E6 Center of Mass and Body Segments

Title

The human body is modeled as a system of rigid articulated segments. The center of mass (CM) of the system is the point where the resulting gravitational force acts; Its trajectory determines the overall movement of the athlete. In running, the CM describes a vertical undulating path of ~46 cm with each stride. The moment of inertia I of each segment with respect to its own CM and with respect to the body axes determines the resistance to rotation. Steiner's theorem (parallel axes) allows you to calculate the moment of inertia with respect to any axis. In rotational movements (somersaults, jumps with spin) the conservation of angular momentum L = I· explains the acceleration of the spin by reducing I by collecting the segments. Standard segmental models (De Leva, Winter) assign masses and CM positions to each segment as a fraction of body weight, allowing the calculation of global CM and compositional moments of inertia.

ID:459