Workplace Factors & Gender in Dynamic Spinal Stability

描述(由申请者提供)：本项目的目标是确定工作场所因素(举重、姿势)和性别在举重运动中如何影响脊柱的负荷耐力。脊柱屈曲耐受性描述了在失稳和随后的组织损伤门槛处的载荷耐受性。屈曲耐受性由神经肌肉控制的脊柱稳定性控制。这项拟议的研究是R01 AR46111的延续，我们证明：1)活动肌肉的僵硬和反射都是维持脊柱稳定所必需的；2)这些因素受到躯干伸展力量、姿势和性别的影响。这表明，性别和工作场所因素影响伤害容忍度(稳定性和相关的屈曲容忍度)。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。具体目标1将测量在自愿躯干伸展运动中，主动肌肉的反射力和僵硬如何随着负荷、姿势和性别的变化而改变，以模拟手动材料搬运/提举任务。这些数据将被用来校准特定于受试者的脊柱屈曲负荷的生物力学分析(校准的固有肌肉僵硬增益和反射增益参数)。特定的AIM 2将在单独的动态提升作业中测量躯干动力学、运动学和肌电，以模拟低风险和高风险的手动材料搬运/提升任务。这些数据将使用校准的、特定于受试者的生物力学稳定性分析来输出脊柱的屈曲耐受性，作为提升载荷、姿势和性别的函数。特定目标3将比较经验测量的躯干稳定性与特定目标2中计算的数据。非线性动力学分析(Floquet乘数)将从躯干伸展运动中应用与特定目标2中记录的条件类似的躯干小干扰时记录的数据中确定。内在肌肉僵硬和反射对脊柱稳定性的作用将单独进行研究。我们将考察负重、姿势和性别的影响。这项研究旨在深入了解与举重相关的肌肉骨骼损伤的潜在病理生理学，人体工程学专家可以使用这些病理生理学来研究改进的MMH任务设计和工作场所更安全的性别包容。

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.