Body segment parameters for rigid body modelling in biomechanical analyses

In biomechanics, human motion is described as rigid body dynamics due to the complex nature of the human body. During movements, the human body presents many types of deformation, such as stretching, bending, bulging and jiggling, which make precise assessments of physical interactions occurring in the human body extremely difficult. Therefore, for analytical convenience, the human body is often modelled as an inter-linked system of rigid bodies representing body segments. Under the modelled condition, the deformation of each body segment can be neglected, thereby the estimation of kinematic and kinetic phenomena in the human body is much simpler than the reality. Body segment parameters are fundamental inputs for the modelling process and are made up of the segment’s mass, density, centre of mass location and its moment of inertia. There has been a large number of studies quantifying body segment parameters, and the parameters vary one to another depending on the sex, age, ethnic group, and lifestyle of the samples as well as the method used in each study. Thus, it is of great importance for researchers to understand the background of each set of body segment parameters to select a modelling method that best suits their purpose and samples. In this chapter, different methodologies to assess body segment parameters are reviewed with historical and practical perspectives to provide information on the advantages and disadvantages of each set of parameters. Furthermore, to provide examples of the impact of selecting different methods on body segment parameter calculation, we compared several widely used models and discussed their accuracy as a technical report.