ABSTRACT Low back pain (LBP) is a major cause of disability in older adults, leading to reduced functional independence, work capacity, and life expectancy. Exposure to repetitive lifting and lowering tasks is a risk for low back injury. Given that the number individuals aged 65 years and older in the workforce will grow by 60% from 8.3 to 13.4 million between 2014 and 2024, it is essential to develop effective interventions to reduce the incidence of back injury in older adults during workplace lifting/lowering tasks. Recently, wearable passive back-support exoskeletons (BSEs) have been proposed as a promising, cost-effective intervention to reduce the risk of back injuries by offloading the weight of the wearer's torso. Although we and others have reported the potential efficacy of passive BSEs in younger adults during lifting, assembly and static holding tasks, no studies have examined the efficacy and suitability of passive BSEs in older adults, who are generally weaker and may have more mobility limitations. Furthermore, no studies have reported whether BSEs reduce spinal loading during lifting tasks, an important concern given the potential for vertebral fracture in older adults with osteoporosis. Thus, to address these knowledge gaps, the overall objective of this proposal is to conduct a comprehensive biomechanical evaluation of a novel passive BSE to quantify its utility for back injury prevention in older adults during simulated workplace tasks and other routine activities. In Aim 1 we will determine the impact of the BSE on muscle activity (using electromyography), kinematics (using 3D motion analysis), and subject-reported outcomes (i.e., perceived exertion, balance, comfort, and usability) during lifting and static holding tasks in 12 older adults. In Aim 2, we will employ a novel multibody musculoskeletal model of the thoracolumbar spine developed in our laboratory to calculating trunk muscle forces as well as spinal loading. We will create and validate new versions of these subject-specific musculoskeletal models that incorporate the BSE to predict trunk muscle forces and compressive spinal loading for all tasks in Aim 1. These models will be generated using the kinematic data, spine curvature, and muscle morphology measurements obtained via CT scan of subjects from Aim 1. Findings of this project will inform our long-term goal to develop the new generation of passive BSEs for older adults that are comfortable and effective for injury prevention and conduct of workplace tasks and routine activities requiring greater strength.