Skeletal muscle and MASLD: Mechanistic and clinical insights.

Metabolic dysfunction-associated steatotic liver disease (MASLD) is intrinsically linked with widespread metabolic perturbations, including within skeletal muscle. Indeed, MASLD is associated with a range of skeletal muscle abnormalities, including insulin resistance, myosteatosis, and sarcopenia, which all converge on the liver to drive disease progression and adverse patient outcomes. This review explores the mechanistic links between skeletal muscle and MASLD, including the role of abnormal glycemic control, systemic inflammation, and disordered myokine signaling. In turn, we discuss how intrinsic liver pathology can feed back to further exacerbate poor skeletal muscle health. Given the central importance of skeletal muscle in MASLD pathogenesis, it offers clinicians an opportunity to intervene for therapeutic benefit. We, therefore, summarize the role of nutrition and physical activity on skeletal muscle mass, quality, and metabolic function and discuss the knock-on effect this has on the liver. An awareness of these treatment strategies is particularly important in the era of effective pharmacological and surgical weight loss interventions, which can be associated with the development of sarcopenia. Finally, we highlight a number of promising drug agents in the clinical trial pipeline that specifically target skeletal muscle in an attempt to improve metabolic and physical functioning.