Precision of the estimation of human limb inertial parameters

Repeat measurements were made by 2 operators on a group of 50 physically ac tive subjects (age, 20.7 years +/- 1.8; males: height 1.780 m +/- 0.043, ma ss, 78.09 kg +/- 9.30; females: height, 1.680 m +/- 0.064, mass, 66.67 kg /- 6.67) to determine the precision with which the subjects' limb segment i nertial parameters could be estimated. Segmental inertial parameters were d etermined using 3 techniques, 2 of which involved modeling segments as geom etric solids, and a 3rd which used the equations of Zatsiorsky et al. (1990 ). Precisions were high for all 3 techniques, with little difference betwee n inter- and intra-operator precisions. The lowest precisions were obtained for the hands and feet. For these segments the use of repeat measures to i mprove precision is recommended. These results imply that with similarly tr ained measurers, comparison of inertial parameters determined using the sam e protocol but obtained by different operators is appropriate, and that it is viable to have 2 measurers taking measurements on the same subject to ac celerate data collection.