Effect of moderate aerobic exercise on sympatho-vagal balance in Type 2 diabetic patients.
OBJECTIVE
The purpose of the study was to determine long-term cardiovascular autonomic adaptation to moderate endurance aerobic exercise in people with Type 2 diabetes in order to test the hypothesis of an enhanced vagal drive.


METHODS
We analysed the power spectral density of heart rate cyclic variations at rest, while lying, and while standing in 12 sedentary, non-smoking, Type 2 diabetic individuals. Testing was performed before and after a 6-month, supervised, progressive, aerobic training programme, twice weekly. Heart rate variability was assessed by autoregressive power spectral analysis (PSA); this method allows reliable quantification of low-frequency (LF) and high-frequency (HF) components, which are considered to be under mainly sympathetic and purely parasympathetic control, respectively.


RESULTS
In 10-min electrocardiogram recordings, mean RR intervals values lying and standing were similar before and after physical exercise. Likewise, total heart rate variability, expressed as total power spectral density (PSD), was not altered by exercise. In contrast, on standing, the HF component, expressed in normalized units, was significantly higher (20.1 +/- 4 vs. 30.4 +/- 5, P < 0.01), whereas the LF component was significantly lower (68.1 +/- 7 vs. 49.8 +/- 8, P < 0.01) after exercise; hence, on standing, the LF/HF ratio, reflecting the sympathetic vs. parasympathetic balance, was markedly lower (16.2 +/- 11 vs. 5.2 +/- 3.2, P = 0.003). No significant exercise-related changes in these PSA components were observed on lying.


CONCLUSIONS
A twice-weekly, 6-month, moderate, aerobic exercise programme, without a concomitant weight loss diet, is associated with significant improvements in cardiovascular autonomic function in overweight, non-smoking, Type 2 diabetic individuals.
Zoppini
G
G
Division of Endocrinology and Metabolic Diseases, University of Verona, Verona and National Research Council, Institute of Bioengineery, Padua, Italy. giacomo.zoppini@univr.it
Cacciatori
V
V
Gemma
M L
ML
Moghetti
P
P
Targher
G
G
Zamboni
C
C
Thomaseth
K
K
Bellavere
F
F
Muggeo
M
M
D000222:Adaptation, Physiological / Q000502:physiology*; D000368:Aged; D001341:Autonomic Nervous System / Q000502:physiology*; D003924:Diabetes Mellitus, Type 2 / Q000628:therapy*; D003925:Diabetic Angiopathies / Q000517:prevention & control; D004562:Electrocardiography; D005081:Exercise Therapy / Q000379:methods*; D005260:Female; D006321:Heart / Q000294:innervation; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011187:Posture / Q000502:physiology; D020421:Vagus Nerve Diseases / Q000517:prevention & control