Editorial: Exercise for NAFLD: does intensity matter?

Currently, there are no established means for the prevention or treatment of non-alcoholic steatohepatitis (NASH) despite our increasing understanding of nonalcoholic fatty liver disease (NAFLD) pathogenesis implicating insulin resistance (IR) as a key factor and highlighting the central role of lipotoxic liver injury in the development of NASH. Lifestyle interventions aiming at decreasing IR and preventing lipotoxicity, including weight loss, diet, and physical exercise, are in the frontline for NASH patient management. Physical activity may ameliorate IR, maintain weight loss, and improve liver histology in NASH patients. However, there are no recognized criteria for the optimal intensity, duration, or total volume of exercise needed to obtain these beneficial effects. In this issue of the American Journal of Gastroenterology, Kistler and colleagues show that vigorous, but not moderate exercise, nor total duration or volume of physical activity, is related to decreased odds of having NASH or advanced fibrosis. Prospective studies using the objective criteria of physical activity, addressing the role of concurrent weight loss, and assessing individual histological features are needed to further clarify the effects of exercise intensity on NAFLD histology.