Data from: Postural stability margins as a function of support surface slopes

This investigation examined the effects of slope of the surface of support (35°, 30°, 20°, 10° Facing(Toe) Down, 0° Flat and 10°, 20°, 25° Facing (Toe) Up) and postural orientation on the margins of postural stability in quiet standing of young adults. The findings showed that the center of pressure—CoP (displacement, area and length) had least motion at the baseline (0° Flat) platform condition that progressively increased as a function of platform angle in both facing up and down directions. The virtual time to collision (VTC) dynamics revealed that the spatio-temporal margins to the functional stability boundary were progressively smaller and the VTC time series also more regular (SampEn–Sample Entropy) as slope angle increased. Surface slope induces a restricted stability region with lower dimension VTC dynamics that is more constrained when postural orientation is facing down the slope. These findings provide further evidence that VTC acts as a control variable in standing posture that is influenced by the emergent dynamics of the individual-environment-task interaction.

本研究考察了支撑面坡度与身体姿势朝向对青年人群静立姿势下姿势稳定性边界裕度的影响，其中支撑面坡度设置为35°、30°、20°、10°足尖朝下、0°水平平台，以及10°、20°、25°足尖朝上。研究结果显示，压力中心（center of pressure，CoP）的位移、覆盖面积与轨迹长度指标，在基线条件（0°水平平台）下的活动度最低；且在足尖朝上和朝下两种朝向中，该指标的活动度均随支撑面坡度的增大而逐步提升。虚拟碰撞时间（virtual time to collision，VTC）动力学分析表明，随着坡度增大，与姿势功能稳定性边界对应的时空裕度逐步缩小，且VTC时间序列的规律性也随之增强（SampEn——样本熵，Sample Entropy）。支撑面坡度会导致姿势稳定性区域受限，此时VTC动力学的维度更低；且当身体朝向坡下时，该约束效应更为显著。本研究结果进一步证实，VTC可作为静立姿势的控制变量，其变化受个体-环境-任务交互的涌现动力学特性影响。