Despite the popularity of swapping office chairs for stability balls, there’s no evidence it offers health or fitness benefits; and there’s some evidence for negative consequences.
Enthusiasts say ball-sitting activates core muscles, boosting core strength, endurance, and stability. But research evidence doesn’t support this claim. One study found no difference in activation of 14 different muscles between sitting on a ball vs. a wooden stool; spinal posture, loads and overall stability were also unaffected.
Another study found no significant differences in muscle activation or posture with ball sitting, but participants reported increased levels of discomfort compared to sitting in an office chair.
In addition, there are safety concerns regarding ball-sitting at work. Sitting for extended periods without back support can cause quite a bit of strain and discomfort; because balls are an unstable surface, users can fall off; stability balls have also been known to pop and deflate without warning.
I recommend using a chair at the office and saving the stability ball for your core workout at home or at the gym. Before training the core, get some instruction from a certified fitness professional to ensure proper technique.
Whether you choose to use a stability ball or a chair at your desk, adjust the height to meet basic ergonomic guidelines for comfort and safety; for details, check out OSHA.