Workplace Factors & Gender in Dynamic Spinal Stability

描述（由申请人提供）：本项目的目标是确定工作场所因素（举起的负荷、姿势）和性别如何影响脊柱在举起时的负荷承受能力。脊柱屈曲耐受性描述了在不稳定和随后的组织损伤阈值处的负荷耐受性。屈曲耐受性是由脊柱稳定性的神经肌肉控制来控制的。拟议的研究是R01 AR46111的延续，我们证明了：1)活动肌肉和反射的刚度对于维持脊柱稳定性都是必要的；2)躯干伸展力、体位和性别对这些因素的影响。这表明性别和工作场所因素影响损伤耐受性（稳定性和相关的屈曲耐受性）。为了了解工作场所因素如何影响脊柱稳定性和屈曲载荷，我们将完成三个具体目标。SPECIFIC AIM 1将测量在自主躯干伸展运动中，活动肌肉的反射力和僵硬度如何因负荷、姿势和性别而改变，以模拟手动搬运/举起材料的任务。这些数据将用于校准脊柱屈曲载荷的受试者特异性生物力学分析（校准固有肌肉刚度增益和反射增益的参数）。SPECIFIC AIM 2将在单独的动态提升动作中测量躯干动力学、运动学和肌电图，以模拟低风险和高风险的手动材料处理/提升任务。这些数据将使用校准的、受试者特定的稳定性生物力学分析来分析，以输出脊柱屈曲容忍度作为举起的载荷、姿势和性别的函数。特异性AIM 3将比较经验测量的躯干稳定性与特异性AIM 2中计算的数据。非线性动态分析（Floquet乘数）将根据在躯干伸展时施加的小躯干干扰期间记录的数据确定，类似于具体目标2中记录的条件。我们将分别研究内在肌肉僵硬和反射对脊柱稳定性的作用。将检查负荷、姿势和性别的影响。本研究旨在深入了解举重相关肌肉骨骼损伤的潜在病理生理学，可用于人体工程学专家研究改进的MMH任务设计和更安全的工作场所性别融合。

DESCRIPTION (provided by applicant): The goal of this project is to identify how workplace factors (lifted load, posture) and gender influence the loading tolerance of the spine during lifting exertions. Spinal buckling tolerance describes the loading tolerance at the threshold of instability and subsequent tissue injury. Buckling tolerance is controlled by neuromuscular control of spinal stability. The proposed research is a continuation of R01 AR46111 where we demonstrated: 1) stiffness of active muscles and reflexes are both necessary to maintain spinal stability; and 2) these factors are influenced by trunk extension force, posture, and gender. These indicate that gender and workplace factors influence injury tolerance (stability and associated buckling tolerance). To understand how workplace factors influence spinal stability and buckling load we will complete three specific aims. SPECIFIC AIM 1 will measure how reflex force and stiffness of active muscles are modified by load, posture and gender during voluntary trunk extension exertions to simulate manual materials handling / lifting tasks. These data will be used to calibrate a subject-specific biomechanical analysis of spinal buckling load (calibrated parameters of intrinsic muscle stiffness gain and reflex gain). SPECIFIC AIM 2 will measure the torso kinetics, kinematics and EMG in separate dynamic lifting exertions to simulate low- risk and high-risk manual materials handling / lifting tasks. These data will be analyzed using the calibrated, subject-specific biomechanical analysis of stability to output buckling tolerance of the spine as a function of lifted load, posture and gender. SPECIFIC AIM 3 will compare empirically measured torso stability with the data computed in specific Aim 2. Nonlinear dynamic analyses (Floquet multipliers) will be determined from data recorded during small torso disturbances applied during trunk extension exertions similar to conditions recorded in Specific Aim 2. The roles of intrinsic muscle stiffness and reflex contributes to spinal stability will be investigated separately. Effects of load, posture and gender will be examined. This research is designed to provide insight into the underlying pathophysiology of lifting-related musculoskeletal injury that can be used by ergonomic experts to investigate improved MMH task design and safer gender inclusion in the workplace.