Maintaining stability during perturbed locomotion requires coordinated responses across multiple levels of organization (e.g., legs, joints, muscle-tendon units). However, current approaches to investigating such responses lack a “common currency” that is both shared across scales and can be directly related to perturbation demands. We used mechanical energetics to investigate the demands imposed on a leg by a transient increase in unilateral treadmill belt speed targeted to either early or late stance. We collected full body kinematics and kinetics from 7 healthy participants during 222 total perturbations. From across-subject means, we found early stance perturbations elicited no change in net work exchanged between the perturbed leg and the treadmill but net positive work at the overall leg level, and late stance perturbations elicited positive work at the leg/treadmill interface but no change in net work at the overall leg level. Across all perturbations, changes in ankle and knee work from steady state best reflected changes in overall leg work on the perturbed and contralateral sides, respectively. Broadening this paradigm to include joint level (vs. leg level) perturbations and including muscle-tendon unit mechanical energetics may reveal neuromechanical responses used in destabilizing environments which could inform design of balance-assisting devices and interventions.

中文翻译：

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哪些下肢关节可以补偿人类行走时不稳定的能量？

在扰动运动期间保持稳定性需要跨多个组织级别（例如，腿、关节、肌腱单元）的协调反应。然而，目前调查此类反应的方法缺乏一种“通用货币”，既可以跨尺度共享，又可以与扰动需求直接相关。我们使用机械能量学来研究针对早期或晚期站立的单侧跑步机皮带速度的瞬时增加对腿部的要求。我们在 222 次总扰动期间收集了 7 名健康参与者的全身运动学和动力学。从跨受试者的角度来看，我们发现早期的姿势扰动不会引起扰动腿和跑步机之间交换的净功的变化，但在整个腿水平上的净正功，和后期站姿扰动在腿/跑步机界面引起了积极的工作，但在整体腿水平上没有变化。在所有扰动中，从稳定状态开始脚踝和膝关节功的变化最好地分别反映了受扰侧和对侧整体腿部功的变化。将这种范式扩大到包括关节水平（与腿部水平）的扰动并包括肌肉肌腱单位的机械能量学，可能会揭示在不稳定环境中使用的神经力学反应，这可以为平衡辅助设备和干预措施的设计提供信息。