Self‐Directed High‐Intensity Interval Versus Moderate Continuous Training on Cardiometabolic Health in Metabolic Dysfunction‐Associated Steatotic Liver Disease: A Randomized Controlled Trial

ABSTRACT Exercise is recommended for metabolic dysfunction‐associated steatotic liver disease (MASLD, previously known as nonalcoholic fatty liver disease [NAFLD]), but the optimal exercise mode remains unclear. We compared high‐intensity interval training (HIIT) versus moderate‐intensity continuous training (MCT) on cardiorespiratory fitness in patients with MASLD. This randomized trial assigned patients with ultrasonography‐confirmed NAFLD/MASLD to HIIT ( n = 46) or MCT ( n = 49) for 24 weeks; a non‐randomized observation group (OBS; n = 20) was also recruited. Both exercise groups performed self‐directed treadmill training thrice weekly in free‐living settings (home, residential gyms, or community fitness facilities). HIIT: 5 cycles of 4‐min intervals at 80%–90% peak oxygen consumption (V̇O 2peak ) with 3‐min recovery at 50% V̇O 2peak . MCT: 30–40 min at 60% V̇O 2peak . Outcomes were assessed at baseline and week 24. Both HIIT and MCT significantly reduced hepatic steatosis versus OBS (both p < 0.05), with no between‐group difference. HIIT achieved greater V̇O 2peak improvements than MCT and OBS ( p < 0.05). Both exercise groups increased minute ventilation and carbohydrate utilization at moderate‐to‐high intensities versus OBS ( p < 0.05). HIIT and MCT equally reduce hepatic steatosis in patients with MASLD, suggesting exercise participation matters more than intensity for liver fat reduction. Importantly, HIIT provides superior cardiorespiratory benefits. Trial Registration: ClinicalTrials.gov (NCT04463667)