Intersection of ground reaction force vectors during human locomotion

Human gait and its stabilization is a complex task, even though it is ubiquitous in everyday life and not consciously controlled by most people. Thus, basic stabilization mechanisms are used. Previous research suggests that the virtual pendulum concept maintains the upright position when walking over a level surface, stabilizing the body like a physical pendulum. The concept assumes that the ground reaction forces intersect at a point above the body's center of mass, the virtual pivot point. However, it is unclear whether the virtual pendulum concept is also used for perturbations such as walking over uneven ground or walking with altered posture. Furthermore, previous studies lack the exact distinction between single and double supported stance phases of walking. Additionally, the literature considers almost exclusively the virtual pivot point during walking, and not during running. Therefore, several experiments were conducted for this thesis to address the aforementioned ambiguities. It was observed that in walking over visible and camouflaged curbs the ground reaction forces pointed predominantly to the vicinity of a point above the center of mass. The deviations from the point were small. In other experiments it was found that in the double support phase, the ground reaction forces pointed with a small spread into the center of mass. In running experiments it could be shown that the ground reaction forces pointed with a small spread below the center of mass.