Children's Health and Exercise Research Centre, Sport and Health Sciences, University of Exeter, Exeter EX1 1TX, UK.
Institute of Biomedicine, Kuopio Campus, University of Eastern Finland, FI-70211 Kuopio, Finland.
Int J Environ Res Public Health. 2021 May 18;18(10):5365. doi: 10.3390/ijerph18105365.
Moderate-to-vigorous physical activity (MVPA) positively influences bone mineral content (BMC) in prepubertal children, but it is unknown whether this relationship is partially mediated by free leptin index. The aim of this study was to examine whether the relationship between MVPA and total body less head (TBLH) BMC is mediated or moderated by free leptin index in prepubertal children.
We performed a cross-sectional analysis on 401 children (194 girls) from baseline examinations of the Physical Activity and Nutrition in Childhood Study. We applied the four-way decomposition mediation analysis method to assess whether free leptin index, measured from fasted blood samples, mediated the relationship between accelerometer-measured MVPA and TBLH BMC measured by dual-energy X-ray absorptiometry.
MVPA had a positive controlled direct effect on TBLH BMC in girls and boys (β = 0.010 to 0.011, < 0.05). There was no mediation or interaction between MVPA, free leptin index and TBLH BMC in girls or boys (β = -0.000 to 0.001, > 0.05).
Our study indicates that MVPA positively influences TBLH BMC through pathways not related to free leptin index in predominantly normal-weight prepubertal children, likely primarily through mechanical loading. The relationships between MVPA, free leptin index and TBLH BMC may be influenced by other factors such as pubertal status and adiposity, so it is unknown whether these observations extend to overweight and obese children at different stages of puberty.
中等到剧烈的身体活动（MVPA）对青春期前儿童的骨矿物质含量（BMC）有积极影响，但尚不清楚这种关系是否部分通过游离瘦素指数来介导。本研究旨在检验在青春期前儿童中，MVPA 与全身非头（TBLH）BMC 之间的关系是否通过游离瘦素指数来介导或调节。
我们对来自儿童体力活动与营养研究基线检查的 401 名儿童（194 名女孩）进行了横断面分析。我们应用四向分解中介分析方法来评估游离瘦素指数（从空腹血样中测量）是否在 MVPA（通过加速度计测量）与通过双能 X 射线吸收法测量的 TBLH BMC 之间的关系中起中介作用。
MVPA 对女孩和男孩的 TBLH BMC 有正向的直接影响（β=0.010 至 0.011， <0.05）。在女孩和男孩中，MVPA、游离瘦素指数和 TBLH BMC 之间没有中介或相互作用（β= -0.000 至 0.001， >0.05）。
我们的研究表明，在以正常体重为主的青春期前儿童中，MVPA 通过与游离瘦素指数无关的途径对 TBLH BMC 产生积极影响，这可能主要是通过机械负荷。MVPA、游离瘦素指数和 TBLH BMC 之间的关系可能受到其他因素的影响，如青春期状态和肥胖程度，因此尚不清楚这些观察结果是否适用于不同青春期阶段的超重和肥胖儿童。
