Aging, Neuromuscular Behavior, and Risk of Occupational Low Back Pain

描述(申请人提供)：腰背部疾病，特别是下腰痛(LBP)，仍然是最常见和衰弱的与工作有关的肌肉骨骼疾病。随着年龄的增长，LBP的患病率不断增加，随着老年人越来越多地参与工作，促使人们更好地理解衰老与LBP之间的潜在机制。脊柱在各种工作活动/事件下的异常力学(即更高的脊柱负荷和更低的稳定性)最终可能导致LBP。脊柱生物力学取决于任务/事件的物理需求(例如，外部负荷)、被动的躯干机械特性(例如，刚度和阻尼)以及对平衡和稳定性要求的主动机械神经肌肉反应。尽管目前对躯干组织与年龄相关的降解有了解，但躯干机械行为(TMB--包括主动和被动)的总体结果尚不清楚。在各种工作活动/事件下，TMB随年龄的变化如何影响脊柱生物力学也是未知的。基于当代因果生物力学理论和我们的先导数据，形成了两个假说，并将在目前的应用中进行研究。特别是，通过因果生物力学理论将衰老与LBP联系起来，表明：1)TMB存在与年龄相关的变化；2)这些变化对脊柱生物力学产生不利影响。对脊柱生物力学的不利影响是在特定任务/事件(例如，举重/坡度)下脊柱负荷增加和脊柱稳定性降低。TMB的变化可能会对脊柱生物力学产生不利影响，包括躯干僵硬、减震、反射潜伏期延长和反射反应减弱。本应用的目的是通过解决两个具体目标来探索衰老和脊柱生物力学之间的关系：目标1：TMB如何随年龄变化？目的2：TMB的这种与年龄相关的变化是否会对脊柱生物力学产生不利影响？TMB和脊柱生物力学将使用一套新的体内实验方法进行评估，包括被动躯干测试(即应力松弛)和突然加载实验，结合有限元建模和一系列系统识别技术。这里的重点是将危险因素(即年龄)与异常的脊柱力学联系起来的生物力学理论方面，特别是通过危险因素对TMB和脊柱力学的影响，这些方面尚未被探索。一套新的强大的工具可用于全面评估TMB和脊柱生物力学，这将使我们能够第一次探索因果生物力学理论的这些方面。更好地了解潜在的致病机制不仅有助于预防，而且对于职业性下腰痛患者的有效康复和安全重返工作也至关重要。通过量化TMB中与年龄相关的改变及其对脊柱生物力学的影响，我们期望建立一个基础，在此基础上开发和实施适合年龄的LBP控制措施。 公共卫生相关性：在这项应用中，将探索与年龄相关的人体躯干机械行为变化的潜在作用，以及通过其对脊柱生物力学的不利影响而在下腰痛发展中的潜在作用。与NIOSH的研究目标一致，该项目寻求调查和确定风险因素(这里是老龄化)与相关职业病和伤害之间的关系。它还涉及减少腰痛的发生率和严重程度的战略目标，这一点存在于最近的国家职业研究议程中的大多数部门，并特别强调老年工人。

DESCRIPTION (provided by applicant): Low back disorders, and low back pain (LBP) in particular, remain as the most common and debilitating work-related musculoskeletal disorder. An increasing LBP prevalence with aging, along with an increasing participation of older individuals at work, motivates a better understanding of underlying mechanisms linking aging with LBP. Abnormal mechanics of the spinal column (i.e., higher spinal loads and lower stability) under various work activities/events can eventually result in LBP. Spine biomechanics depend on the physical demands of a task/event (e.g., external loading), passive trunk mechanical characteristics (e.g., stiffness, and damping), and active mechanical neuromuscular response to equilibrium and stability requirements. Despite current knowledge on the age-related degradation of trunk tissues, the overall resultant changes in trunk mechanical behaviors (TMB - both active and passive) are unknown. It is also unknown how changes in TMB with age can influence spine biomechanics under various work activities/events. On the basis of contemporary causal biomechanical theory and our pilot data, two hypotheses were shaped and will be investigated in the present application. Particularly, linking aging with LBP via causal biomechanical theory suggests that: 1) there are age-related changes in TMB and 2) that these changes adversely affect spine biomechanics. Adverse effects on spine biomechanics are increases in spinal loads and decreases in spine stability for a given task/event (e.g., lifting/slp). Changes in TMB that could adversely affect spine biomechanics may include stiffer trunk, reduced damping, increased reflex latency, and decreased reflex response. The aim of present application is to explore such relationships between aging and spine biomechanics by addressing two specific aims: Aim 1: How does TMB change with age? Aim 2: Do such age-related changes in TMB adversely affect spine biomechanics? TMB and spine biomechanics will be evaluated using a novel set of in vivo experimental methods, including passive torso tests (i.e., stress-relaxation) and sudden loading experiments, coupled with finite element modeling and a series of system identification techniques. The emphasis here is on aspects of the biomechanical theory that link a risk factor (i.e., aging) to abnormal spine mechanics, specifically via the influences of the risk factor on TMB and spine mechanics, and which have not yet been explored. Availability of a new set of powerful tools to comprehensively assess TMB and spine biomechanics will enable us to explore these facets of the causal biomechanical theory for the first time. A better understanding of potential causal mechanisms not only contributes to prevention, but also is critical for efficient rehabilitation and safe return-to-wor of workers with occupational LBP. By quantifying age-related alterations in TMB and the resultant effects on spine biomechanics, we expect to establish a foundation from which to develop and implement age-appropriate controls for LBP. PUBLIC HEALTH RELEVANCE: The potential role of age-related changes in mechanical behaviors of the human trunk, and in the development of low back pain via their adverse effects on spine biomechanics, will be explored in this application. Consistent with the research objectives of NIOSH, the project seeks to investigate and identify the relationships between a risk factor, here aging, and associated occupational diseases and injuries. It also addresses the strategic goal to reduce the incidence and severity of low back pain, which is present within most sectors in the recent National Occupational Research Agenda, and with particular emphasis on older workers.