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

描述（由申请人提供）：下背部疾病，特别是下背部疼痛（LBP），仍然是最常见和使人衰弱的与工作相关的肌肉骨骼疾病。随着年龄的增长，LBP患病率的增加，以及老年人参与工作的增加，促使人们更好地了解衰老与LBP之间的潜在机制。在各种工作活动/事件下脊柱的异常力学（即脊柱负荷增加和稳定性降低）可最终导致下腰痛。脊柱生物力学取决于任务/事件的物理需求（例如，外部负载），被动躯干力学特征（例如，刚度和阻尼）以及主动机械神经肌肉对平衡和稳定性要求的反应。尽管目前对树干组织的年龄相关退化有所了解，但树干机械行为（主动和被动）的总体变化尚不清楚。TMB随年龄的变化如何影响各种工作活动/事件下的脊柱生物力学也是未知的。在当代因果生物力学理论和我们的试点数据的基础上，形成了两个假设，并将在目前的应用中进行调查。特别是，通过因果生物力学理论将衰老与腰痛联系起来表明：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脊柱负荷的增加和给定任务/事件（例如，举/slp）脊柱稳定性的降低。TMB的变化可能对脊柱生物力学产生不利影响，包括躯干变硬、阻尼减少、反射潜伏期增加和反射反应减少。本应用的目的是通过解决两个特定的目的来探索衰老和脊柱生物力学之间的关系：目的1:TMB如何随年龄变化？目的2：年龄相关的TMB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颖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，再加上有限元建模和一系列系统识别技术。这里的重点是生物力学理论的各个方面，这些方面将危险因素（即衰老）与脊柱力学异常联系起来，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。一套全面评估TMB和脊柱生物力学的新强大工具的可用性将使我们能够首次探索因果生物力学理论的这些方面。更好地了解潜在的因果机制不仅有助于预防，而且对于职业性腰痛患者的有效康复和安全重返工作岗位至关重要。通过量化年龄相关的TMB变化及其对脊柱生物力学的影响，我们希望为制定和实施适合年龄的腰痛控制奠定基础。

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.