High-intensity interval training (HIIT), as an individualized exercise training mode based on cardiopulmonary exercise testing (CPET), is characterized by high-intensity training sessions interspersed with short rest periods. The findings from recent trials suggest that in the management of metabolic dysfunction-associated fatty liver disease (MAFLD), compared with traditional aerobic exercise modes such as moderate-intensity continuous training, HIIT may achieve similar or even better effects in reducing liver fat content, increasing peak oxygen uptake, improving insulin resistance, and lowering blood pressure, despite requiring less time commitment and lower energy expenditure. However, there is currently no consensus regarding the formulation of HIIT exercise protocols.

Based on the lower limits of the current mainstream HIIT intensity, sets, and interval time parameters, this study aims to assess the effectiveness, safety, and feasibility of the current exercise prescription in improving MAFLD.

54 Participants aged 35-65 years with MAFLD will be randomized 1:1 to intervention or control. The intervention group will undertake home-based HIIT four times weekly for 8 weeks. Each session comprises 8 cycles with 30-second bouts at 80% peak VO₂ followed by 60-second recoveries at 50% peak VO₂. The control group do not take any types of exercise interventions. Standard care would be provided for both groups.

Inclusion Criteria:

Adults age 35~65 years Nonalcoholic fatty liver diagnosed by abdominal ultrasonography

In conjunction with at least one cardiometabolic risk factor:

• Overweight or Obesity: ≥ 24kg/m2，or waist circumference ≥ 90 cm in men and > 85 cm in women, or excessive body fat mass
• Prediabetes or type 2 diabetes mellitus: HbA1c ≥ 5.7%, or fasting plasma glucose ≥ 6.1mmol/L, or 2-h plasma glucose during OGTT ≥ 7.8mmol/L
• Plasma triglycerides ≥ 1.7 mmol/L (>-150 mg/dl) or lipid-lowering treatment
• HDL-cholesterol ≤ -1.0 mmol/L in men and ≤ -1.3 mmol/L in women or lipid-lowering treatment
• Blood pressure ≥ 130/85 mmHg or treatment for hypertension

Exclusion Criteria:

• Contraindications for Cardiopulmonary Exercise Testing
• The electrocardiogram (ECG) results during cardiopulmonary exercise testing (CPET) showed positive findings
• Receiving GLP-1 receptor agonists, SGLT-2i, or taking >2 antihypertensive/hypoglycemic/lipid-lowering/ antiarrhythmic drugs
• Taking dietary supplements (e.g., fish oil products, over-the-counter diet pills, meal replacements)
• Mental illness
• Other liver diseases
• Movement disorder related diseases and lower limb motor injury in the past 6 months
• Pregnant, lactating or planning to become pregnant in the near future

Only blinding is maintained for data management personnel, laboratory testing personnel, and data analysts, while not applied to subjects and clinical investigators in the clinical trial.