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Neuromuscular Fatigue in Older Adults

老年人的神经肌肉疲劳

基本信息

批准号：
7515713
负责人：
SANDRA K HUNTER
金额：
$ 22.35万
依托单位：
MARQUETTE UNIVERSITY
依托单位国家：
美国
项目类别：
财政年份：
2008
资助国家：
美国
起止时间：
2008-09-30 至 2011-08-31
项目状态：
已结题

项目摘要

DESCRIPTION (provided by applicant): This application examines the cause for age-associated neuromuscular fatigue in tasks that are more functionally relevant to daily activities and that are important for maintenance of independence in old adults within an aging American population. This proposal brings a new and innovative approach to understanding fatigability of the neuromuscular system in old adults by examining functionally relevant tasks that require control of a load with limited limb support and maintenance of power for a dynamic task. Recent studies indicate that older adults experience greater muscle fatigue than young adults during these more functionally relevant tasks. However, the causes of the increase in age-related muscle fatigue in old adults during submaximal dynamic and postural contractions with limited limb support are not understood. Based on preliminary data we hypothesize that neural mechanisms are responsible for greater fatigue exhibited by old adults compared with young adults for submaximal fatiguing contractions that require supporting an inertial load. First, we examine the mechanisms for age-related changes in muscle fatigue of dynamic and postural tasks that involve supporting an inertial load. Specifically, we will compare the time to task failure between young and old adults for a postural isometric and dynamic task and establish the association between the age-related fatigue and functional ability in old adults (Aim 1). We will also determine neural mechanisms that contribute to time to task failure for these tasks in young and old adults (Aim 2). To accomplish Aim 2, we will use transcranial magnetic stimulation to examine corticospinal excitability before, during and after fatigue and this will be quantified as the size of the motor evoked potential normalized to the changes in neuromuscular propagation (M wave). By understanding the magnitude and mechanisms that contribute to age-related fatigue during functionally relevant tasks, we can identify appropriate and simple rehabilitative techniques to improve the increased fatigue experienced by old adults. Our preliminary data suggests that 'practice' of a fatiguing task will improve performance via neural adaptations. Therefore, we will determine the change in time to task failure and corticospinal excitability with practice of a postural isometric and dynamic task performed by young and old adults (Aim 3). This last aim will evaluate the efficacy of 'practice' as a rehabilitative technique, to ameliorate neuromuscular function deficits and minimize impairments in old adults, and also to provide evidence of age-related neural impairments in performance.

描述（由申请人提供）：本申请检查了与日常活动功能相关的任务中与年龄相关的神经肌肉疲劳的原因，这些任务对美国老龄人口中老年人的独立性至关重要。这项建议带来了一个新的和创新的方法来理解疲劳的神经肌肉系统在老年人通过检查功能相关的任务，需要控制的负载与有限的肢体支持和动力的动态任务的维护。最近的研究表明，在这些功能更相关的任务中，老年人比年轻人经历更大的肌肉疲劳。然而，老年人在次最大动态和姿势收缩与有限的肢体支撑期间与年龄相关的肌肉疲劳增加的原因尚不清楚。基于初步的数据，我们假设，神经机制是负责更大的疲劳表现出老年人相比，年轻人的次最大疲劳收缩，需要支持的惯性负荷。首先，我们研究了与年龄相关的动态和姿势任务，包括支持惯性负荷的肌肉疲劳的变化机制。具体而言，我们将比较年轻人和老年人之间的姿势等长和动态任务的任务失败的时间，并建立老年人的年龄相关的疲劳和功能能力之间的关联（目的1）。我们还将确定有助于年轻人和老年人完成这些任务的时间失败的神经机制（目标2）。为了实现目标2，我们将使用经颅磁刺激检查皮质脊髓兴奋性之前，期间和之后的疲劳，这将被量化为运动诱发电位的大小归一化的神经肌肉传播（M波）的变化。通过了解在功能相关任务中导致年龄相关疲劳的程度和机制，我们可以确定适当和简单的康复技术来改善老年人所经历的疲劳增加。我们的初步数据表明，疲劳任务的“实践”将通过神经适应提高性能。因此，我们将通过年轻人和老年人进行的姿势等长和动态任务的练习来确定任务失败时间和皮质脊髓兴奋性的变化（目的3）。这最后一个目标将评估的疗效“实践”作为一种康复技术，以改善神经肌肉功能缺陷，并尽量减少老年人的损伤，并提供证据的年龄相关的神经损伤的性能。