Effects of High-Intensity Interval Training Versus Moderate-Intensity Continuous Training on Epicardial Fat Thickness and Endothelial Function in Hypertensive Metabolic Syndrome

Background: Hypertension is common in patients with metabolic syndrome (MS), and it is an important risk factor for cardiovascular-related morbidity and mortality. Compared to moderate-intensity continuous training (MICT), high-intensity interval training (HIIT) is considered a time-efficient exercise strategy for cardiometabolic health. We compared the effects of HIIT and MICT on epicardial fat thickness (EFT) and endothelial function in patients with hypertensive MS. Methods: In total, 34 participants with hypertensive MS (mean age: 50.9 +/- 7.9 years) were randomized to either the HIIT (n = 17) or MICT (n = 17) group. In the HIIT group, participants performed for 3 min at 40% heart-rate reserve (HRR), which was alternated with 3 min at 80% HRR, whereas participants in the MICT group performed at 60% of HRR thrice a week for 8 weeks. EFT was measured with echocardiography, and endothelial function was determined by quantifying endothelial progenitor cells (EPCs), nitric oxide (NO), and flow-mediated dilation (FMD). Results: After exercise training, patients in both the groups showed significantly decreased EFT (P < 0.001 and P < 0.01) and improved FMD (P < 0.001 and P < 0.01). NO (P < 0.05) and EPCs (CD34/KDR, P < 0.01; CD34/CD117, P < 0.05; CD34/CD133, P < 0.05) were significantly improved in the HIIT group, but not in the MICT group. In addition, HIIT had a greater effect than MICT on FMD (group difference, P < 0.05) and EFT (group difference, P < 0.05). Conclusions: Compared to MICT, HIIT seems to better improve FMD and EFT. This finding suggests that HIIT could be more effective than MICT in improving endothelial function in patients with hypertensive MS.