Department of Child and Adolescent Psychiatry, Psychosomatics and Psychotherapy, University Hospital Essen, University of Duisburg-Essen, Wickenburgstraße 21, 45147 Essen, Germany.
LVR Clinic for Psychosomatic Medicine and Psychotherapy, University of Duisburg-Essen, University Hospital Essen, 45147 Essen, Germany.
BMC Public Health. 2022 May 10;22(1):933. doi: 10.1186/s12889-022-12949-9.
In Sub-Saharan African countries, rapid urbanization and increasing socio-economic status are associated with a transition to decreased physical activity (PA). A more sedentary lifestyle is linked to increased body fat leading to increments in leptin levels. Since rodent and human studies in high-income countries have shown that starvation-induced hypoleptinemia triggers high PA, efforts are warranted to pursue the hypothesis that low leptin levels in lean children of low- and middle-income countries (LMIC) are also associated with high PA.
In this cross-sectional study, we assessed seven-day PA with triaxial accelerometry (ActiGraph GT3X) among 223 primary school children (9 to 12 years of age) in rural Tanzania. Moderate-to-vigorous PA (MVPA) and total accelerometer counts per day were outcome variables. Leptin was determined using enzyme linked immunosorbent assay tests from dried blood spots. Anthropometric assessments were conducted and food insecurity and socio-demographic data were gathered using semi-structured interviews.
In this sample of school children in rural Tanzania, leptin concentrations (median: 0.91 ng/mL, P25: 0.55, P75: 1.69), body mass index z-scores (median: -1.35, P25: -1.93, P75: -0.82), and height-for-age-z-scores (median: -1.16, P25: -1.96, P75: -0.61) were low. In contrast, PA levels were high with a median MVPA time of 119 min/day. Linear regression confirmed that leptin levels were negatively associated with MVPA (beta: -18.1; 95%CI: -29.7; -6.5; p = 0.002) and total accelerometer counts (beta: -90,256; 95%CI: -154,146; -26,365; p = 0.006). Children residing in areas with better infrastructure had lower MVPA levels (p < 0.001) and tended to have higher leptin levels (p = 0.062) than children residing in areas only reachable via dirt roads.
Our cross-sectional field study is the first that supports the hypothesis of low leptin levels as a potential endocrine trigger of high PA in lean children of a LMIC. We observed early signs of a PA transition towards a less active lifestyle in a subgroup residing in areas with better infrastructure that concomitantly tended to have higher leptin concentrations. Considering that area-dependent PA differences were more pronounced among girls than boys, whereas differences in leptin levels were less pronounced, not only biological, but also external factors explain PA transition.
在撒哈拉以南非洲国家，快速的城市化和不断提高的社会经济地位与体力活动（PA）减少有关。久坐不动的生活方式与体脂增加有关，从而导致瘦素水平升高。由于高收入国家的啮齿动物和人类研究表明，饥饿引起的低瘦素血症会引发高 PA，因此有必要努力验证这一假设，即低收入和中等收入国家（LMIC）瘦儿童的低瘦素水平也与高 PA 有关。
在这项横断面研究中，我们使用三轴加速度计（ActiGraph GT3X）评估了坦桑尼亚农村地区 223 名 9 至 12 岁小学生的七天 PA。中等到剧烈的 PA（MVPA）和每天的总加速度计计数是结果变量。使用酶联免疫吸附试验从干血斑中测定瘦素。进行人体测量评估，并使用半结构化访谈收集食物不安全和社会人口统计数据。
在坦桑尼亚农村地区的这组学龄儿童中，瘦素浓度（中位数：0.91ng/mL，P25：0.55，P75：1.69）、体重指数 z 分数（中位数：-1.35，P25：-1.93，P75：-0.82）和身高年龄 z 分数（中位数：-1.16，P25：-1.96，P75：-0.61）较低。相反，PA 水平较高，MVPA 中位数时间为 119 分钟/天。线性回归证实，瘦素水平与 MVPA（β：-18.1；95%CI：-29.7；-6.5；p=0.002）和总加速度计计数（β：-90256；95%CI：-154146；-26365；p=0.006）呈负相关。居住在基础设施较好地区的儿童 MVPA 水平较低（p<0.001），且瘦素水平较高（p=0.062），而居住在仅可通过土路到达地区的儿童则倾向于具有较高的瘦素水平。
我们的横断面实地研究首次支持了低瘦素水平作为低收入和中等收入国家瘦儿童高 PA 的潜在内分泌触发因素的假设。我们观察到，居住在基础设施较好地区的儿童中，PA 向不那么活跃的生活方式转变的早期迹象，同时这些儿童的瘦素浓度也呈上升趋势。考虑到 PA 差异与地理位置有关，而且这种差异在女孩中比男孩更明显，而瘦素水平的差异则不那么明显，这不仅表明存在生物学因素，还表明存在外部因素导致了 PA 的转变。
