Author(s): LANNOY, C., BIOURGE, L., CALVO-BLANCO, S., FACHE, L., LECLERCQ, I.A., DELDICQUE, L., Institution: UNIVERSITÉ CATHOLIQUE DE LOUVAIN, Country: BELGIUM, Abstract-ID: 2469

INTRODUCTION:
Metabolic dysfunction-associated steatotic liver disease (MASLD) is defined as excessive triglyceride storage in the liver combined with the presence of at least one cardiometabolic risk factor and the absence of alcohol abuse (1). Recently, myosteatosis, defined as excessive lipid storage in skeletal muscle, has been shown to be linked to the severity of MASLD in preclinical models (2). In literature, moderate intensity continuous training (MCT) and high intensity interval training (HIIT) both improve hepatic steatosis but poor data are available about their respective effect on myosteatosis associated and the mechanisms involved (2,3). This study aims to investigate if physical exercise could reduce myosteatosis and the severity of MASLD in a preclinical model, and which training modality would be the most effective.
METHODS:
Fat Aussie (FOZ) mice fed a high fat diet (HFD) and C57BL6/J mice fed a Western diet with 30% fructose in drinking water (WDF) for 20 weeks were used as preclinical models of MASLD. Each model was divided into five groups: treadmill control (CTRL_TM; FOZ n=10,C57 n=8), MCT (FOZ n=7, C57 n=8), HIIT (FOZ n=9, C57 n=8), wheel control (CTRL_W; FOZ n=6, C57 n=8), and voluntary wheel running (W; FOZ n=6, C57 n=8). After 12 weeks of diet, mice were trained 5 times per week for 8 weeks on a treadmill or during nights on the wheel. Before and after training, weight, body composition and density of the dorsal muscle (DM) and the liver were measured. Mice were sacrificed at the end of training period. Hindlimb muscles and liver were collected for further analysis.
RESULTS:
Exercise interventions induced model-dependent responses. While MCT improved body weight and composition in both models, HIIT and voluntary training had no effect on these outcomes in FOZ mice. In contrast, in C57 mice, all exercise modalities significantly affected weight gain and fat and lean mass proportions. Myosteatosis was not improved by MCT or HIIT; however, voluntary running prevented its increase in FOZ mice compared with CTRL_W. Hepatic steatosis was reduced only in C57 mice following voluntary running.
CONCLUSION:
Although HIIT and MCT improved body composition, their effect on improving MASLD and myosteatosis in mice models with severe form of MASLD were limited without changing diet. However, voluntary running showed improvement, notably regarding hepatic steatosis. Further analyses are needed to investigate mechanisms implied through fat infiltration in liver and skeletal muscle and crosstalk communication between these two organs.

References:
1. Tacke et al., J. Hepatol. 2024
2. Henin et al., JHEP Rep. 2024
3. Liu et al., J. Obes. Metab. Syndr. 2025