Biomechanical Effects of Industrial Eccentric Exertions

描述：本研究通过研究工业动力手工具操作中重复偏心用力对肌肉和肌腱生物力学特性的影响，以更好地了解与工作相关的肌肉骨骼疾病的病因和预防。假设电动工具反作用力和建立时间的增加与上肢动力特性的更大变化相对应。基于实验室的实验将确定重复的偏心用力(即反作用力大小和建立时间)和上肢特性(即刚度、粘性阻尼和惯性质量)之间的短期关系。受试者将反复抵抗前臂向后靠在马达上，以模拟手枪握力、力量、手工具操作的偏心用力水平。峰值扭矩水平和建立时间将由实验控制。前臂机械性能将在工作前和一段时间后进行测量。机械参数将使用一种独特的仪器来确定，该仪器将前臂建模为单自由度动态机械系统，方法是测量当受试者尽最大努力反对其运动时，扰动对已知机械系统的角位移。我们的初步数据显示，当以类似的强度水平进行偏心运动时，观察到显著的刚度和惯性质量变化。血液肌酸激酶(CK)的生化测量，以及利用前臂MRI T2变化进行的解剖测量，将与随机亚组受试者重复离心运动前后的生物力学参数进行比较。主观不适感将使用视觉模拟标尺进行评估，前臂浮肿和力量也将被测量。第二个实验将评估产业工人的类似上肢生物力学特性，这些工人在选定的工业工作中定期进行不同强度、准备时间和重复率的重复偏心运动。受试者将从当地一条汽车装配线上的工具操作工作中招募。这项研究最终可以通过量化的电动手工具设计指南和工作实践，在了解暴露于特定水平的反应力、累积时间和重复的破坏性影响的基础上，最终产生更好的人体工学干预措施，并为流行病学研究提供新的结果衡量标准。

DESCRIPTION: This research studies the effects of repetitive eccentric exertions in industrial power hand tool operation on biomechanical properties of muscle and tendon in order to better understand the etiology and prevention of work related musculoskeletal disorders. It is hypothesized that increased power tool reaction force and build-up time corresponds with greater changes in the dymanic characteristics of the upper limb. A laboratory-based experiment will define the short-term relationship between repetitive eccentric exertions (i.e. reaction force magnitude and build-up time) and upper limb properties (i.e. stiffness, viscous damping and inertial mass). Subjects will repetitively resist forearm supination against a motor for simulating eccentric exertion levels representative of pistol grip power hand tool operation. Peak torque levels and build-up time will be experimentally controlled. Forearm mechanical properties will be measured before and following a period of work. Mechanical parameters will be ascertained using a unique apparatus that models the forearm as a single degree-of-freedom dynamic mechanical system by measuring the angular displacement of a disturbance to a known mechanical system in free oscillation when the subject uses maximal effort to oppose its motion. Our preliminary data reveals that significant stiffness and inertial mass changes are observed when exercising eccentrically at similar intensity levels. Biochemical measures of blood creatine kinase (CK), and anatomical measures using T2 changes in an MRI of the forearms will be compared with biomechanical parameters prior to, and following repetitive eccentric exertions for a random subset of the subjects. Subjective discomfort will be assessed using a visual analog scale, and forearm edema and strength will also be measured. The second experiment will assess similar upper limb biomechanical properties for industrial workers who regularly perform repetitive eccentric exertions of varying intensity, build-up time and repetition rate in selected industrial jobs. Subjects will be recruited from tool operation jobs on a local automobile assembly line. This research can ultimately lead to better ergonomic interventions through quantitative power hand tool design guidelines and work practices based on understanding the damaging effects of exposure to specific levels of reaction force, build-up time and repetition, as well as providing new outcome measures for epidemiological studies.