Unstable sitting in the workplace--are there physical activity benefits?

The increasingly popular practice of using a stability ball (exercise/fitness ball) as a sitting surface runs counter to conventional human factors/ergonomics guidelines for seated workspace design. Employees sitting on stability balls in an office environment present safety risks that might be justifiable if the practice has a definitive benefit to the promotion of health. However, the published studies and best evidence to date call into question even the theoretical basis for this practice and do not suggest significant health benefits. First, biomechanical studies do not confirm the intended trunk muscle activation. Second, energy expenditure studies show a small (if any) increase in metabolic demand that is unlikely to be effective in combating sedentary work risk factors. Until studies demonstrate more conclusive benefits, the practice of stability ball sitting should be viewed skeptically as a general workplace recommendation in the interest of health or wellness.