Ludwa Izabella A, Mongeon Kevin, Sanderson Malcolm, Gracia Marco Luis, Klentrou Panagiota
Centre for Bone and Muscle Health, Brock University, St. Catharines, ON L2S 3A1, Canada.
Faculty of Health Sciences, University of Ottawa, Ottawa, ON K1N 6N5, Canada.
Int J Environ Res Public Health. 2021 Mar 18;18(6):3154. doi: 10.3390/ijerph18063154.
This study examines the functional model of bone development in peri-pubertal boys and girls. Specifically, we implemented a mixed-longitudinal design and hierarchical structural models to provide experimental evidence in support of the conceptual functional model of bone development, postulating that the primary mechanical stimulus of bone strength development is muscle force. To this end, we measured radial and tibial bone properties (speed of sound, SOS), isometric grip and knee extensors strength, bone resorption (urinary NTX concentration), body mass index (BMI), somatic maturity (years from peak height velocity) and skeletal maturity (bone age) in 180 children aged 8-16 years. Measurements were repeated 2-4 times over a period of 3 years. The multilevel structural equation modeling of 406 participant-session observations revealed similar results for radial and tibial SOS. Muscle strength (i.e., grip strength for the radial and knee extension for tibial model) and NTX have a significant direct effect on bone SOS (β = 0.29 and -0.18, respectively). Somatic maturity had a direct impact on muscle strength (β = 0.24) and both a direct and indirect effect on bone SOS (total effect, β = 0.30). Physical activity and BMI also had a significant direct impact on bone properties, (β = 0.06 and -0.18, respectively), and an additional significant indirect effect through muscle strength (β = 0.01 and 0.05, respectively) with small differences per bone site and sex. Muscle strength fully mediated the impact of bone age (β = 0.14) while there was no significant effect of energy intake on either muscle strength or bone SOS. In conclusion, our results support the functional model of bone development in that muscle strength and bone metabolism directly affect bone development while the contribution of maturity, physical activity, and other modulators such as BMI, on bone development is additionally modulated through their effect on muscle strength.
本研究考察了青春期前后男孩和女孩骨骼发育的功能模型。具体而言，我们采用了混合纵向设计和分层结构模型，以提供实验证据支持骨骼发育的概念性功能模型，该模型假定骨骼强度发育的主要机械刺激是肌肉力量。为此，我们测量了180名8至16岁儿童的桡骨和胫骨骨骼特性（声速，SOS）、等长握力和膝关节伸肌力量、骨吸收（尿NTX浓度）、体重指数（BMI）、身体成熟度（距身高增长峰值速度的年数）和骨骼成熟度（骨龄）。在3年的时间里重复测量2至4次。对406次参与者-测量时段观察结果进行的多水平结构方程建模显示，桡骨和胫骨SOS的结果相似。肌肉力量（即桡骨模型的握力和胫骨模型的膝关节伸展力）和NTX对骨骼SOS有显著的直接影响（β分别为0.29和-0.18）。身体成熟度对肌肉力量有直接影响（β = 0.24），对骨骼SOS有直接和间接影响（总效应，β = 0.30）。身体活动和BMI对骨骼特性也有显著的直接影响（β分别为0.06和-0.18），并通过肌肉力量产生额外的显著间接影响（β分别为0.01和0.05），每个骨骼部位和性别存在细微差异。肌肉力量完全介导了骨龄的影响（β = 0.14），而能量摄入对肌肉力量或骨骼SOS均无显著影响。总之，我们的结果支持骨骼发育的功能模型，即肌肉力量和骨代谢直接影响骨骼发育，而成熟度、身体活动以及BMI等其他调节因素对骨骼发育的贡献则通过它们对肌肉力量的影响而得到额外调节。
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