The daily habits of posture and use, at work and leisure, are frequently the unobtrusive, non-violent, yet persistent factors which mitigate towards somatic dysfunction and the consequences of general ill-health. Posture represents the sum of the mechanical efficiency of the body. It may be read as a book, to assess the integrity, potential, and to some extent, the history of the individual.

The ideal posture is one in which the different segments of the body, the head, neck chest and abdomen are balanced vertically one upon the other so that the weight is borne mainly by the bony framework with a minimum of effort and strain on muscles and ligaments. For such posture to be maintained, special postural muscles must be in a state of constant activity. These have a special physiological property called 'postural activity'. Correct posture is one in which the head is centered over the pelvis the face directed forwards, and the shoulder girdle approximately on the same plane as the pelvis.

The position of the bony framework is determined by the soft tissues which invest, support, bind and move it. Faulty tensions in these soft tissues will lead to abnormalities in the skeletal structures, and therefore to function itself. This may also result in changes in the organs and functions (circulation) which are supported by soft tissues. Not only are the soft tissues subject to gravitational stress, but also to a battery of postural and occupational stresses overlaid with the normal contraction that come with age. Goldthwait [1] points to the importance of posture in the maintenance of health:

It has been shown that the main factors which determine the maintenance of the abdominal viscera in position are the diaphragm and abdominal muscles, both of which are relaxed and cease to support in faulty posture. The disturbances in circulation from a low diaphragm and ptosis (sagging organs) may give rise to chronic passive congestion on one or all of the organs of the abdomen and pelvis, since the local as well as general venous drainage may be impeded by the failure of the diaphragmatic pump to do its full work in the drooped body. Furthermore, the drag of these congested organs on their nerve supply, as well as the pressure on the sympathetic ganglia and plexuses (nerve centres), probably causes many irregularities in their function, varying from partial paralysis to overstimulation. Faulty body mechanics in early life, then, become a vital factor in the production of the vicious cycle of chronic diseases and present the chief point of attack in its prevention .... In this upright position, as one becomes older, the tendency is for the abdomen to relax and sag more and more allowing a ptosic condition of the abdominal and pelvic organs unless the supporting lower abdominal muscles are taught to contract properly. As the abdomen relaxes, there is a great tendency to a drooped chest, with a narrowed rib angle, forward shoulders, prominent shoulder blades, a forward position of the head, and probably prorated feet. When the human machine is out of balance physiological function cannot be perfect; muscles and ligaments are in an abnormal state of tension and strain. A well poised body means a machine working perfectly, with the least amount of muscular effort, and therefore better health and strength in daily life.