Jensen R K, Nassas G
Centre for Research in Human Development, Laurentian University, Sudbury, Ontario, Canada.
Med Sci Sports Exerc. 1988 Dec;20(6):594-604.
Although there have been numerous studies of the moments of inertia of the body segments using a variety of the techniques, few have reported the principal moments and none has considered the changes in the principal moments during childhood and adolescence. The purpose of this study was to use a mathematical model to determine the intraindividual changes and interindividual differences in the segment principal moments during growth. The body was modelled as 15 segments and composed of transverse elliptical zones of known density. Moments and products of inertia about the segment mass centroid were calculated and the principal moments and axes determined from the ellipsoid of inertia. A mixed longitudinal study of 12 boys over 9 yr for a total of 88 annual recordings covering the age range 4 to 20 yr was conducted. Polynomial regressions fitted to the intraindividual changes showed a similarity in the curves to 10 yr followed by a wide divergence of growth patterns. The changes in the principal moments across age follow the principles of cephalocaudad and distal to proximal development for all three axes. These changes are more accentuated than the changes for segment length, volume, or mass. The results were consistent with principal moments reported for cadavers and young male adult gamma radiation scans as well as estimates based on simplified models of the segments. The magnitude of the changes in principal moments with age makes it essential that appropriate parameters be used in the analysis or simulation of the movements of children and adolescents.
尽管已经使用多种技术对身体各节段的转动惯量进行了大量研究，但很少有研究报告主转动惯量，而且没有一项研究考虑过儿童期和青少年期主转动惯量的变化。本研究的目的是使用数学模型来确定生长过程中各节段主转动惯量的个体内变化和个体间差异。将身体建模为15个节段，并由已知密度的横向椭圆区域组成。计算了关于节段质心的转动惯量和惯性积，并从惯性椭球体确定了主转动惯量和轴。对12名男孩进行了为期9年的混合纵向研究，共进行了88次年度记录，涵盖4至20岁的年龄范围。拟合个体内变化的多项式回归显示，曲线在10岁之前具有相似性，随后生长模式出现广泛差异。所有三个轴上主转动惯量随年龄的变化遵循头尾和近端到远端的发育原则。这些变化比节段长度、体积或质量的变化更为明显。结果与尸体和年轻男性成人伽马射线扫描报告的主转动惯量以及基于节段简化模型的估计结果一致。主转动惯量随年龄变化的幅度使得在分析或模拟儿童和青少年的运动时必须使用适当的参数。
