Mild-to-moderate intensity exercise improves cardiac autonomic drive in type 2 diabetes

Aims/IntroductionThe aim of the present study was to determine the effect of moderate aerobic exercise on cardiac autonomic function in type 2 diabetic patients. Materials and MethodsHeart rate variability of 20 patients with type 2 diabetes was assessed. Resting electrocardiogram for the heart rate variability analysis at spontaneous respiration was recorded for 5min in the supine position before and after 6months of supervised aerobic training given three times per week. ResultsIn time domain measures, the square root of the mean of the sum of the squares of differences between adjacent R-R intervals (RMSSD; 29.7 [26-34.5] vs 46.4 [29.8-52.2]ms, P=0.023) and the percentage of consecutive RR intervals that differ by more than 50ms (pNN50; 10.7 [5.5-12.7] vs 26.1 [6.6-37.2]%, P=0.025] were significantly increased after exercise. In frequency domain measures, low frequency (62.4 [59.1-79.2] vs 37 [31.3-43.3]nu, P=0.003) and low frequency/high frequency (1.67 [1.44-3.8] vs 0.58 [0.46-0.59]%, P=0.009) were significantly decreased, whereas high frequency (95 [67-149] vs 229 [98-427]ms(2), P=0.006) and high frequency (37.6 [20.8-40.9] vs 63 [56.7-68.7]normalized units, P=0.003) were significantly increased after exercise. In a Poincare plot, standard deviation perpendicular to the line of the Poincare plot (SD1; 21.3 [18.5-24.8]-33.1 [21.5-37.2]ms, P=0.027) was significantly increased after exercise. ConclusionsThese data suggest that three times per week moderate intensity aerobic exercise for 6months improves cardiac rhythm regulation as measured by heart rate variability in type 2 diabetic patients.