Kettleballs
Can Kettleballs help back pain?
I've never tried kettleballs, but this article from the NY Times caught my eye. It showed that done correctly execising with kettleballs can be very beneficial for back pain. Kettleball exercises include swinging which recruits core muscles if done correctly. I think these should be sold with a warning to not try this at home. If you're interested in learning to use kettleballs please get expert instruction.