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Anticipatory and compensatory postural adjustments(APAs and CPAs,respectively)are two main types of adjustment to maintain and restore upright balance in the case of external perturbation.The purpose of this study was to explore APAs and CPAs in response to support surface translations as a window into neural control strategies of postural preparation to action/perturbation.Eight healthy young subjects were required to make a step in response to support-surface perturbations.The postural perturbations consisted of 5-cm forward translations of the force plate under the subjects feet,with peak ramp velocities of 5 cm/s,and peak accelerations of 0.05 g.Sagittal plane balance was perturbed at random intervals by the movable platform in the forward direction.The signals from the force platform and accelerator were digitized at the sampling frequency of 1500 Hz.Postural adjustments were compared from center of pressure(COP)and from acceleration of the trunk at the center of mass(COM)level(L5)in the anterior-posterior(AP)direction within the time intervals typical of APAs and CPAs.Ours results showed that the anticipatory displacement of the COP was smaller and compensatory COP displacement was larger during preparation to making a step associated with support surface translations.These findings highlight the importance of investigating the strategies in response to support surface translations in maintaining control of vertical posture.The results reported here could have clinical relevance to identify the risk of making a step that has been linked to an increased risk of falls among the elderly people.