While I do have a physioball that I used as my office chair at West Point and I don't have any problem with them being a PART of a balanced core training routine, this video pretty much sums up my feelings on unstable surface training and the way it's been pushed as the or athletic development. By the way, what is "Core Stability"? Has anyone seen a reasonable definition that holds up against scientific scrutiny? Luckily, I think we're beyond the crest of this fad.