An exercise ball, also known as a stability ball, is traditionally used in exercise routines as means to improve balance, allow exercisers to do exercises they would not otherwise be able to do (i.e. using the ball against a wall to squat) and expand range of motion (i.e. crunches).
Use of exercise balls has moved out of the gym and into the office, where increasing numbers of people use them in place of chairs.
The idea of sitting on the ball versus a traditional chair is that this change can increase core strength, since the abdominal muscles must be constantly engaged to avoid falling off. Improving core strength means improving posture, balance, and stability. Proponents also cite increased calorie burn as a benefit of maintaining your balance throughout the day.
Opponents of using exercise balls to sit on at work argue that what is desirable in a chair is not the same as what is desirable in a piece of exercise equipment. A chair, they say, should take pressure off of the low back and provide support for the arms, which can alleviate discomfort and lessen fatigue. The constant muscle activation required when sitting on a ball for prolonged periods can increase fatigue and make back pain worse.
I found a number of studies examining the benefits and drawbacks of sitting on an exercise ball at work. With a few exceptions, the research overwhelmingly shows that a chair is a better option than a ball, at least when you’re at work.
A 2006 paper published in Human Factors examined differences between sitting on a stability ball and in an office chair in terms of trunk muscle activation and lumbar spine posture.1 The authors found that, though there was a small increase in the activation of certain trunk muscles, sitting on a ball resulted in significant discomfort. So, their recommendation is to avoid using a ball for this purpose.
Another study looked at similar variables and found an increase in “spinal shrinkage” in people who sit on an exercise ball,2 which certainly doesn’t sound desirable.
Yet another research paper concluded that “prolonged sitting on a dynamic, unstable seat surface does not significantly affect the magnitudes of muscle activation, spine posture, spine loads or overall spine stability.” The authors also found higher levels of discomfort in the stability ball users, which may be a result of soft tissue compression against the ball.3
I found 1 paper that supports the use of stability balls for decreasing pain. In a case report published in the Journal of the Canadian Chiropractic Association, 2 low back pain sufferers reported improvement in symptoms after changing from a chair to a ball.4
Sitting on a ball versus a chair may increase passive caloric expenditure. A study from SUNY Buffalo showed a 4.1 calorie per hour increase in energy expenditure from sitting on a ball versus a chair.5 This translates to an extra 32 calories over an 8-hour work day.
In short, yes. Chances are you will experience more low back and neck discomfort without any benefit to your posture or core muscle strength. If you like the idea of the extra calorie burn, you can get the same effect from walking 1/3 of a mile at lunch or during a break. Getting up from your chair a few times per day, stretching and walking around the office will also do more to improve your posture and reduce pain than sitting on a ball.
The idea of improving your health while doing something you have to be doing anyway is attractive. However, this is not a good means to do it. If you want to improve your health, eating healthfully, being active, stretching, and engaging in an effective exercise program are much better ideas than swapping out your chair for an exercise ball. Save the exercise ball for crunches and wall squats.