Abstract
OBJECTIVE: Compare the effects of high-intensity interval training (HIIT) and moderate-intensity continuous training (MICT) on metabolic dysfunction-associated steatotic liver disease (MASLD), focusing on the mechanisms by which these two exercise modalities influence gut microbiota structure, bile acid metabolism, and intestinal barrier function, as well as their regulatory roles in hepatic lipid synthesis and oxidative dynamics. Explore the synergistic effects of exercise-mediated mitochondrial fusion remodeling and leptin signaling, elucidate the causal relationship between gut-derived factors and hepatic metabolic reprogramming, and reveal the potential multi-scale and cross-organ dominant mechanisms of exercise, providing a theoretical basis for systematically comparing the effects of different exercise modalities. METHODS: Thirty-two male rats were randomly divided into NFD (n = 8) and HFD (n = 24) groups and fed normal chow and high-fat chow, respectively. After eight weeks, the HFD group was randomly divided into three groups: (1) MICT-8; (2) HIIT-8; and (3) HFD-8. At the end of the experiment, blood, liver, ileum, and skeletal muscle samples were collected for analysis of the rats' baseline conditions, mitochondrial function, hepatic lipid metabolism, bile acid pathway and gut microbiota, and synthesis of analyses. RESULTS: Both modes of exercise ameliorated metabolic dysregulation and attenuated pathological progression, insulin resistance, and liver fat accumulation in rats with MASLD. Furthermore, both interventions counteracted HFD-induced intestinal barrier dysfunction and restored gut-liver axis homeostasis. HIIT and MICT also upregulated bile acid-related gene expression modulated butyrate-producing bacterial taxa, and adjusted the abundance of butyrate-generating bacteria. CONCLUSION: Both HIIT and MICT improved lipid metabolism in MASLD rats and the difference between the HIIT and MICT groups was not statistically significant. It is noteworthy that HIIT was more effective in improving mitochondrial function in MASLD than MICT (P < 0.001).