Biomechanical Effects of Industrial Eccentric Exertions

产品说明：本研究旨在探讨工业动力手工具操作中重复性离心负荷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。据推测，增加动力工具的反作用力和建立时间对应于更大的变化，在动力特性的上肢。基于实验室的实验将定义重复偏心用力（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旋后对抗电机，以模拟代表手枪式握把动力手动工具操作的偏心用力水平。峰值扭矩水平和建立时间将通过实验进行控制。前臂的机械性能将在一段时间的工作之前和之后进行测量。将使用独特的装置来确定机械参数，该装置将前臂建模为单自由度动态机械系统，当受试者使用最大努力来对抗其运动时，通过测量对自由振荡中的已知机械系统的干扰的角位移来确定。我们的初步数据表明，显着的刚度和惯性质量的变化时，观察到在类似的强度水平偏心行使。血液肌酸激酶（CK）的生化指标和使用前臂MRI中T2变化的解剖学指标将与受试者随机亚组重复离心运动之前和之后的生物力学参数进行比较。将使用视觉模拟量表评估主观不适，还将测量前臂水肿和力量。第二个实验将评估类似的上肢生物力学性能的产业工人定期进行重复的偏心努力不同的强度，建立时间和重复率在选定的工业工作。受试者将从当地汽车装配线上的工具操作工作中招募。这项研究最终可以导致更好的人体工程学干预措施，通过定量的电动手工具设计指南和工作实践的基础上了解接触到特定水平的反作用力，建立时间和重复的破坏性影响，以及提供新的结果措施的流行病学研究。

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.