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更相关的任务中与年龄相关的神经肌肉疲劳的原因，这些任务对于美国老龄化人口中老年人保持独立性很重要。该提案提出了一种新的创新方法，通过检查功能相关的任务来了解老年人神经肌肉系统的疲劳性，这些任务需要在有限的肢体支撑下控制负载并维持动态任务的功率。最近的研究表明，在这些与功能相关的任务中，老年人比年轻人经历更严重的肌肉疲劳。然而，老年人在肢体支撑有限的次最大动态和姿势收缩期间，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，我们假设神经机制导致老年人比年轻人表现出更大的疲劳，因为需要支撑惯性负载的次最大疲劳收缩。首先，我们研究了涉及支撑惯性负载的动态和姿势任务的肌肉疲劳与年龄相关的变化的机制。具体来说，我们将比较年轻人和老年人在姿势等长和动态任务中任务失败的时间，并建立老年人与年龄相关的疲劳和功能能力之间的关联（目标 1）。我们还将确定导致年轻人和老年人执行这些任务失败的时间的神经机制（目标 2）。为了实现目标 2，我们将使用经颅磁刺激来检查疲劳之前、期间和之后的皮质脊髓兴奋性，并将其量化为标准化为神经肌肉传播（M 波）变化的运动诱发电位的大小。通过了解在功能相关任务中导致与年龄相关的疲劳的程度和机制，我们可以确定适当且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，“练习”疲劳任务将通过神经适应来提高表现。因此，我们将通过年轻人和老年人执行姿势等长和动态任务的练习来确定任务失败和皮质脊髓兴奋性的时间变化（目标 3）。最后一个目标将评估“练习”作为一种康复技术的功效，以改善神经肌肉功能缺陷并最大程度地减少老年人的损伤，并提供与年龄相关的神经功能损伤的证据。