Chumacero Erik, Yang James, Chagdes James R
Human-Centric Design Research Lab, Department of Mechanical Engineering, Texas Tech University, Lubbock, TX 79409, USA.
Human-Centric Design Research Lab, Department of Mechanical Engineering, Texas Tech University, Lubbock, TX 79409, USA.
J Biomech. 2018 Jun 25;75:77-88. doi: 10.1016/j.jbiomech.2018.04.045. Epub 2018 Jun 1.
To achieve human upright posture (UP) and avoid falls, the central nervous system processes visual, vestibular, and proprioceptive information to activate the appropriate muscles to accelerate or decelerate the body's center of mass. In this process, sensory-motor (SM) latencies and muscular deficits, even in healthy older adults, may cause falls. This condition is worse for people with chronic neuromuscular deficits (stroke survivors, patients with multiple sclerosis or Parkinson's disease). One therapeutic approach is to recover or improve quiet UP by utilizing a balance board (BB) (a rotating surface with a tunable stiffness and time delay), where a patient attempts to maintain UP while task difficulty is manipulated. While BBs are commonly used, it is unclear how UP is maintained or how changes in system parameters such as SM latencies and BB time delay affect UP stability. To understand these questions, it is important that mathematical models be developed with enough degrees-of-freedom to capture the many responses evoked during the maintenance of UP on a BB. This paper presents an ankle-hip model of balance on a BB, which is used to study the combined effect of SM latencies and active muscular stiffness of the ankle and hip joints, and the BB stiffness and time delay on UP stability. The analysis predicts that people with proprioceptive, visual, vestibular loss, or increased SM latencies may show either leaning postures or larger body-sway. The results show that the BB time delay and the visual and vestibular feedback have the largest impact on UP stability.
为了实现人体直立姿势（UP）并避免跌倒，中枢神经系统会处理视觉、前庭和本体感觉信息，以激活适当的肌肉来加速或减速身体的质心。在此过程中，即使是健康的老年人，感觉运动（SM）潜伏期和肌肉功能缺陷也可能导致跌倒。对于患有慢性神经肌肉缺陷的人（中风幸存者、多发性硬化症或帕金森病患者），这种情况会更糟。一种治疗方法是通过使用平衡板（BB）（一种具有可调刚度和时间延迟的旋转表面）来恢复或改善安静直立姿势，患者在平衡板上尝试保持直立姿势的同时，任务难度会受到控制。虽然平衡板被广泛使用，但尚不清楚如何维持直立姿势，也不清楚系统参数的变化（如SM潜伏期和平衡板时间延迟）如何影响直立姿势的稳定性。为了理解这些问题，开发具有足够自由度的数学模型以捕捉在平衡板上维持直立姿势期间引发的多种反应非常重要。本文提出了一种在平衡板上的脚踝 - 髋关节平衡模型，用于研究SM潜伏期以及脚踝和髋关节的主动肌肉刚度、平衡板刚度和时间延迟对直立姿势稳定性的综合影响。分析预测，患有本体感觉、视觉、前庭功能丧失或SM潜伏期增加的人可能会表现出倾斜姿势或更大的身体摆动。结果表明，平衡板时间延迟以及视觉和前庭反馈对直立姿势稳定性的影响最大。
