Department of Kinesiology, The Pennsylvania State University, University Park, PA 16802, USA.
Department of Engineering Science & Mechanics, The Pennsylvania State University, University Park, PA 16802, USA.
J Biomech. 2023 Nov;160:111836. doi: 10.1016/j.jbiomech.2023.111836. Epub 2023 Oct 13.
Walking humans often navigate complex, varying walking paths. To reduce falls, we must first determine how older adults purposefully vary their steps in contexts that challenge balance. Here, 20 young (21.7±2.6 yrs) and 18 older (71.6±6.0 yrs) healthy adults walked on virtual paths that slowly narrowed (from 45 cm to as narrow as 5 cm). Participants could switch onto an "easier" path whenever they chose. We applied our Goal Equivalent Manifold framework to quantify how participants adjusted their lateral stepping variability and step-to-step corrections of step width and lateral position as these paths narrowed. We also extracted these characteristics at the locations where participants switched paths. As paths narrowed, all participants reduced their lateral stepping variability, but older adults less so. To stay on the narrowing paths, young adults increasingly corrected step-to-step deviations in lateral position more, by correcting step-to-step deviations in step width less. Conversely, as older adults also increasingly corrected lateral position deviations, they did so without sacrificing correcting step-to-step deviations in step width, presumably to preserve balance. While older adults left the narrowing paths sooner, several of their lateral stepping characteristics remained similar to those of younger adults. Older adults largely maintained overall walking performance per se, but they did so by changing how they balanced the competing stepping regulation requirements intrinsic to the task: maintaining position vs. step width. Thus, balancing how to achieve multiple concurrent stepping goals while walking provides older adults the flexibility they need to appropriately adapt their stepping on continuously narrowing walking paths.
行走的人类经常在复杂多变的行走路径中导航。为了减少跌倒，我们首先必须确定老年人在平衡受到挑战的情况下如何有目的地改变他们的步伐。在这里，20 名年轻（21.7±2.6 岁）和 18 名年长（71.6±6.0 岁）健康成年人在虚拟路径上行走，这些路径缓慢变窄（从 45 厘米变窄到 5 厘米）。参与者可以随时选择切换到“更简单”的路径。我们应用我们的目标等效流形框架来量化参与者如何调整他们的横向步幅变异性以及步宽和横向位置的步间校正，因为这些路径变窄。我们还在参与者切换路径的位置提取了这些特征。随着路径变窄，所有参与者都减少了横向步幅变异性，但老年人的减少幅度较小。为了留在变窄的路径上，年轻人通过减少步宽的步间偏差来增加横向位置的步间校正，从而越来越多地校正步间偏差。相反，随着老年人也越来越多地校正横向位置的偏差，他们在不牺牲步宽的步间校正的情况下做到了这一点，大概是为了保持平衡。虽然老年人较早地离开了变窄的路径，但他们的一些横向步幅特征仍与年轻人相似。老年人在很大程度上保持了他们的整体步行性能，但他们通过改变平衡内在任务竞争的步调节要求的方式来实现：保持位置与步宽。因此，平衡如何在行走时实现多个并发的步调节目标为老年人提供了灵活性，使他们能够适当地适应连续变窄的行走路径上的步调节。
