No pharmacologic therapies have yet been approved for the treatment of non-alcoholic fatty liver disease (NAFLD) and non-alcoholic steatohepatitis (NASH), its progressive form. Instead, NAFLD is currently managed by lifestyle interventions, including dietary modifications and physical exercise. Despite this, evidence regarding the effect of exercise on NAFLD-associated histological endpoints is lacking.
The aim of this review was to assess the independent effect of exercise on hepatic steatosis, steatohepatitis, and fibrosis, measured by histological assessment or by non-invasive tests (NITs) in patients with biopsy-proven NAFLD.
Nine studies assessing the independent impact of exercise on NAFLD were identified, with six assessing histological endpoints, and five examining NIT outcomes. Two out of the six randomised controlled trials (RCTs) found that exercise did not significantly improve histological endpoints in the absence of weight loss and/or dietary interventions. The remaining four concluded that exercise improved fibrosis and hepatocyte ballooning. However, these studies possessed significant methodological limitations, including self-reported physical activity data, lack of a control group, or non-randomized study design.
Results from the five studies investigating NIT outcomes suggest that exercise improves hepatic steatosis measured by imaging modalities. However, this finding was not continuous for serum biomarkers, which staged NASH and liver fibrosis.
These findings suggest that large and methodologically appropriate RCTs are needed to further investigate exercise’s effect on NAFLD-associated histological endpoints.