The spine has a natural curvature that is principally controlled by the muscles running alongside and in-between each vertebra.
This natural curvature can be disturbed by disease processes such as tuberculosis, ankylosing spondylitis and osteoporosis, but most usually is affected by bad posture.
Little or no training is given in the West to good posture, whereas the Eastern philosophies, either through the martial arts or simply by a differing view of etiquette, encourage us at a younger age to keep the back erect. Hard mattresses have been replaced by soft ones and only in the last decade or so has the concept of an orthopaedic mattress been recognized in helping bad backs. Poor spinal curvature and lack of good muscular support is the cause of most backaches, whether initiated by trauma or not.
This is a forward curvature of the lumbar spine. This increase in the concave natural bend is usually created by carrying excess weight in the abdomen in association with poor abdominal musculature.