Table_1_Balance Adaptation While Standing on a Compliant Base Depends on the Current Sensory Condition in Healthy Young Adults.DOCX

BackgroundSeveral investigations have addressed the process of balance adaptation to external perturbations. The adaptation during unperturbed stance has received little attention. Further, whether the current sensory conditions affect the adaptation rate has not been established. We have addressed the role of vision and haptic feedback on adaptation while standing on foam.MethodsIn 22 young subjects, the analysis of geometric (path length and sway area) and spectral variables (median frequency and mean level of both total spectrum and selected frequency windows) of the oscillation of the centre of feet pressure (CoP) identified the effects of vision, light-touch (LT) or both in the anteroposterior (AP) and mediolateral (ML) direction over 8 consecutive 90 s standing trials.ResultsAdaptation was obvious without vision (eyes closed; EC) and tenuous with vision (eyes open; EO). With trial repetition, path length and median frequency diminished with EC (p < 0.001) while sway area and mean level of the spectrum increased (p < 0.001). The low- and high-frequency range of the spectrum increased and decreased in AP and ML directions, respectively. Touch compared to no-touch enhanced the rate of increase of the low-frequency power (p < 0.05). Spectral differences in distinct sensory conditions persisted after adaptation.ConclusionBalance adaptation occurs during standing on foam. Adaptation leads to a progressive increase in the amplitude of the lowest frequencies of the spectrum and a concurrent decrease in the high-frequency range. Within this common behaviour, touch adds to its stabilising action a modest effect on the adaptation rate. Stabilisation is improved by favouring slow oscillations at the expense of sway minimisation. These findings are preliminary to investigations of balance problems in persons with sensory deficits, ageing, and peripheral or central nervous lesion.

背景：众多研究已探讨对外部干扰的平衡适应过程。然而，在无干扰站立状态下的适应过程却鲜受关注。此外，当前感觉条件是否影响适应速率尚未得到明确。本研究旨在探讨在泡沫上站立时，视觉和触觉反馈对适应过程的作用。方法：在22名年轻受试者中，通过分析足底压力中心（CoP）振荡的几何变量（路径长度和摇摆面积）以及光谱变量（中频和总光谱及选定频率窗口的平均水平），确定了视觉、轻触（LT）或两者在前后（AP）和内外（ML）方向上对连续8次90秒站立试验的影响。结果：在无视觉（闭眼；EC）的情况下，适应明显；在有视觉（睁眼；EO）的情况下，适应则显得薄弱。随着试验的重复，路径长度和中频在EC条件下减少（p < 0.001），而摇摆面积和光谱的平均水平增加（p < 0.001）。在AP和ML方向上，光谱的低频和高频范围分别增加和减少。与无触觉相比，触觉增强了低频功率增加的速率（p < 0.05）。在不同感觉条件下，光谱差异在适应后仍然持续。结论：在泡沫上站立时，平衡适应会发生。适应导致光谱最低频率幅度的渐进增加和同时高频范围的减少。在此共同行为中，触觉在稳定作用的基础上，对适应速率产生了一定的微小影响。通过牺牲摇摆最小化，优先考虑慢振荡，稳定性得以提升。这些发现为探讨具有感觉缺陷、衰老、周围或中枢神经系统损伤者的平衡问题提供了初步的研究基础。