Many people have lower back pain because they lean backwards through life. They lean backwards through life because they can. Homo Sapien Sapien, our genus has a spine with four curves that are responsible for holding us upright. The great ape, our closest relative on the evolutionary ladder has a flat lower back—no curve in the lower spine.
There are a number of reasons that apes cannot walk upright for long periods of time. For one, they have weak pelvic muscles that force them to shift their entire body weight over each leg as they proceed forward. The second more important reason is the flat lower spine. They can walk a few feet upright but with nothing in the spine to support and transfer the weight of the upper body they soon fall forward onto all fours.
As we stood up the psoas muscle awakened to a new role that included the creation of the spine’s lumbar curve as the psoas crossed the rim of the pelvis creating tension that pulled the lower vertebrae forward. It is the small curve in the lower vertebrae that allows the rest of the spine, rib cage and head to remain upright due to its ability to transfer weight down into the pelvis and legs.
I think that a great deal of lower back pain and issues with the psoas arise simply from the fact that we lean backwards, both in standing and in walking. And again we do it simply because we can. The curve of the lower back requires a good deal of surrounding muscle tone in order to maintain balance in the front and the back of the body. If we don’t have enough tone in the front—and I don’t think many people have the balanced tone that I am referring to—it is likely that we will lean backwards and compress the lumbar vertebrae slightly. Over time this is what leads too much of the lower back pain that many people suffer from and I think it is most easily alleviated by changing one’s walking and standing patterns.