Loss of Lumbar Curvature (or Lordosis) (picture): The curve in the lower back (Lumbar) is meant to decrease the weight felt by the spine and muscles by gaining mechanical advantage with a curve. For example, structures with curvatures or arches tend to be stronger. Ancient Roman structures that are still standing mostly have arches (a good example is Pont du Gard - Picture). If someone has a loss of this arch or straightening of the lumbar lordosis then they feel a heavier load because of the loss of advantage. The heavier load leads to speeding up the degenerative processes of the joints. Additionally, when there is a heavier load then the muscles have to activate to a larger degree to hold the weight. Eventually, the muscles will spasm and give out. This leads to low back pain. Often people put their hands behind their backs to alleviate the pain. The symptoms of this condition are relatively easy to treat but it will continuously return unless the underlying biomechanical issue is treated.