Burkhart K, et al. - In the present study, the researchers analyzed the impact of spaceflight and subsequent on-Earth recovery on lumbar spine bone density, vertebral strength, and risk for spine fracture using CT images of the lumbar spine (L1 and L2) in 17 long-duration crewmembers. Vertebral strength was evaluated via CT-based finite element analysis (CT-FEA) and spinal loading during different activities via subject-specific musculoskeletal models. The results of this study indicate persistent deficits in vertebral strength following long-duration spaceflight, and while the risk of vertebral fracture remains low for typical activities, there was a significant risk of vertebral fracture in some crewmembers for strenuous exercise which needs maximum effort.