Rethinking margin of stability: Incorporating step-to-step regulation to resolve the paradox.
Rethinking margin of stability: Incorporating step-to-step regulation to resolve the paradox.
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DOI：
10.1016/j.jbiomech.2022.111334
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发表时间：
2022-11
影响因子：
2.4
通讯作者：
Dingwell, Jonathan B.
中科院分区：
文献类型：
--
作者：
Kazanski, Meghan E.;Cusumano, Joseph P.;Dingwell, Jonathan B.
从倒立摆动力学中衍生出来的中间侧向稳定裕度（）是一种基于机械原理的瞬时稳定性度量。然而，平均测量产生矛盾的结果。步态病理或扰动通常会导致更大（据说“更稳定”）的平均值，尽管有明显的不稳定因素。然而，人们并不“平均”走路-他们一次走一步（有时会失去平衡）。我们断言悖论的出现是因为平均丢弃了一步一步的动态。我们提出了一个框架，统一的倒立摆与目标等效流形（GEM）分析。我们确定在钟摆的质心动力学常数流形，包括一个候选人的“稳定GEM”的目标，以保持一些常数。我们使用这个框架来评估人类在不稳定环境中行走的一步一步的动态。虽然目标相关的偏差很容易纠正，但人类并没有通过允许偏差沿着这个GEM持续存在来利用等同性。因此，保持一个常数与观察到的质心状态的步进波动不一致。相反，参与者调节足部放置波动的程度强烈预测了质心波动的调节。因此，质心动力学可能间接地作为调节中外侧足部放置的结果而出现。为了解决由平均引起的悖论，我们提出了一个新的统计量，不稳定概率（），预测不稳定的可能性。参与者在不稳定时表现出增加（p = 9.45×10−34），尽管表现出更大（“更稳定”）的平均值（p = 1.70×10−15）。因此，正确地捕捉到人们失去横向平衡的风险增加，而平均没有。 这也解释了为什么在不稳定的情况下人们的平均水平会上升。
Derived from inverted pendulum dynamics, mediolateral Margin of Stability () is a mechanically-grounded measure of instantaneous stability. However, average measures yield paradoxical results. Gait pathologies or perturbations often induce larger (supposedly “more stable”) average , despite clearly destabilizing factors. However, people do not walk “on average” – they walk (and sometimes lose balance) one step at a time. We assert the paradox arises because averaging discards step-to-step dynamics. We present a framework unifying the inverted pendulum with Goal-Equivalent Manifold (GEM) analyses. We identify in the pendulum’s center-of-mass dynamics constant- manifolds, including one candidate “stability GEM” signifying the goal to maintain some constant . We used this framework to assess step-to-step dynamics of humans walking in destabilizing environments. While goal-relevant deviations were readily corrected, humans did not exploit equifinality by allowing deviations to persist along this GEM. Thus, maintaining a constant is inconsistent with observed step-to-step fluctuations in center-of-mass states. Conversely, the extent to which participants regulated fluctuations in foot placements strongly predicted regulation of center-of-mass fluctuations. Thus, center-of-mass dynamics may arise indirectly as a consequence of regulating mediolateral foot placements. To resolve the paradox caused by averaging , we present a new statistic, Probability of Instability (), to predict instability likelihood. Participants exhibited increased when destabilized (p = 9.45×10−34), despite exhibiting larger (“more stable”) average (p = 1.70×10−15). Thus, correctly captured people’s increased risk of losing lateral balance, whereas average did not. also explains why peoples’ average increased in destabilizing contexts.
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影响因子：
4.3
作者：
John J;Dingwell JB;Cusumano JP
通讯作者：
Cusumano JP
影响因子：
2.1
作者：
Hof, At L.
通讯作者：
Hof, At L.
影响因子：
2.4
作者：
Beltran, Eduardo J.;Dingwell, Jonathan B.;Wilken, Jason M.
通讯作者：
Wilken, Jason M.
影响因子：
4.6
作者：
Dean, J. C.;Alexander, N. B.;Kuo, A. D.
通讯作者：
Kuo, A. D.
影响因子：
2.4
作者：
Dingwell, Jonathan B.;Cusumano, Joseph P.
通讯作者：
Cusumano, Joseph P.