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Changes in Control of Movement Timing and Stability With Muscle Fatigue

肌肉疲劳时运动时机和稳定性控制的变化

基本信息

批准号：
7667946
负责人：
Jonathan B Dingwell
金额：
$ 7.07万
依托单位：
UNIVERSITY OF TEXAS AT AUSTIN
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：
2008-09-01 至 2011-02-28
项目状态：
已结题

项目摘要

DESCRIPTION (provided by applicant): Work-related musculoskeletal injuries have been linked to movement repetition, improper postures, and muscle fatigue. Muscle fatigue and/or the muscle imbalances that result from fatigue may be important as direct causes and/or intermediary factors in injury development. To develop appropriate prescriptions for preventing injuries and effective strategies for rehabilitation, it is critical to understand how fatigue muscle and muscle imbalances affect the control of goal-directed movements. Thirty healthy young adults will perform an upper extremity low-load continuous work task similar to sawing for 5 minutes in time with a metronome. They will then perform either of two fatigue protocols to induce either widespread fatigue (more sawing with increased resistance) or localized muscle fatigue (repetitive shoulder flexion). They will then perform another 5 minutes of low-load sawing. Between each segment of the protocol, rates of perceived exertion and maximum voluntary contractions (MVCs) will be recorded. Kinematics, handle forces, and muscle activity (EMG) will be recorded continuously during all sawing trials. Proper movement timing is critical to many repetitive tasks. The PIs will apply novel methods to decompose the variability in the primary spatial-temporal task variables into new variables that directly affect achieving the task goal and those that do not. They will quantify both the variability and cycle-to-cycle temporal correlation structure of each resulting time series to determine how humans control movement timing during redundant goal-directed movements and how this control is altered with either widespread or localized muscle fatigue. Controlling movement stability during repetitive tasks is also critical for minimizing risk of injury. However, how muscle fatigue and/or muscle imbalances affect the control of movement stability is not well understood. The PIs will apply innovative analysis methods, developed by their lab, to directly quantify each subject's innate sensitivity to small perturbations during the continuous sawing task trials. These analyses will allow them to determine how both widespread vs. localized muscle fatigue affect the control of movement stability. This R03 project will yield vital new insights into how muscle fatigue affects task performance, about the neuromuscular and biomechanical strategies humans use to achieve this performance, and about the underlying control policies subjects adopt. Answering these fundamental questions is critical for understanding the mechanisms of musculoskeletal injury development and for developing effective rehabilitation strategies for treating patients with these injuries. Upper extremity musculoskeletal injuries (not including low back pain) are a significant and costly health care problem affecting over 375,000 people in the work-place each year. Muscle fatigue and muscle imbalances are significant contributors to these injuries. Therefore, it is important to better understand how muscle fatigue and muscle imbalances caused by localized muscle fatigue affect how humans control the timing and dynamic stability of repetitive movements.

描述(由申请人提供)：与工作相关的肌肉骨骼损伤与重复运动、不正确的姿势和肌肉疲劳有关。肌肉疲劳和/或由疲劳引起的肌肉失衡可能是损伤发展的直接原因和/或中介因素。为了开发预防损伤的适当处方和有效的康复策略，了解疲劳肌肉和肌肉失衡如何影响目标定向运动的控制至关重要。 30名健康的年轻成年人将用节拍器进行类似于锯5分钟的上肢低负荷连续工作任务。然后，他们将执行两种疲劳方案中的任何一种，以引起广泛性疲劳(更多的锯切，阻力增加)或局部肌肉疲劳(重复的肩部屈曲)。然后，他们将再进行5分钟的低负荷锯切。在协议的每个部分之间，将记录感觉到的劳累和最大自愿收缩(MVC)的比率。在所有锯切试验过程中，将连续记录运动学、操纵力和肌肉活动(EMG)。正确的运动时机对于许多重复的任务至关重要。绩效指标将应用新的方法，将主要时空任务变量中的可变性分解为直接影响任务目标实现和不直接影响任务目标实现的新变量。他们将量化每个产生的时间序列的可变性和周期到周期的时间相关性结构，以确定人类在冗余的目标定向运动中如何控制运动时机，以及这种控制是如何随着广泛的或局部的肌肉疲劳而改变的。在重复任务中控制运动稳定性对于将受伤风险降至最低也是至关重要的。然而，肌肉疲劳和/或肌肉失衡如何影响运动稳定性的控制还不是很清楚。PI将应用他们实验室开发的创新分析方法，直接量化每个受试者在连续锯切任务试验中对微小扰动的天生敏感性。这些分析将使他们能够确定广泛性肌肉疲劳和局限性肌肉疲劳如何影响运动稳定性的控制。这个R03项目将对肌肉疲劳如何影响任务表现，关于人类用来实现这一表现的神经肌肉和生物力学策略，以及关于受试者采用的基本控制策略，产生至关重要的新见解。回答这些基本问题对于了解肌肉骨骼损伤的发展机制以及制定有效的康复策略来治疗这些损伤患者至关重要。上肢肌肉骨骼损伤(不包括腰部疼痛)是一个重大且昂贵的保健问题，每年影响工作场所的375,000多人。肌肉疲劳和肌肉失衡是导致这些损伤的重要因素。因此，更好地了解局部肌肉疲劳引起的肌肉疲劳和肌肉失衡如何影响人类控制重复运动的时机和动态稳定性是很重要的。