Cardiovascular Autonomic Nervous System Function and Aerobic Capacity in Type 1 Diabetes

Tapio Seppänen,Heikki O. Tikkanen,Juha E. Peltonen,Harriet Hägglund,Mikko Tulppo,Suvi Tiinanen,Jyrki Aho,Anne S. Koponen,Arja Uusitalo

doi:10.3389/fphys.2012.00356

Abstract

Impaired cardiovascular autonomic nervous system (ANS) function has been reported in type 1 diabetes (T1D) patients. ANS function, evaluated by heart rate variability (HRV), systolic blood pressure variability (SBPV), and baroreflex sensitivity (BRS), has been linked to aerobic capacity (VO2peak) in healthy subjects, but this relationship is unknown in T1D. We examined cardiovascular ANS function at rest and during function tests, and its relations to VO2peak in T1D individuals. Ten T1D patients (34 ± 7 years) and 11 healthy control (CON; 31 ± 6 years) age and leisure-time physical activity-matched men were studied. ANS function was recorded at rest and during active standing and handgrip. Determination of VO2peak was obtained with a graded cycle ergometer test. During ANS recordings SBPV, BRS, and resting HRV did not differ between groups, but alpha1 responses to maneuvers in detrended fluctuation analyses were smaller in T1D (active standing; 32%, handgrip; 20%, medians) than in CON (active standing; 71%, handgrip; 54%, p < 0.05). VO2peak was lower in T1D (36 ± 4 ml kg−1 min−1) than in CON (45 ± 9 ml kg−1 min−1, p < 0.05). Resting HRV measures, RMSSD, HF, and SD1 correlated with VO2peak in CON (p < 0.05) and when analyzing groups together. These results suggest that T1D had lower VO2peak, weaker HRV response to maneuvers, but not impaired cardiovascular ANS function at rest compared with CON. Resting parasympathetic cardiac activity correlated with VO2peak in CON but not in T1D. Detrended fluctuation analysis could be a sensitive detector of changes in cardiac ANS function in T1D.

Highlights

The autonomic nervous system (ANS) is a major regulator of the cardiovascular system
Type 1 diabetes patients had lower VO2peak than CON, the groups were matched by the amount of self-reported leisure-time physical activity (LTPA) (Table 1)
Blood pressure, breathing frequency, and time and frequency domain analyses of heart rate variability (HRV) and baroreflex sensitivity (BRS) did not differ between type 1 diabetes (T1D) and CON at rest or during active standing or the handgrip test (Tables 2 and 3)

Summary

Introduction

The autonomic nervous system (ANS) is a major regulator of the cardiovascular system. It regulates heart rate and blood pressure in the short-term to cope with everyday situations. Parasympathetic (vagal) modulation decreases the heart rate and cardiac contractility, whereas activity of the sympathetic branch opposes these effects and regulates peripheral vasoconstriction. Balanced cardiac ANS function is based on strong parasympathetic and efficient, but not overactive, sympathetic modulation of the heart. The relationships between aerobic exercise training or high aerobic capacity and enhanced vagal modulation of the heart have been widely reported, especially in healthy populations (Billman, 2002; Buch et al, 2002; Carter et al, 2003; Hautala et al, 2009). The associations between ANS function and aerobic capacity are not as well known in T1D than in several other populations

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