward.
It's such a typical pregnancy posture. The weight of the growing baby naturally pulls your center of mass forward and if we aren’t aware of this, the anterior pelvic tilt makes an appearance.
This tilt can cause low back pain or a variety of other pregnancy aches and pains.
But even if you are feeling good, there’s of course a birth reason why we’d want to avoid that posture as well.
How it effects birth
When you’re in an anterior tilt, gravity can’t help baby drop down and engage into the pelvis because they aren’t lined up.
If we bring the pelvis back to neutral, or better yet, practice a good posterior tilt, baby can engage into the pelvis. Then once baby is engaged in that pelvis, they can work their way down and then we can do other positions to help baby exit.
So while you might not necessarily have low back pain in pregnancy, common as it is, there are still biomechanical reasons why we would want to bring the pelvis back into neutral to help with baby's positioning, and baby's ability to navigate the pelvis during labor and delivery.
I have a class HERE that will help undo all of that sitting. The class focuses on the psoas, both stretching it and then also strengthening it so it can have that full, supple range of motion.
If you feel like you are starting to get a little bit of that anterior tilt or you're starting to experience some low back pain, or you realize that you are sitting more than you wished you were, click HERE and get that free 25-minute workout.
As always, I’m happy to answer any and all questions!