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

Abstract

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 (LF(SBP)), low-frequency HRV (LF(RRI)), and the ratio of low- to high-frequency components of HRV (LF(RRI)/HF(RRI)), and decreased the high-frequency power (HF(RRI)) (P < .05). Exercise training increased LF(RRI) and LF(RRI)/HF(RRI) responses, and reduced HF(RRI) and LF(SBP) 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.

Figure 1A-C

Total power (lnTP_RRI, Figure 1A), baroreflex sensitivity (lnBRS, Figure 1B), and high frequency (HF_RRI, Figure 1C) responses (means ± SE) to glucose ingestion before and after exercise training. All values are presented as natural logarithms (ln). ^ap<0.05, pre- vs. post training; ^bp<0.05, OB vs. T2D; ^cp<0.05, fasted vs. glucose loaded; ^dp<0.05, time by group interaction; ^ep<0.05, time by metabolic status interaction

Figure 2A-C

Low frequency power of HRV (LF_RRI, Figure 2A), low frequency to high frequency ratio (lnLF_RRI/HF_RRI, Figure 2B) and low frequency (lnLF_SBP, Figure 2C) responses (means ± SE) to glucose ingestion before and after exercise training. All values are presented as natural logarithms (ln). ^ap<0.05, pre- vs. post training; ^bp<0.05, OB vs. T2D; ^cp<0.05, fasted vs. glucose loaded; ^dp<0.05, time by group interaction; ^ep<0.05, time by metabolic status interaction