What people refer to as ‘bad posture’ often is known in the movement profession as Kyphosis, or a Kyphotic thoracic spine. This basically is in reference to an apparent forward ‘lean’ in the mid-back giving the appearance of slouching. Often you will see exercises to address this by merely addressing the apparent ‘forward lean’ with some sort of back bending, or using a roll to extend the mid-back over, etc.
When considering motion segments we must consider how the bones move on one another and also how the joints behave while the bones are moving on one another. In the middle to upper thoracic spine the bones move on one another predominately side to side and with rotation. The joints, on the other hand, glide ‘up and forward, down and backward’.
To address/restore the apparent forward bend, moving the bones of the thoracic spine in rotation and side-to-side will be in agreement with how the bones are predominately made to move. Interestingly enough, deep spinal postural muscles that act as ‘bowstrings’ to pull the body in an erect position act individually with rotation and side-to-side movements.
So when thinking of addressing posture, consider the 3 planes and combinations in which we move. Forward/backward, Side-to-side, and rotation.
And we’re not even touching on the nervous system…