The Optimal Control of Human Standing Posture

Human erect posture has turned postural stability control into a key determinant of human motor behavior. The process of postural control can be simplified to the maintenance of the body's center of gravity (COG) within the base of support (BOS). In such a biomechanical model, the central COG position within the BOS and minimized movement-related disturbances are symptomatic of optimal stability. The postural stability control and its optimization are shaped during ontogenetic development and achieve their optimum in adolescents. To assess the optimal postural stability, a group of 100 young (50 females and 50 males), healthy, and able-bodied subjects participated in the study. The assessment of their postural stability was based on trajectories of the COG oscillations during ten 60-s quiet standing trials with and without visual input. The observed COG oscillations remained within 10 mm and 2 mm in anteroposterior (AP) and mediolateral (ML) planes, respectively. The COG oscillations significantly correlated with individual body anthropometry and the size of the base of support. The findings of this novel analysis of postural sway can be used as a reference for diagnostic purposes, particularly in age-related changes of postural stability and neuromuscular disorders.