A few years ago, the Swiss ball migrated from the gym to the office en masse. Swarms of desk jockeys rolled them into their cubicles, convinced that sitting for eight straight hours on a rubber ball counted as "exercise" and provided them with a subtle abdominal workout that sitting for eight straight hours in a chair did not.
Here, no less a man than Dwight Schrute explains the ball-chair's many benefits:
Unfortunately, Dwight and every other ball-chair sitter (including one mental_floss staff member who shall remain nameless) were making themselves look silly for nothing. Sure, the hype is all positive and the anecdotes of friends of friends make sitting on a ball seem great, but the data tell a very different story.
In 2008, researchers from the University of Waterloo had folks sit on both an exercise ball and an office chair for 1 hour each while performing various routine computer-based office tasks. Spinal posture and the activation of eight different muscles were recorded, measured and analyzed. While sitting on the ball, the the subjects' showed increased activation of one muscle group and decreased pelvic tilt (too much of which can be a postural problem) versus sitting on the chair, but also complained of increased discomfort. The researchers concluded that the small changes in biological responses were not significant and didn't outweigh the perceived discomfort enough to make prolonged sitting use advantageous.
A 2006 study by a different group of researchers from the same university was even more damning. That group had volunteers sit for 30 minutes each on an exercise ball and a wooden stool. Spinal posture and position, activation of 14 different muscles, and the pressure distribution over the volunteers' butts were all looked at. They found no difference in muscle activation between the ball and the stool, and concluded the ball had no effect on the volunteers' "muscle activation, spine posture, spine loads or overall spine stability." Like the the other study, their volunteers complained of lower back discomfort after sitting on the ball. The researchers suggested this was because the ball creates more butt-to-seat contact area, resulting in uncomfortable soft tissue compression.
So the fitness orb isn't the miracle workout Dwight claimed it to be, but there is a silver lining. If you've already got lower back problems, bouncing away at your desk might ease your pain. In 2007, two chiropractors from British Columbia (what is it with these Canadians and the Swiss Ball?) published some case studies from their practice, explaining that, for a few of their patients, short lengths of time on a ball reduced the recurrence and severity of back pain. (An important lesson gleaned from this paper is that the patients who saw a benefit didn't spend all day on the ball. They only sat while they were comfortable, whether that was for 2 minutes, 20 minutes, or several hours of their workday.)