Neuromechanical mechanisms of human dynamic stability

在65岁以上的加拿大人中，跌倒和与跌倒有关的伤害的高发生率是一个关键的公共卫生问题。最新数据表明，这一群体约占加拿大人口的15%，但却占所有需要住院治疗的意外跌倒病例的51%，占跌倒总医疗费用的46%。因此，直接和间接医疗保健费用估计分别超过20亿加元和60亿加元。尽管以人口为基础的工作揭示了许多预测跌倒的因素，但老年人中与跌倒相关的住院和受伤的人口标准化率几乎没有变化。有效的平衡控制是主动（避免不稳定）和被动（应对不稳定）控制过程之间复杂关系的结果，这些控制过程受到神经（感觉）和机械（肌肉骨骼）系统的约束。尽管有相当多的临床研究关注老年人的平衡控制和跌倒，但研究全身稳定性控制机制的基础科学研究却很缺乏。拟议的工作将通过三个研究主题产生对人类稳定控制和控制障碍的新见解，这些研究主题迭代地缩小了焦点，从(a)全身动态稳定控制的特征，到(b)神经机械系统特性的实验操作，再到(c)模拟个体肢体和关节水平对动态稳定性的贡献。这项工作将利用互补生物力学方法的组合来检查人类在一系列日常生活活动中的动态稳定性。虽然许多先前的研究已经分别检查了主动和被动稳定性控制，但目前的工作将寻求检查主动和被动控制之间的相互作用，以确定被动控制中的挑战是否可以通过改进的主动控制来抵消。这样的结果将支持基于扰动的训练计划的使用，该计划寻求通过暴露于新的不稳定发作来改善主动控制。考虑到神经和机械系统直接受到生长、衰老和损伤过程的影响，这项工作还将寻求量化神经和机械系统变化导致不稳定性的程度。这项工作的结果将为寻求抵消神经力学缺陷的技术干预的发展提供重要信息。最后，了解个体肢体和关节水平对动态稳定性的贡献为促进更有效的医疗和技术预防跌倒干预措施的发展提供了一个具体的目标。这条研究路线为在此资助期内培训九名本科生和研究生提供了一个框架。

The high incidence of falls and fall-related injuries among Canadians over the age of 65 is a key public health issue. The most current data indicates that this cohort represents approximately 15% of the Canadian population, yet it accounts for 51% of all unintentional fall cases requiring hospitalisation and totals 46% of health care costs for falls. As a result, the direct and indirect healthcare costs have been estimated at over 2 billion and 6 billion Canadian dollars, respectively. Despite population-based work that has revealed numerous factors that are predictive of falls, there has been little change in the population standardised rate of fall-related hospitalisation and injury among older adults. Effective balance control is the result of a complex relationship between proactive (to avoid instability) and reactive (to respond to instability) control processes that are bound by the neural (sensory) and mechanical (musculoskeletal) systems. Notwithstanding considerable clinical research focusing on balance control and falls among older adults, there is a scarcity of basic science research investigating the mechanisms of whole-body stability control. The proposed work will generate novel insights into human stability control and dyscontrol through three research themes that iteratively narrow in focus, moving from (a) a characterisation of whole body dynamic stability control, to (b) experimental manipulation of neuromechanical system properties, to (c) modelling individual-limb and joint-level contributions to dynamic stability.This work will utilise a combination of complementary biomechanical approaches to examine human dynamic stability across a range of activities of daily living. While many previous studies have examined proactive and reactive stability control in isolation, the present work will seek to examine the interaction between proactive and reactive control to determine if challenges in reactive control can be offset by improved proactive control. Such an outcome would support the use of perturbation-based training programs, which seek to improve proactive control through exposure to novel bouts of instability. This work will also seek to quantify the extent to which instability results from alterations to the neural and mechanical systems, given that these systems are directly influenced by growth, ageing and injury processes. Outcomes from this line of work will importantly inform the development of technological interventions seeking to offset neuromechanical deficits. Lastly, understanding individual limb and joint level contributions to dynamic stability provides a specific target to facilitate the development of more effective medical and technological fall prevention interventions. This line of study provides a framework for the training of nine undergraduate and graduate students within this funding period.