Nagai N, Moritani T
Laboratory of Applied Physiology, Graduate School of Human and Environmental Studies, Kyoto University, Kyoto, Japan.
Int J Obes Relat Metab Disord. 2004 Jan;28(1):27-33. doi: 10.1038/sj.ijo.0802470.
The autonomic nervous system (ANS) is a key factor in the regulation of energy balance and body fat storage;however, to what extent the physical activity during the childhood years contributes to variations in ANS function is still unclear. The present study was designed to investigate the ANS activity in lean and obese children, focusing on the differences in physical activity levels.
This study was performed on 1080 school children initially recruited to the present study. In all, 24 physically active and 24 inactive obese children (> or =120% of the standard body weight) were chosen as samples. Then, 24 lean-active and 24 lean-inactive children, who were matched individually in age, gender, height, and the amount of sports activity, were carefully selected from the remaining children.
Physical activity was classified as the frequency of participation in after-school sports activities (active; > or =3 times per week, inactive; nothing). The ANS activities were measured during the resting condition by means of heart rate (HR) variability power spectral analysis, which enables us to identify separate frequency components, that is, low frequency (LF; 0.03-0.15 Hz), reflecting mixed sympathetic (SNS) and parasympathetic nervous system (PNS) activity, high frequency (HF; 0.15-0.5 Hz), mainly associated with PNS activity, and total power (TP; 0.03-0.5 Hz), evaluating the overall ANS activity. The spectral powers were log transformed for statistical testing.
The lean-active group demonstrated lower resting HR as well as significantly higher TP, LF, and HF powers compared to the remaining groups. In contrast, the obese-inactive group showed significantly lower TP (P<0.05 vs the remaining groups), LF (P<0.05 vs the lean groups), and HF power (P<0.05 vs the lean groups), respectively. The obese-active and lean-inactive groups were nearly identical in all spectral parameters. The correlation analysis revealed that TP among 48 inactive children was significantly and negatively associated with the percentage of body fat (r=-0.53, P<0.001); however, such correlation among 48 active children was modest (r=-0.33, P=0.02).
Our data suggest that obese children possess reduced sympathetic as well as parasympathetic nervous activities as compared to lean children who have similar physical activity levels. Such autonomic reduction, associated with the amount of body fat in inactive state, might be an etiological factor of onset or development of childhood obesity. On the other hand, regular physical activities could contribute to enhance the overall ANS activity in both lean and obese children. These findings further imply that regular physical activity might be effective in preventing and treating obesity beginning in the childhood.
自主神经系统（ANS）是调节能量平衡和身体脂肪储存的关键因素；然而，儿童时期的身体活动在多大程度上导致自主神经系统功能的变化仍不清楚。本研究旨在调查瘦儿童和肥胖儿童的自主神经系统活动，重点关注身体活动水平的差异。
本研究对最初纳入的1080名学童进行。总共选取了24名身体活跃和24名不活跃的肥胖儿童（体重≥标准体重的120%）作为样本。然后，从其余儿童中精心挑选出24名瘦且活跃和24名瘦且不活跃的儿童，他们在年龄、性别、身高和体育活动量方面进行了个体匹配。
身体活动被分类为参与课外体育活动的频率（活跃；每周≥3次，不活跃；无）。通过心率（HR）变异性功率谱分析在静息状态下测量自主神经系统活动，这使我们能够识别不同的频率成分，即低频（LF；0.03 - 0.15赫兹），反映交感神经（SNS）和副交感神经系统（PNS）的混合活动，高频（HF；0.15 - 0.5赫兹），主要与副交感神经系统活动相关，以及总功率（TP；0.03 - 0.5赫兹），评估自主神经系统的整体活动。对频谱功率进行对数转换以进行统计检验。
与其他组相比，瘦且活跃组的静息心率较低，TP、LF和HF功率显著更高。相比之下，肥胖且不活跃组的TP（与其他组相比，P<0.05）、LF（与瘦组相比，P<0.05）和HF功率（与瘦组相比，P<0.05）分别显著较低。肥胖且活跃组和瘦且不活跃组在所有频谱参数上几乎相同。相关分析显示，48名不活跃儿童的TP与体脂百分比显著负相关（r = -0.53，P<0.001）；然而，48名活跃儿童中的这种相关性较弱（r = -0.33，P = 0.02）。
我们的数据表明，与身体活动水平相似的瘦儿童相比，肥胖儿童的交感神经和副交感神经活动均降低。这种与非活动状态下的体脂量相关的自主神经功能减退可能是儿童肥胖发病或发展的一个病因。另一方面，规律的体育活动可能有助于增强瘦儿童和肥胖儿童的整体自主神经系统活动。这些发现进一步表明，规律的体育活动可能对预防和治疗儿童期肥胖有效。
