Static versus dynamic predictions of protective stepping following waist-pull perturbations in young and older adults
Static versus dynamic predictions of protective stepping following waist-pull perturbations in young and older adults
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DOI：
10.1016/s0021-9290(98)00124-9
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发表时间：
1998-12-01
影响因子：
2.4
通讯作者：
Hanke, TA
中科院分区：
文献类型：
--
作者：
Pai, YC;Rogers, MW;Hanke, TA
本研究的目的是：(1) 确定不同年龄和跌倒状态的受试者恢复平衡的保护性迈步频率，(2) 比较基于涉及质心 (COM) 位移和速度组合的动态模型（Pai 和 Patron，1997。 Journal of Biomechanics 30, 347-354）的预测迈步与仅基于位移的静态模型与实验诱导迈步的预测。记录了 13 名年轻人、18 名未跌倒的老年者和 18 名老年跌倒者对三种不同幅度的前腰拉力的反应，将运动分析得出的 COM 相平面轨迹与模型预测的迈步阈值进行比较。我们发现，年长的跌倒者进行踏步试验的比例最高（52%），其次是年长的非跌倒者（17.3%），而年轻人（2.7%）的扰动水平最低。在中等水平上，年轻受试者的行走频率低于老年人。每个人都始终处于最高的扰动水平。总体而言，在估计迈步开始方面，动态模型显示出比静态模型（5%）更好的预测能力（65%）。此外，从动态模型导出的步骤启动阈值可以一致地预测何时必须发生步骤。然而，它是有限的，特别是在低扰动水平的老年跌倒者中，因为它认为一些步骤是“不必要的”，这些步骤可能是由害怕跌倒或其他因素引发的。 (C) 1998 Elsevier Science Ltd. 保留所有权利。
The purposes of this study were: (1) to determine the frequency of protective stepping for balance recovery in subjects of different ages and fall-status, and (2) to compare predicted stepping based on a dynamic model (Pai and Patron, 1997. Journal of Biomechanics 30, 347-354) involving displacement and velocity combinations of the center of mass (COM) versus a static model based on displacement alone against experimentally induced stepping. Responses to three different magnitudes of forward waist pulls were recorded for 13 young, 18 older-non-fallers and 18 older-fallers, The COM phase plane trajectories derived from motion analysis were compared with the model-predicted threshold values for stepping. We found that the older fallers had the highest percentage of stepping trials (52%), followed by older-non-fallers (17.3%), and young (2.7%) at the lowest perturbation level. Younger subjects stepped less often than the elderly at the middle level. Everyone consistently stepped at the highest level of perturbation. Overall, the dynamic model showed better predictive capacity (65%) than the static model (5%) for estimating the initiation of stepping. Furthermore, the threshold for step initiation derived from the dynamic model could consistently predict when a step must occur. However, it was limited, especially among older fallers at the low perturbation level, in that it considered some steps 'unnecessary' that were presumably triggered by fear of falling or other factors. (C) 1998 Elsevier Science Ltd. All rights reserved.