SEGMENT INERTIAL PARAMETER EVALUATION IN 2 ANTHROPOMETRIC MODELS BY APPLICATION OF A DYNAMIC LINKED SEGMENT MODEL

The estimation of segment inertial parameters (SIPs) is an important s ource of error in inverse dynamic analysis. In most individual cases S IPs are derived from extrapolation of known SIPs of a certain populati on through regression equations (proportional models). Another well-kn own method is the use of mathematical approximation of the shape of hu man body segments combined with estimations of segment densities (geom etric models). In the current study five males and five females perfor med four different lifting movements in the sagittal plane. A full bod y linked segment model was applied twice to the same data set, once us ing a proportional and once using a geometric anthropometric model. As a full body linked segment model is an overdetermined system of equat ions, four equations could be formed to test the summed effect of SIP errors on the inverse dynamic analysis. The overall performance in ter ms of coefficients of correlation was better for the geometric model a s compared to the proportional model. When a back lifting movement was performed, the equations indicated systematic errors in the proportio nal model. However, when a leg lifting movement was performed, the equ ations indicated systematic errors in the geometric model. Therefore, analyzing only one kind of movement does not suffice to draw conclusio ns with respect to the reliability of an anthropometric model.