Tracking Fatigue-Related Changes in Motor Coordination

描述（由申请人提供）：重复性劳损（RSI）影响成千上万的人，每年给美国经济造成超过140亿美元的损失。长期以来，人们一直认为，在重复性任务中不正确的姿势或动作会增加患RSI的风险。肌肉疲劳可能是这一过程中一个重要的中介因素，因为肌肉疲劳会导致协调性的改变，从而产生不正确的运动，随着时间的推移，这可能反过来增加RSI的风险。本R21应用程序的目的是开发和测试新方法的能力，以跟踪疲劳重复运动期间肌肉功能和协调发生的变化。将构建一个设备来模拟上肢重复性任务，已知会引起疲劳后协调性的变化。通过扩展现有的用于跟踪机械系统损伤积累的非线性动力学算法，也将开发用于跟踪观察到的协调变化的疲劳的适当分析工具。因为这种方法可以跟踪适当重构状态空间中的扭曲，它可以提供有效的潜在（隐藏）损伤动力学测量，而不需要详细的基于物理的系统或损伤动力学数学模型。目前可用的算法将被修改，以解释机械系统和生物系统之间最突出的差异：噪声，多时间尺度动力学和非单调损伤动力学（即生物适应性）。最后，这些和更传统的措施将被应用于探索在重复性工作任务中发生的肌肉功能和运动协调变化的时间过程。30名健康受试者将在三种条件下完成任务，直到自愿精疲力竭：在较高的工作高度下，更多的限制，较少的限制和较少的限制。假设：(1)局部肌肉疲劳的变化会先于肌肉协调性的变化，而肌肉协调性的变化又会先于明显的运动学变化；(2)这一系列事件在限制较少的情况下会延迟；(3)这些变化在工作高度升高的情况下会发生得更快；(4)非线性跟踪方法会揭示协调性的细微变化，这些变化反映了肌肉疲劳状态的潜在（隐藏）变化。该项目将对重复性任务中发生的生物力学和神经适应的性质和时间过程产生新的见解，并将为开发改进的诊断技术提供必要的基础，以在未来的工作中识别早发性（临床前）RSI。希望有一天，这些努力将有助于减少与这些伤害相关的巨大的个人和金钱成本。

DESCRIPTION (provided by applicant): Repetitive strain injuries (RSI) affect thousands of people and cost the US economy more than $14 billion each year. It has long been believed that improper postures or movements made during repetitive tasks increase the risks of developing RSI. Muscle fatigue may be an important intermediary factor in this process, since muscle fatigue can induce changes in coordination that generate improper movements, which may in turn increase the risk of RSI over time. The purpose of this R21 application is to develop and test the ability of new methods to track the changes that occur in both muscle function and coordination during fatiguing repetitive movements. A device will be constructed to simulate an upper extremity repetitive task known to induce changes in coordination after fatigue. Appropriate analytical tools for tracking fatigue from observed changes in coordination will also be developed by extending existing nonlinear dynamics algorithms developed for tracking damage accumulation in mechanical systems, Because this approach tracks distortions in appropriately reconstructed state spaces, it can provide valid measures of the underlying (hidden) damage dynamics without the need for detailed physics-based mathematical models of either the system or damage dynamics. Currently available algorithms will be modified to account for the most prominent differences between mechanical and biological systems: noise, multiple time scale dynamics, and non-monotonic damage dynamics (i.e. biological adaptability). Finally, these and more traditional measures will be applied to explore the time courses of changes in muscle function and motor coordination that occur during the repetitive work task. 30 healthy subjects will perform the task until voluntary exhaustion under three conditions: more restricted, less restricted, and less restricted at elevated work height. It is hypothesized that (1) changes in local muscle fatigue will precede changes in muscle coordination, which will in turn precede overt changes in kinematics, (2) this sequence of events will be delayed in the less restricted condition, (3) these changes will occur more rapidly in the elevated work height condition, and (4) the nonlinear tracking approaches will reveal subtle changes in coordination that reflect underlying (hidden) changes in muscle fatigue state. This project will generate new insights into the nature and time course of the biomechanical and neural adaptations that occur during repetitive tasks and will provide the necessary foundation for developing improved diagnostic techniques to identify early-onset (pre-clinical) RSI in future work. It is hoped that these efforts will one day help reduce the tremendous personal and monetary costs associated with these injuries.