Among all patients, aged between 20 and 80 years old, with heart failure (HF) underwent guideline-directed medical therapy (GDMT) in a tertiary care hospital, 40 of them with stable clinical status greater than 4 weeks were sequentially enrolled in the study. Thery were further allocated into the high-intensity interval training (HIIT) and GDMT groups. The 20 HIIT participants underwent additional 36 sessions of exercise training with alternating 80% of peak oxygen consumption (VO2peak) and 40% of VO2peak for 30 mins, whereas the remaining 20 GDMT participants received regular medication treatement. Baseline clinical information was recorded. Cardiopulmonary exercise test (CPET), 2-D echocardiography, bioimpedance analysis, questionnaire for quality of life, serum b-type natriuretic peptide (BNP), circulating microRNA (miRNA) profile and serum metabolomics before intervention were assessed. Cardiomyocytes and/or cardiac fibroblasts were harvested in 10% patient serum for cell activities, western blot, and messenger RNA studies. All the above examinations were followed after completing the exercise training in HIIT participants and 3-4 months after initial visit in GDMT participants. Parametric anslysis was used to assess the differences of continuous parameters with normal distributions. Those without normal distributions were estimated with non-parametric analysis. 2x2 ANOVA was conducted to compare differences of the circulating miRNA between the two groups of participants before and after interventions. Non-continous parameters between the two groups were assessed by chi-square test.