My walking program is based on the idea that most people are leaning backwards and compressing their spines with the way they walk and stand. They do this in large part due to muscle imbalances between the front and back of the body, but the main reason that everyone leans backwards is because they can.
We are the first beings to have a curve in the lower spine. If you look at the spine of the dog in the picture above below it is flat and sits horizontally with its weight distributed over the front and back legs. Our vertical spine could not be flat—and vertical. The curves of the lumbar and cervical spine support the transfer of weight from the head down to the feet.
In the same vein the psoas major, my favorite muscle, had little to do in a four-legged animal. When we came up to stand it was the awakening and engagement of the psoas that created the lumbar curve as it was pulled tight across the rim of the pelvis.
When we stand upright the responsibility for maintaining the balance of the upright spine falls to us but we pay it no mind. Almost everyone I ask thinks they are standing up straight. Almost nobody is. People are leaning backwards slightly because over the long-term of doing so their lower back muscles have habituated to this kind of posture.
The only way to change this is to become aware that you are doing it. If someone thinks that leaning slightly backwards is standing up straight then it becomes a brain and perception issue. Self-awareness isn’t easy but you need at least a modicum of it if you want to change.
Take a look in the mirror and check it out. Or take a picture of yourself standing and I’ll let you know what I think.