Function is the action of movement of every component of the structure in relation to each other. Efficient movement requires fluidity between the components and the knowledge of how to work within the force of gravity. Function is lost as the movement is restricted as it loses fluidity. After the structure is compromised, most bodies will shorten up the front of the spine over time: the shoulders and head get pulled forward and the back tends to start to curve over towards the front, causing the shoulders to stoop. This creates the need to re-balance the body so that the central axis is not compromised and the body can move.