The schemas are a set of 'types', each associated with a set of properties. The types are arranged in a hierarchy.he schemas are a set of 'types', each associated with a set of properties. The types are arranged in a hierarchy.
Inadequate stretching and warming up prior to exercise, or advancing your exercise program too quickly, or beginning a new exercise program, have all been known to cause symptoms. In some people, just vigorous walking or exercising on uneven ground is enough to exacerbate a flare-up of sciatica nerve pain.
Sciatica is caused by irritation of the sciatic nerve. A slipped disc is the most common cause of sciatica. Additional common causes of sciatica include: 1  Lumbar spinal stenosis (narrowing of the spinal canal in the lower back). 2  Degenerative disc disease (breakdown of discs, which act as cushions between the vertebrae). 3  Spondylolisthesis (a condition in which one vertebra slips forward over another one).