bluebear, you may be right, with limited extension being ok, but i would only stabilise in neutral. from my experience anyway, extensions may help if it is hydrated disc, but then you need force to 'reduce' any disc bulge, ie mckenzies. otherwise all you are doing is gradually improving an extension dysfunction. also with spondy extension tends to make it worse, regardless of any osteophyte or other degeneration, which there is likely to be anyway, as it exagerates the slip, further closing the foramen and irritating the nerve. there are other causes of pain with prolonged sitting than a disc, postural overload, muscular-ligamanetous tension etc which would be better suited to advice to avoid prolonged sitting rather than to do extensions. my opinion anyway and difficult without patient to assess and try out on