AMANO, M., T. KANDA, H. UE, and T. MORITANI. Exercise training and autonomic nervous system activity in obese individuals. Med. Sci. Sports Exerc., Vol. 33, No. 8, 2001, pp. 1287–1291.
Purpose: This study was designed to investigate the effects of 12 wk of exercise training on autonomic nervous system (ANS) in 18 obese middle-aged men (N = 9) and women (N = 9) (age: 41.6 ± 1.2 yr; BMI: 27.3 ± 0.4 kg·m−2; %fat: 29.6 ± 1.3%, mean ± SE).
Methods: Each subject participated in an aerobic exercise training at anaerobic threshold (AT), consisting of 30 min/session, 3 times/wk, for 12 consecutive weeks. The ANS activities were assessed by means of power spectral analysis of heart rate variability (HRV) at resting condition before, at 5 wk, and after the exercise program.
Results: The exercise training resulted in a significant decrease in body mass, BMI, and % fat (P < 0.01) but not in lean body mass (P > 0.05) together with a significant increase in the AT V̇O2 (P < 0.01). Our power spectral data indicated that there were significant increases in the low-frequency component associated with the sympathovagal activity (0.03–0.15 Hz, 348.5 ± 66.8 vs 694.7 ± 91.5 ms2, P < 0.01), the high-frequency vagal component (0.15-0.4 Hz, 146.3 ± 30.4 vs 347.7 ± 96.5 ms2, P < 0.05), and the overall autonomic activity as evaluated by total power (0.03-0.4 Hz, 494.8 ± 88.5 vs 1042.4 ± 180.9 ms2, P < 0.01) of HRV after the training.
Conclusions: Twelve weeks of exercise training has significantly improved both the sympathetic and parasympathetic nervous activities of the obese individuals with markedly reduced ANS activity, suggesting a possible reversal effect of human ANS functions. These favorable changes may also have an influence on the thermoregulatory control over the obesity.