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Steadiness in Older Adults

老年人的稳定性

基本信息

批准号：
7848041
负责人：
ROGER M. ENOKA
金额：
$ 1.12万
依托单位：
UNIVERSITY OF COLORADO
依托单位国家：
美国
项目类别：
财政年份：
2009
资助国家：
美国
起止时间：
2009-07-15 至 2010-10-31
项目状态：
已结题

项目摘要

DESCRIPTION (provided by applicant): Many older adults are less steady when exerting low forces and lifting light loads. The greater fluctuations in force exhibited by older adults can be caused either by increased discharge rate variability or by altered amounts of correlated activity among the motor units. Based on prior experimental and computational studies, we hypothesize that the greater fluctuations experienced by older adults during voluntary contractions are due to direct and indirect effects of correlated motor unit discharge. Aim 1 will extend our current model of the electromyogram (EMG) to simulate the reorganization of the neuromuscular system that occurs with advancing age. The simulations will assess the effect of cancellation of motor unit potentials on the amplitude of the surface EMG and will evaluate the validity of estimating common modulation of motor unit discharge from the EMG signal. Aim 2 will evaluate the fluctuations in force and acceleration during isometric and anisometric contractions performed with the first dorsal interosseus muscle by young and old adults. The time- and frequency-domain characteristics will be compared with prior experimental measurements and modeling results for young adults. Aim 3 will compare the contributions of the two candidate neural mechanisms (discharge rate variability and correlated discharge) to the differences between young and old adults in index finger acceleration when performing isometric and anisometric contractions with the first dorsal interosseus muscle. Aim 4 will examine the role of coactivation at the level of the motor unit by measuring the amount and timing of correlated discharge between motor units in the agonist and antagonist muscles. These studies will provide novel information on the neural mechanisms that contribute to the reduced ability of older adults to perform steady contractions.

描述(申请人提供)：许多老年人在施加低力和举起轻负荷时不太稳定。老年人表现出的更大的力量波动可能是由于放电率变异性增加或运动单位之间相关活动量的改变引起的。基于先前的实验和计算研究，我们假设老年人在自愿收缩期间经历的更大的波动是由于相关运动单位放电的直接和间接影响。目的1将扩展我们目前的肌电模型(EMG)，以模拟随着年龄的增长而发生的神经肌肉系统的重组。模拟将评估消除运动单位电位对表面肌电幅度的影响，并将评估从EMG信号估计运动单位放电的共同调制的有效性。目的2将评估年轻人和老年人对第一骨间背侧肌肉进行等长和等长收缩时的力和加速度的波动。时间域和频域特性将与先前针对年轻人的实验测量和建模结果进行比较。目的3比较两种候选神经机制(放电率变异性和相关放电率)对年轻人和老年人在进行第一骨间背肌等长和不等长收缩时食指加速度的差异的贡献。目的4将通过测量激动者和拮抗者肌肉中运动单位之间的相关放电的数量和时间，来检验在运动单位水平上的共同激活的作用。这些研究将为导致老年人进行稳定收缩能力下降的神经机制提供新的信息。