Undisturbed Stance Control in Healthy Adults Is Achieved Differently Along Anteroposterior and Mediolateral Axes: Evidence From Visual Feedback of Various Signals From Center of Pressure Trajectories

Provided through the screen of a monitor, the participant's resultant center of pressure (CP Res ) movements from a force platform device, modified the postural performance of a healthy individual. However, these effects could largely vary with the axis that researchers consider (mediolateral [ML] or anteroposterior [AP]), because they know these controls are involved in 2 distinct ankle and hip mechanisms. To demonstrate this organization, the author tested a group of healthy adults in several conditions that gave the whole or some part of the information in the CP Res displacements. Compared with the CP Res feedback, left and right plantar CP or body weight distribution feedback deteriorated the control of the vertically projected center of gravity (CG v ) along the ML and AP axes, whose amplitudes increased, respectively. These data highlight the primary role of loading or unloading and pressure variations in the achievement of postural control along each ML or AP axis, respectively. It is interesting that merging these 2 pieces of information (CP Res displacements) helped participants optimize their postural performance.