OK, so here’s me and what might be your initial assessment of my posture? Upright back, hips open fairly well, collar bones wide?
Looking a little more closely however, we might see that sitting directly on the floor as I am, my pelvis has rolled backwards in a posterior pelvic tilt, dragging the sacrum with it and drawing the lumbar spine out of its natural lordosis and into flexion. In my efforts to counter this I am over-extending at the thoracic spine so that the lower ribs have lifted and the neck posture is thrown out of alignment too; there is over-exertion of many muscle groups – most obviously perhaps the ones on the front of my neck which are standing out with effort.
Let’s consider too the effect on the breath. The movement of the diaphragm is restricted reducing the breath into the belly, the overly-extended thoracic spine is reducing the available expansion of the chest, and the tight anterior neck muscles are hampering free movement across the upper chest.
Hmmm… All in all not good at all for any length of time – get off my butt and onto the Buttafly then!