Exercise balls are becoming an increasingly popular alternative to traditional office chairs, as desk workers seek out ways to counteract the effects of sitting for 8 hours a day. Using an oversize inflatable ball as a desk chair may certainly add some novelty to the workplace, but does sitting on the ball provide any actual benefit in terms of posture, back pain, or overall fitness?
I get asked frequently whether or not using an exercise ball as a chair is a good idea, and unfortunately there is no clear, straightforward answer. I can understand how in theory the ball may provide some benefit, and plenty of anecdotal support exists for the superiority of the the exercise ball over the typical office chair. Research into the matter, however, has yielded some conflicting results.
According to a 2008 study, performing clerical work sitting on an exercise ball burns about 4 calories more an hour than performing similar work sitting on a traditional chair. This would amount to about 30 extra calories a day burned by using the ball as a chair, a small but potentially meaningful amount for someone looking to increase their daily calorie expenditure. Bouncing or performing other activity while on the ball, though not accounted for in the study, could potentially add to the calories burned. Also not determined by this study was if the increase energy expended was due to the novelty of sitting on the ball, which could mean the calorie count could return to baseline after a period of adaptation.
Better For Your Back?
Back pain is one of the most common causes of work-related disability in the United States, costing nearly $50 billion annually. The strain placed on the spine from prolonged sitting is suspected as a major contributor to back injury. Conventional wisdom has been that “correct posture” entails sitting up straight with the knees and hips both bent at 90 degree angles. Several studies have demonstrated that the sitting position that places the least amount of stress on the back is in a chair reclined between 110 and 135 degrees. It can be argued that sitting on a stability ball encourages the user to sit straight, but if a reclined position more akin to lying down places less stress on the spine then the ball is at a disadvantage due to the lack of a back rest. A 2009 British study found that 30 minutes of sitting led to slouching regardless of whether subjects were using a stability ball or a desk chair with the back rest removed. This study also did not look at the long term effects of using the ball on posture, but the findings suggest that individuals will assume bad sitting posture no matter what they’re resting on.
A 2009 study by a group of Dutch researchers compared female subjects performing a typing task for one hour while sitting on an office chair with arm rests and sitting on an exercise ball. Sitting on the ball produced more trunk motion and more muscle activity than chair sitting. These finding would seem to be an advantage to use the ball, but the study also found increased spinal shrinkage, and indication on compression forces on the spine, when subjects sat on the ball. This authors of the study concluded “that the advantages with respect to physical loading of sitting on an exercise ball may not outweigh the disadvantages”.
A 2006 from the University of Waterloo compared muscle activity and spine position in a small group of male subjects sitting on an exercise ball and sitting on a stool for 30 minutes. The researchers found no significant difference between the two groups for activity in 14 muscle groups and spine position. They also calculated that there was no difference in spine loads and overall stability.
Another study from a different group of researchers from the same university also examined the effect sitting on an exercise ball has on muscle activity and spine position. Participants for the study were a group of 14 men and women who performed various tasks for a total time of 1 hour while sitting on a standard office chair and an exercise ball. The study found no difference in muscle activity except for an increase in one of eight muscle groups being measured in subjects sitting on the ball. The only difference in spine position measured was an increase in posterior pelvic tilt in subjects using the chair. Posterior tilting is typically associated with increased lumbar flexion, or rounding of the back in sitting, but the researchers reported no difference in flexion of the low back between the two groups. The study noted increased reports of discomfort from the the participants when sitting on the exercise ball.
While these studies suggest there is no advantage to using an exercise ball in place of a chair, and the potential for decreased comfort, there are several major limitations in the cited studies that make drawing conclusions from them difficult. The studies were all small in size, and all included subjects participating in a novel activity. Would muscle activity, posture, or comfort levels be different if the subjects were tested again after several months of using the exercise ball? I can understand how making the switch might be uncomfortable initially for anyone not accustomed to using an exercise ball. One of the studies required the subjects to sit on the ball with their feet flat on the floor at all times for an hour, which probably doesn’t replicate the way a person would typically sit on the ball. Additionally, muscle activity was recording using surface EMG which would not be able to detect activity in muscles closer to the spine that may play a role in stabilizing the back.
An issue that has yet to be addressed by researchers, but has been acknowledged by some companies and regulatory agencies is the safety factor of using as unstable air-filled device as part of a workstation. A worker could lose their balance and fall off the ball or the ball itself can roll off and become a tripping hazard. There are stands available that hold the ball stable but this seems to defeat the purpose of using the ball instead of a chair.
There is some evidence that substituting an exercise ball in place of an office chair will burn more calories and increase muscle activity, but sitting on the ball may not necessarily result in improved posture or decreased pain. Frequently changing position is one of the easiest ways to avoid the dangers of sitting and having the ball for a chair may encourage the user to move more than they would if they were sitting on comfortable, cushioned chair. On the flip side, for someone who has no choice but to sit in the same position for extended periods, it seems that having a chair with a reclining back and arm rests may help decrease pressure on the lower back. It’s a difficult call, but given the research so far I don’t think there is enough evidence to recommend trading in the chair for a ball full time. Provided there is enough space, a better option would be splitting up the workday between perching atop the ball and sitting in a chair, but most importantly, reminding yourself to get up and move around at least once every hour.