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（提升负荷，姿势）和性别如何影响提升过程中脊柱的负荷耐受性。脊柱屈曲耐受性描述了在不稳定和随后的组织损伤的阈值处的载荷耐受性。屈曲耐受性由脊柱稳定性的神经肌肉控制来控制。拟议的研究是R 01 AR 46111的延续，我们证明：1）活动肌肉的僵硬和反射对于维持脊柱稳定性都是必要的; 2）这些因素受躯干伸展力、姿势和性别的影响。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。特定目标1将测量在自主躯干伸展运动过程中，活动肌肉的反射力和刚度如何通过负荷、姿势和性别进行修改，以模拟手动材料处理/提升任务。这些数据将用于校准脊柱屈曲载荷的受试者特定生物力学分析（固有肌肉刚度增益和反射增益的校准参数）。SPECIFIC AIM 2将在单独的动态提升用力中测量躯干动力学、运动学和EMG，以模拟低风险和高风险手动材料搬运/提升任务。将使用校准的受试者特定稳定性生物力学分析对这些数据进行分析，以输出脊柱屈曲公差作为提升载荷、姿势和性别的函数。具体目标3将比较经验测量的躯干稳定性与具体目标2中计算的数据。非线性动力学分析（Floquet乘数）将根据躯干伸展用力期间施加的小躯干扰动期间记录的数据确定，类似于特定目标2中记录的条件。将分别研究内在肌肉刚度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与提升相关的肌肉骨骼损伤的潜在病理生理学，可供人体工程学专家用于研究改进的MMH任务设计和工作场所更安全的性别包容性。

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.