For about two years I used an exercise ball (just the ball) as my main office chair. I eventually gave it up after discovering a couple of things:
1. I have a tendency to defeat any ergonomic device over time. While I'd start my work sessions vigilantly paying attention to posture, as I became more engrossed in the task at hand, my body would subconsciously find a way to stay balanced on the chair while increasing the amount of slouch.
2. An exercise ball on the floor quickly gets filthy. And as the ball rotates around, eventually you wind up sitting on a dirty spot.
Ball chairs like the one seen in the photo above take care of problem #2, but how are they at problem #1? I always assumed it was a matter of personal proclivities, that the alert user would find the ball worked well for them, while the slovenly like me would fail to reap any ergonomic benefits over time.
In Ergonomics Today, chiropractor Ian Chong attempts to get to the bottom of the matter with his "What's the Hubbub About Ball Chairs? Are They Really Ergonomic?" article. "We put together a small informal task force made up of some users, Certified and Associate Ergonomists, physical therapists, engineers, occupational therapists, and exercise physiologists—all professionals and all, not surprisingly, with opinions," writes Chong.
Users were quizzed on the ball chair across six categories, with the results posted here and some further analysis and conclusions drawn here. (Those links are to Parts Two and Three of the article, the relevant parts, as Part One is all filler and set-up.)