Combined moderate and high intensity exercise with dietary restriction improves cardiac autonomic function associated with a reduction in central and systemic arterial stiffness in obese adults: a clinical trial

OBJECTIVE The present study aimed to assess the effects of exercise with dietary restriction on cardiac autonomic activity, arterial stiffness, and cardiovascular biomarkers in obese individuals. METHODS Seventeen obese adults completed an 8-week exercise and dietary program. Anthropometry, body composition, and multiple biochemical markers were measured. We used carotid-femoral pulse wave velocity (cfPWV), brachial-ankle pulse wave velocity (baPWV), central blood pressure, and augmentation index (AIx) to assess arterial stiffness. To determine cardiac autonomic activity, heart rate variability (HRV) was analyzed by standard deviation of normal-to-normal intervals (SDNN), square root of the mean squared differences of successive normal-to-normal intervals (RMSSD), total power (TF), low-frequency power in normalized units (LFnu), high-frequency power in normalized units (HFnu), and low-frequency power/high-frequency power (LF/HF). RESULTS Following the exercise and diet intervention, obese subjects had significant reductions in body weight, body mass index, body fat percentage, brachial systolic blood pressure, and resting heart rate, and they had shown improvements in blood chemistry markers such as lipid profiles, insulin, and high-sensitivity C-reactive protein. There was a significant reduction in both cfPWV and baPWV following the intervention when compared to baseline levels. Moreover, the AIx and aortic systolic blood pressure were significantly reduced after the intervention. The diet and exercise intervention significantly increased cardiac autonomic modulation (determined by improved SDNN, RMSSD, TP LF, HF, and LF/HF), which was partly due to changes in heart rate, insulin resistance, and the inflammatory pattern. Furthermore, we observed a correlation between enhanced cardiac autonomic modulation (LF/HF) and decreased arterial stiffness, as measured by central cfPWV and systemic baPWV. DISCUSSION An 8-week combined intervention of diet and exercise is effective in improving cardiac autonomic function in obese adults, with an associated decrease in central and systemic arterial stiffness.