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）：本申请研究了与日常活动功能更重要的任务中与年龄相关的神经肌肉疲劳的原因，这对于维持美国老年人群中老年人的独立性很重要。该提案通过检查与功能相关的任务，需要控制有限的肢体支持和维护动力以进行动态任务，从而为老年人中神经肌肉系统的疲劳提供了一种新的创新方法。最近的研究表明，在这些功能相关的任务中，老年人比年轻人经历更大的肌肉疲劳。但是，在肢体次次动态和姿势性收缩期间，老年人与年龄相关的肌肉疲劳增加的原因尚不清楚。根据初步数据，我们假设神经机制是老年人表现出的更大疲劳，而与年轻人相比，对次端疲劳收缩的收缩需要支撑惯性负荷。首先，我们研究了涉及支撑惯性负荷的动态和姿势任务肌肉疲劳与年龄相关的变化的机制。具体而言，我们将比较年轻人和老年人之间的任务失败时间进行姿势等距和动态任务，并在老年人中建立与年龄相关的疲劳与功能能力之间的关联（AIM 1）。我们还将确定在年轻人和老年人中为这些任务的任务失败有助于时间的神经机制（AIM 2）。为了完成AIM 2，我们将使用经颅磁刺激在疲劳之前，之中和之后检查皮质脊髓兴奋性，这将被量化为诱发电势的大小，应标准化为神经肌肉传播的变化（M波）。通过了解在功能相关的任务中导致与年龄相关的疲劳的大小和机制，我们可以确定适当且简单的康复技术，以改善老年人经历的疲劳。我们的初步数据表明，疲劳任务的“实践”将通过神经适应来提高性能。因此，我们将通过实践年轻人和老年人执行的姿势等距和动态任务来确定任务失败和皮质脊髓兴奋性的变化（AIM 3）。最后一个目标将评估“实践”作为一种康复技术的功效，改善神经肌肉功能缺陷并最大程度地减少老年人的损害，并提供与年龄相关的性能障碍的证据。