Department of Sports and Health Management, Jobu University, 634-1 Toyazuka-Machi, Isesaki, Gunma 372-8588, Japan.
Department of Rehabilitation and Movement Science, The University of Vermont, 306 C Rowell, 106 Carrigan Dr, Burlington, VT 05405, USA.
Gait Posture. 2022 Feb;92:123-128. doi: 10.1016/j.gaitpost.2021.11.017. Epub 2021 Nov 18.
Voluntary movement such as lifting a foot in preparation to stepping acts as a self-initiated perturbation that disturbs postural equilibrium. To maintain and restore equilibrium, humans utilize early, anticipatory, and compensatory postural adjustments. Despite technological progress in accessible virtual reality (VR) devices, little is known on the usage of VR in control and maintenance of balance while standing.
How does VR modulate early, anticipatory, and compensatory postural adjustments during a dynamic task of leg lifting while avoiding an obstacle?
First, the postural adjustments in a single-leg obstacle avoidance were compared between real and VR settings, where a statistical reanalysis was performed with data subsets that minimize the difference of foot elevation speed. Second, the effect of simple foot elevation was examined to identify the fundamental nature of leg lifting motion as a self-initiated perturbation. Lastly, perceptual distortion in VR was assessed by evaluating how the spatial scale of the virtual scene used in the single-leg obstacle avoidance experiment was recognized by participants.
The VR setting reduced the activities of lower leg muscles on the supporting side not only in the compensatory phase but also in the preparatory early and anticipatory phases. On the other hand, simple foot elevation resulted in a significant increase of muscle activities with lifting height only found in the compensatory phase. Furthermore, it is suggested that the VR induced perceptual distortion in estimating the sizes of the virtual objects.
The findings provide more definitive evidence that VR presentation modulates the components of postural adjustments for maintaining upright stance while being perturbed. One of the potential psychophysical factors is perceptual distortion in VR, and this provides critical information for further development of VR based training system.
抬脚准备跨步等自主运动是一种自发性扰动，会扰乱姿势平衡。为了维持和恢复平衡，人类会进行早期、预期和代偿性姿势调整。尽管无障碍虚拟现实 (VR) 设备技术取得了进步，但人们对 VR 在站立平衡控制和维持方面的应用知之甚少。
在避免障碍物的动态抬腿任务中，VR 如何调节早期、预期和代偿性姿势调整？
首先，比较了真实和 VR 设置下单腿避障时的姿势调整，对最小化脚抬高速度差异的数据子集进行了统计重分析。其次，检查了简单抬脚的效果，以确定抬腿运动作为自发性扰动的基本性质。最后，通过评估参与者在单腿避障实验中使用的虚拟场景的空间比例如何被识别，来评估 VR 中的感知失真。
VR 设置不仅在代偿阶段，而且在预备早期和预期阶段，都减少了支撑侧小腿肌肉的活动。另一方面，简单抬脚仅在代偿阶段导致肌肉活动随着抬脚高度的显著增加。此外，据推测，VR 会导致对虚拟物体大小的感知失真。
这些发现为 VR 演示调节姿势调整成分以维持直立姿势而不受干扰提供了更确凿的证据。潜在的心理物理因素之一是 VR 中的感知失真，这为进一步开发基于 VR 的训练系统提供了关键信息。
