In lumbar stenosis, the spinal nerve roots in the lower back are compressed, or choked, and this can produce symptoms of sciatica -- tingling, weakness or numbness that radiates from the low back and into the buttocks and legs - especially with activity.
In rare cases, lumbar stenosis can go no further than to produce severe persistent disabling pain and even weakness in the legs. Most cases of stenosis in the lumbar spine, however, have pain that radiates into the leg(s) with walking, and that pain will be relieved with sitting. This is called claudication, which can also be caused by circulatory problems to the legs.
Source : spin-health.com