The segment principal moments of inertia of a sample of 7 elderly males and 12 elderly females were estimated using a model based on stacked elliptical cylinders at 2-cm intervals. Apart from the thigh, all male parameters were larger than female parameters. The largest differences were for the lower trunk and hand and for the forearm. The inertia parameters of the thigh for the males were about 12% smaller than the females. Nonlinear estimations of segment principal moments were then determined. The effect of the differences was tested by cross validating cadaver results against the elliptical model results. The regressions were then cross validated using an independent sample of 6 subjects. The standard errors of fit given as a percentage of the mean, Sf, were smaller than the cross validation results for the cadaver regressions and the differences were attributed to differences between cadavers and living subjects.
Robert K. Jensen and Paula Fletcher are with the Centre for Research in Human Development and School of Human Movement, Laurentian University, Sudbury, ON, Canada P3E 2C6.