Head and Trunk Segment Moments of Inertia Estimation Using Angular Momentum Technique: Validity and Sensitivity Analysis

Classical models to estimate the head and trunk (HT) moments of inertia (I) are limited to populations from which the anthropometric measures were obtained. The purposes of this study were to determine if the angular momentum technique can be used to estimate subject-specific HT´s I values and test its validity and sensitivity. Twenty-three adults who participated in this study were divided into three morphological groups according to their body mass index (BMI). Using the proposed technique, the HT´s I values were estimated for the whole sample and compared to three well-known methods to test its validity. The sensitivity of the proposed method was verified while applied to individuals with different BMI (i.e., lean, normal, and obese). The angular momentum technique gave I values within the range of those of the three methods for the entire sample. Statistical differences were identified between the lean and obese groups in relative radii of gyration for the anteroposterior and mediolateral axes (P <; 0.05). Since the proposed technique makes no assumption on the mass distribution and segments´ geometry, it appeared to be more sensitive to body morphology changes in estimating the HT´s I values in lean and obese subjects compared to the classical methods.