Motor Unit Activity and Force Steadiness Changes w Aging

运动单位活动和力稳定性随衰老的变化

• 批准号: 7107110
• 负责人: LISA GRIFFIN
• 金额: $ 6.96万
• 依托单位: UNIVERSITY OF TEXAS AT AUSTIN
• 依托单位国家: 美国
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-09-01 至 2008-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7107110
• 关键词: age difference; aging; behavioral /social science research tag; clinical research; data collection methodology /evaluation; denervation; electrodes; electrophysiology; fingers; functional ability; hand; human subject; motor neurons; neural degeneration; neuromuscular function; neurophysiology; questionnaires; sensorimotor system; single cell analysis

DESCRIPTION (provided by applicant): The neuromuscular system undergoes significant denervation and muscle atrophy during aging. Muscle force production becomes less steady, particularly during the controlled release of muscle force and during low-force contractions. The loss of control of hand dexterity is extremely detrimental to the quality of life in many older individuals and to those affected by disuse atrophy from musculoskeletal disease. This study will investigate possible mechanisms behind the decrease in hand steadiness during aging. We hypothesize that there is a higher incidence of self sustained firing in motoneurons of older adults and that this behavior contributes to the increased difficultly to release muscle force smoothly. Secondly, we hypothesize that there is an increase in motor unit synchronization and coherence across the muscles of the thumb and index finger in older adults and that this could account for the decrease in steadiness observed during functional hand tasks such as pinching. Finally, we will determine if changes in motor unit firing rate synchronization and coherence across the thumb and index finger are related to increases in force steadiness following resistance training in older adults. This study will encompass two sets of experiments performed before and after one-month training programs. The first will investigate single motor unit firing rates and the incidence of self sustained firing of muscles serving the thumb and index finger during independent thumb and finger contractions in younger and older adults. In a second set of experiments, all subjects will perform a pinching force-accuracy task and the degree of synchronization and coherence between the thumb and index finger in younger and older adults will be compared with cross correlation analysis. Twenty older adults will be divided into two groups which will undergo different training programs for four weeks. One group will perform a take-home resistance training program and a matched group will perform a precision motor learning program. The incidence of self-sustained firing in single motor units and motor unit firing rate synchronization and coherence during pinching will be measured again post training. This elucidation of the neuromuscular mechanisms that enable hand steadiness will provide the foundation for the design of advanced rehabilitation systems.

描述（由申请人提供）： 神经肌肉系统在衰老过程中经历显着的去神经支配和肌肉萎缩。肌肉力量的产生变得不太稳定，特别是在肌肉力量的受控释放期间和低力量收缩期间。手部灵活性的丧失对许多老年人和因肌肉骨骼疾病引起废用性萎缩的人的生活质量极为不利。这项研究将调查衰老过程中手部稳定性下降的可能机制。 我们假设老年人运动神经元自我持续放电的发生率较高，并且这种行为导致平滑释放肌肉力量的难度增加。其次，我们假设老年人拇指和食指肌肉的运动单位同步性和连贯性有所增加，这可能是在捏捏等功能性手部任务期间观察到的稳定性下降的原因。最后，我们将确定拇指和食指运动单位放电频率同步性和一致性的变化是否与老年人阻力训练后力量稳定性的增加有关。 这项研究将包括在一个月的培训计划之前和之后进行的两组实验。第一个研究将研究年轻人和老年人在独立拇指和手指收缩期间单个运动单位的放电率以及服务于拇指和食指的肌肉的自我持续放电的发生率。在第二组实验中，所有受试者都将执行捏力准确度任务，并将年轻人和老年人的拇指和食指之间的同步性和连贯性程度与互相关分析进行比较。二十名老年人将被分成两组，接受为期四个星期的不同训练计划。一组将执行带回家的阻力训练计划，另一组将执行精确运动学习计划。训练后将再次测量单个运动单位自持放电的发生率以及捏捏期间运动单位放电频率的同步性和连贯性。对实现手部稳定性的神经肌肉机制的阐明将为高级康复系统的设计提供基础。