Tracking Fatigue-Related Changes in Motor Coordination

描述(申请人提供)：重复性劳损(RSI)影响数以千计的人，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，在重复性任务中做出的不正确的姿势或动作会增加发生RSI的风险。肌肉疲劳可能是这一过程中的一个重要中介因素，因为肌肉疲劳会导致协调性改变，从而产生不适当的运动，这反过来可能会随着时间的推移增加RSI的风险。此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性的变化。将建造一种装置来模拟上肢重复的任务，众所周知，这种任务会在疲劳后导致协调性的变化。还将通过扩展为跟踪机械系统中的损伤累积而开发的现有非线性动力学算法来开发适当的分析工具来跟踪从观察到的协调变化中的疲劳，因为这种方法跟踪适当重建的状态空间中的扭曲，它可以提供潜在(隐藏的)损伤动力学的有效测量，而不需要基于系统或损伤动力学的详细的基于物理的数学模型。目前可用的算法将进行修改，以考虑机械系统和生物系统之间最显著的差异：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，这些和更传统的方法将被用来探索重复工作任务中肌肉功能和运动协调性变化的时间进程。30名健康受试者将在三种情况下进行这项任务，直到自愿筋疲力尽：限制较多、限制较少和在高空工作时限制较少。假设(1)局部肌肉疲劳的变化将先于肌肉协调性的变化，而肌肉协调性的变化又将先于运动学的显性变化，(2)这一系列事件将在较少限制的条件下延迟，(3)这些变化在工作高度升高的条件下发生得更快，以及(4)非线性跟踪方法将揭示协调的细微变化，反映肌肉疲劳状态的潜在(隐藏)变化。该项目将对重复任务期间发生的生物力学和神经适应的性质和时间进程产生新的见解，并将为在未来的工作中开发改进的诊断技术以识别早发性(临床前)RSI提供必要的基础。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.