Exercise training improves cardiovascular autonomic modulation in response to glucose ingestion in obese adults with and without type 2 diabetes mellitus

This study examined the effect of aerobic exercise training on vagal and sympathetic influences on the modulations of heart rate and systolic blood pressure in response to an oral glucose load in obese individuals with and without type 2 diabetes mellitus (T2D). Beat-to-beat arterial pressure and continuous electrocardiogram were measured after a 12-hour overnight fast and in response to glucose ingestion (75 g dextrose) in obese subjects with (T2D group, n = 23) and without (OB group, n = 36) T2D before and after 16 weeks of aerobic exercise training at moderate intensity. Autonomic modulation was assessed using spectral analysis of systolic blood pressure variability (BPV), heart rate variability (HRV), and analysis of baroreflex sensitivity (BRS). Glucose ingestion significantly increased low-frequency (LFSBP), low-frequency HRV (LFRRI), and the ratio of low- to high-frequency components of HRV (LFRRI/HFRRI), and decreased the high-frequency power (HFRRI) <.05). Exercise training increased LFRRI and LFRRI/HFRRI responses, and reduced HFRRI and LFSBP to glucose ingestion in both groups (P <.05), but increased fasted BRS in the OB group only (P <.05); glucose intake had no effect on BRS (P >.05). In conclusion, a 16-week exercise training program improved cardiac autonomic modulation in response to an oral glucose load in obese adults, independently of diabetes status, and in the absence of remarkable changes in body weight, body composition, fitness level, and glycemic control. (C) 2010 Elsevier Inc. All rights reserved.