The organization of anticipatory postural adjustments

Central control of posture is expressed through anticipatory and compensatory postural adjustments. Anticipatory postural adjustments (APAs) precede planned postural perturbations and minimize them with anticipatory corrections, while compensatory postural adjustments deal with actual perturbations of balance that occur as a result of suboptimal efficiency of anticipatory corrections. The process of generation of APAs is affected by three major factors: expected magnitude and direction of the perturbation voluntary action associated with the perturbation, and postural task. The results of studies investigating the effect of each of these three major factors on APAs while standing, as well as differences in organization of APAs in individuals with pathology, are discussed.