Tracking Fatigue-Related Changes in Motor Coordination

描述(申请人提供)：重复性劳损(RSI)影响数以万计的人，每年给工人和美国经济造成超过70亿美元的损失。人们认为，在重复性任务中做出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，这反过来可能会增加RSI的风险。此R21应用程序的目的是开发新的方法来跟踪疲劳重复运动过程中肌肉功能和协调性的变化，并测试这些方法的可行性。首先，我们将构建一个装置来模拟一项已知的在疲劳后导致协调性变化的任务(锯切)。我们将建立适当的任务参数，以在30到45分钟内诱发疲劳。其次，我们将开发一套适当的分析工具，用于根据观察到的协调变化来跟踪疲劳。我们将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。由于我们的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，而不需要详细的基于物理的系统或损伤动力学的数学模型。然而，我们需要修改这些算法，以适应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，我们将应用这些方法，以及更传统的方法，来探索锯切任务中肌肉功能和运动协调性变化的时间进程。30名健康受试者在限制较多和限制较少两种情况下进行连续锯切直到自愿耗尽为止。我们将检验三个假设：(1)局部肌肉疲劳的变化先于肌肉协调性的变化，而肌肉协调性的变化反过来又先于运动学的显性变化，(2)在限制较少的条件下，这一事件序列将被延迟，以及(3)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中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，并将为我们开始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。我们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金钱和个人成本

DESCRIPTION (provided by applicant): Repetitive strain injuries (RSI) affect tens of thousands of people and cost workers and the US economy more than $7 Billion each year. It is 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, which may in turn increase the risks of RSI. The purpose of this R21 application is to develop new methods to track the changes that occur in both muscle function and coordination during fatiguing repetitive movements and to test the feasibility of these approaches. First, we will construct a device to simulate a task (sawing) known to induce changes in coordination after fatigue. We will establish appropriate task parameters to induce fatigue over 30 to 45 minutes. Second, we will develop an appropriate set of analytical tools for tracking fatigue from observed changes in coordination. We will extend existing nonlinear dynamics algorithms developed for tracking damage accumulation in mechanical systems. Because our 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. We will need to modify these algorithms, however, to accommodate the most prominent differences between mechanical and biological systems: noise, multiple time scale dynamics, and non-monotonic damage dynamics (i.e. biological adaptability). Finally, we will apply these methods, along with more traditional measures, to explore the time courses of changes in muscle function and motor coordination that occur during the sawing task. Thirty healthy subjects will perform the continuous sawing task until voluntary exhaustion under two conditions: more restricted and less restricted. We will test three hypotheses: (1) changes in local muscle fatigue precede changes in muscle coordination, which in turn precede overt changes in kinematics, (2) this sequence of events will be delayed in the less restricted condition, and (3) 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 from which we will begin to develop improved diagnostic techniques for identifying early-onset (pre-clinical) RSI. We hope these efforts will one day help reduce the tremendous monetary and personal costs associated with these injuries