Suggest using an exercise ball as a desk chair, and you may be met with anything from enthusiasm to bafflement or wild derision. Despite anecdotes from adults pleased to have made the switch from desk chair to exercise ball, sitting on a ball all day is still seen as outside the norm. And although there is some evidence about the positive effects of sitting on an exercise ball for an extended period of time, there are some downsides too.
Seat of Discomfort
In a pair of small studies about exercise-ball seating conducted at the University of Waterloo, some subjects reported discomfort when sitting on an exercise ball for an extended period of time. Researchers speculated that this might be due to increased soft tissue compression, resulting from the larger contact area while sitting on a ball as compared to an office chair.
Risk of Falling
One of the big draws for sitting an exercise ball instead of an office chair is the idea of getting an ab workout without any extra effort. It's true that for the very deconditioned, just the act of maintaining your balance while seated on an exercise ball can present a challenge; but this also introduces a potential risk. You could be hurt if you fall off the ball in a moment of distraction or inattention to balance.
Lack of Support
The Waterloo studies showed only very minor changes in muscular activation when sitting on an exercise ball as compared to sitting in an office chair. But some still view the exercise ball's lack of back support as a definite contrary aspect. Using the ball is no guarantee that you'll develop great posture; you can still slouch if you so choose.
Potential for Bursting
Although exercise balls are made of very tough plastic, they're still essentially giant balloons. Accidentally roll your ball over a dropped thumbtack and it will burst, landing you suddenly on the floor. Even burst-proof exercise balls will deflate when punctured, although they usually do it slowly enough that you have a chance to get off, instead of being unceremoniously dumped.
Exercise balls don't require much maintenance. But if you notice that the ball compresses more than six inches when you sit on it, it has lost some air and needs to be reinflated.
Although some studies have shown that exercise balls help increase engagement in focus groups, they may present a distraction to some. If you find the constant movement of the ball beneath you or the temptation to bounce on it distracting, you might be better off in a conventional chair.