Effects of Exercise Intervention in Subjects with Metabolic Dysfunction-Associated Steatotic Liver Disease.

Metabolic dysfunction-associated steatotic liver disease (MASLD) is a prevalent liver disorder globally, including in Asia-Pacific countries. In addition to contributing to severe liver disorders, MASLD increases the risk of various complications. Currently, resmetirom is the only U.S. Food and Drug Administration-approved treatment for MASLD-related fibrosis in the United States. Therefore, lifestyle modifications, particularly regular exercise, remain a crucial approach in managing MASLD. Exercise is generally classified into two types: aerobic and resistance. The two forms offer benefits for individuals with MASLD, despite the difference between their effects and underlying mechanisms. Aerobic exercise is accessible, low cost, and promotes high energy expenditure, improving several MASLD-related clinical parameters. However, associated fatigue and discomfort can reduce long-term adherence. Resistance exercise, referring to muscle contractions performed to counteract external resistance, enhances muscle strength, muscle mass, and bone mineral density while also helping to correct metabolic derangement. It is especially suitable for subjects with MASLD who cannot conduct aerobic exercise or have poor cardiorespiratory function. Mechanistically, aerobic exercise enhances insulin sensitivity, while resistance exercise improves metabolic flexibility through adenosine monophosphate-activated protein kinase activation, muscle fiber adaptation, and muscle-liver cross-talk. In terms of aerobic training, traditional moderate-intensity continuous training (MICT) and high-intensity interval training (HIIT) have shown comparable benefits. This review is designed to offer refreshed perspectives on the advantages of exercise, compare the effects and mechanisms of aerobic and resistance exercise, and evaluate the advantages and disadvantages of MICT and HIIT, with emphasis on their impact on hepatic steatosis in subjects with MASLD.