INSTABILITY AND MUSCULAR DEMAND DURING OBSTACLE CROSSING

越障过程中的不稳定和肌肉需求

• 批准号: 6611932
• 负责人: LI-SHAN CHOU
• 金额: $ 7.12万
• 依托单位: UNIVERSITY OF OREGON
• 依托单位国家: 美国
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-04-04 至 2005-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6611932
• 关键词: accident proneness; accidental falls; aging; balance; biomechanics; clinical research; computer simulation; electromyography; environment; gait; human old age (65+); human subject; muscle strength; neuromuscular function; patient oriented research; technology /technique development

DESCRIPTION (provided by applicant): Falls are among the most serious problems facing the aging population and have become the largest single cause of accidental death. Moreover, the total direct cost of fall injuries in 1994 among people 65 and older was $20.2 billion. Most falls in the elderly stem from interactions between environmental hazards and increased individual susceptibility to hazards from accumulated effects of age and intrinsic factors. Research on biomechanics of selected physical tasks, that take both environmental and intrinsic factors into account, is needed to quantify impairment magnitudes, to determine what elements are critical to the impairment, and ultimately to design more effective interventions for preventing falls in the elderly. The long-term goals of this proposed project are to advance the understanding of the mechanisms underlying the increased incidence of falls in the elderly, to determine a more effective method of identifying aged persons at risk of falling, and eventually to design more effective exercise/strengthening programs for the prevention of falls in the elderly. Specific aims of this project are to (1) demonstrate that motion of the whole body center of mass (COM) during obstacle crossing could better distinguish fallers from non-fallers when compared to individual segmental motion, (2) examine the relationship between ability to accommodate to environmental hazards during locomotion and muscle weakness, and (3) to identify quantitative, biomechanical indices (muscular demand-to-capacity ratios) that can better indicate the level of mechanical challenge imposed on selected muscles. Motion analysis and muscle strength testing will be performed on 24 elderly non-fallers and 24 elderly fallers (65 years or older). Body segment motion, ground reaction forces, and electromyography will be collected during unobstructed walking and stepping over obstacles of heights corresponding to 2.5% and 10% of each subject's height. Isometric strength of selected lower extremity muscles will be measured bilaterally. A thirteen-link biomechanical model, with kinematic inputs of each body segment and ground reaction forces will be used to compute the three-dimensional motion of the whole body COM and three-dimensional joint moments (torques) of the lower limbs. Data analysis will be performed on both mechanical and neuromuscular levels, including the isometric muscle strength, electromyography, motion of the COM, and it's interaction with the center of pressure (COP) of the stance foot derived from ground reaction forces and moments. Finally, correlation between muscle strength and dynamic balance control (indicated by the motion of the whole body COM) will be examined. This proposed project is expected to identify/define more sensitive biomechanical measures (both intrinsic and extrinsic) for better quantification of age-related mobility impairment and functional challenges imposed on our musculoskeletal system.

描述（申请人提供）：跌倒是人口老龄化面临的最严重问题之一，已成为意外死亡的最大单一原因。此外，1994 年 65 岁及以上老年人跌倒受伤的直接损失总额为 202 亿美元。大多数老年人跌倒是由于环境危害与年龄和内在因素累积影响导致的个人对危害的易感性增加之间的相互作用造成的。需要对选定的身体任务的生物力学进行研究，同时考虑环境和内在因素，以量化损伤程度，确定哪些因素对损伤至关重要，并最终设计出更有效的干预措施来预防老年人跌倒。该项目的长期目标是加深对老年人跌倒发生率增加的机制的理解，确定一种更有效的方法来识别有跌倒风险的老年人，并最终设计出更有效的运动/加强预防老年人跌倒的计划。该项目的具体目标是（1）证明与个体节段运动相比，越障过程中全身质心（COM）的运动可以更好地区分跌倒者与非跌倒者，（2）检查越障过程中跌倒者和非跌倒者的运动之间的关系。适应运动过程中的环境危害和肌肉无力，以及（3）确定定量的生物力学指数（肌肉需求与能力的比率），可以更好地表明对选定肌肉施加的机械挑战的水平。将对 24 名未跌倒的老年患者和 24 名老年跌倒者（65 岁或以上）进行运动分析和肌肉力量测试。在无障碍行走和跨越高度分别为每个受试者身高的 2.5% 和 10% 的障碍物期间，将收集身体节段运动、地面反作用力和肌电图。 将测量选定下肢肌肉的双侧等长肌力。 十三连杆生物力学模型，具有每个身体部分的运动学输入和地面反作用力，将用于计算整个身体 COM 的三维运动和下肢的三维关节力矩（扭矩）。数据分析将在机械和神经肌肉层面进行，包括等长肌肉力量、肌电图、COM 运动，以及它与源自地面反作用力和力矩的站立脚压力中心 (COP) 的相互作用。最后，将检查肌肉力量和动态平衡控制（由全身 COM 的运动表示）之间的相关性。该拟议项目预计将确定/定义更敏感的生物力学测量（内在和外在），以更好地量化与年龄相关的活动障碍和对我们的肌肉骨骼系统造成的功能挑战。