Impact of control mechanisms and tissue morphology on upper extremity loading

与工作有关的疾病每年使加拿大人损失数十亿美元。非常需要充分了解上肢（肩、臂和手）组织在工作中变得超负荷的机制。 这些机制之所以有趣和复杂，是因为它们是在很长一段时间内发展起来的，因此很难确定造成损害的原因。 这些疾病涉及肌肉、结缔组织（例如网球肘、肌腱炎）和周围神经（例如腕管综合征）。 在了解这些疾病并使工人的工作更安全之前，必须表征健康组织如何对一系列负荷条件做出反应的机制。 我的研究计划，评估健康组织对各种姿势的反应，负载，干扰任务，疲劳（局部和中央），以及衰老。我们还必须了解解剖学和运动控制之间的复杂相互作用。 研究表明，负荷、姿势和运动与组织过载密切相关，这可能导致组织损伤。 然而，大多数研究是相关的，并没有解决为什么以及如何这些组织超载。 我们有一个基本的需要，了解组织如何反应的过多的条件，在工作和其他方面。 如果没有这些知识，我们可能会导致身体过度紧张的不良影响。 我的研究计划有条不紊地调查肌肉负荷的影响，通过监测手臂运动，肌肉活动及其相互作用，使用基于计算机的建模。 我们使用磁共振成像（MRI）和超声波来检查捏动作过程中不同姿势手腕组织的结构变化。 这些研究确定了腕部神经压迫的机制。我们还研究了肩部、手臂和手部的肌肉激活模式（时间和幅度），以确定肌肉如何在特定任务中产生运动。增加任务的复杂性可以改变某人执行任务的方式。 特别是，增加一个与主要任务竞争的任务，如抓握或精神负荷任务，可能会对结果有害。 控制手部、手臂和肩部肌肉的补偿策略可能表明哪些个体容易受到更大的个体肌肉负荷、疲劳和损伤的影响。 此外，通过对新鲜肌肉和疲劳肌肉的比较研究，我们可以确定人们如何处理像在装配线上一样令人疲惫的刻板动作。这项研究计划的一个主要部分是开发和改进我们的计算机模型，以预测手臂和手部的力量。通过在计算机模型中结合肌肉活动和解剖信息，我们可以测试有关疾病如何发展以及如何预防它们的理论，并询问“如果......会发生什么？“这些问题在其他情况下无法在生物伦理上得到回答。

Work-related disorders cost Canadians billions of dollars every year. There is a great need to fully understand the mechanisms by which tissues of the upper extremity (shoulder, arm, and hand) become overloaded at work. What makes these mechanisms interesting and complex is that they develop over a long period of time, making it difficult to pinpoint what caused the damage. These disorders involve muscle, connective tissue (e.g. tennis elbow, tendinitis), and peripheral nerves (e.g. carpal tunnel syndrome). Before understanding these disorders and making jobs safer for workers, it is essential to characterize the mechanisms underlying how healthy tissues respond to a range of loading conditions. My research program that evaluates the response of healthy tissues to a variety of postures, loads, interfering tasks, and fatigue (localized and central), as well as aging. We must also understand the complex interactions between anatomy and the control of movement. Studies indicate that loads, postures and motion are highly linked to overloading tissues which may lead to tissue damage. However, the majority of studies are correlative and do not address why and how these tissues are overloaded. We have a fundamental need to understand how tissues react to the plethora of conditions, at work and otherwise. Without this knowledge, we may cause the unwanted effect of over stressing the body. My research program methodically investigates the effects of muscular loading by monitoring arm movement, muscle activity and their interactions using computer-based modeling. We use magnetic resonance imaging (MRI) and ultrasound to examine structural changes in the tissues of the wrist in different postures during pinching actions. These studies determine mechanics of nerve compression at the wrist. We also examine muscle activation patterns (timing and magnitude) of the shoulder, arm and hand to determine how muscles work to create movement in specific tasks. Adding complexity to tasks can alter how someone performs the task. In particular, adding a task that competes with the main task, such as a grip or a mentally taxing task, may be detrimental to the outcome. Compensatory strategies to control the hand, arm and shoulder muscles may indicate which individuals are susceptible to greater individual muscle loading, fatigue and injury. Further, by performing studies comparing muscles fresh versus fatigued, we can determine the way people deal with tiring stereotypical movements like on an assembly line. A major part of this research program is to develop and improve our computer models to predict forces inside the arm and hand. By combining muscle activity and anatomical information in a computer model, we can test theories on how disorders develop and how to prevent them as well as ask "what would happen if ...?" questions that otherwise could not be answered ethically in living beings.