Prolonged sitting time as well as reduced physical activity contribute to the prevalence of non-alcoholic fatty liver disease (NAFLD) in a study of middle-aged Koreans. These findings support the importance of both reducing time spent sitting and increasing physical activity, say researchers. Their results are published in the Journal of Hepatology.Physical activity is known to reduce the incidence and mortality of various chronic diseases. However, more than one half of the average person's waking day involves sedentary activities associated with prolonged sitting such as watching TV and using the computer and other devices.