The purpose of the study was to evaluate the lumbar mobility and flexibility by the vertical vibration stimulation. The subjects were 21 young adults were divided into vibration group (n = 7) that applied 30 Hz vibration stimulation to the lumbar, foam roller group (n = 7) that relaxes the lumbar muscles with a foam roller, and good morning exercise group (n = 7) that stimulates the lumbar spine with the good morning exercise. The muscle strength, EMG and the sit & reach test were measured, to evaluate the lumbar mobility and flexibility before and after exercise intervention in each group. Results showed increasing in the vibrating group in muscle strength and EMG, and the good morning group and the vibrating group in the Sit & Reach test. This can be developed as a new alternative to exercise therapy for spine rehabilitation.

Low back injury (LBI) often occurs during manual materials handling (MMH). Intradiscal pressure (IDP) is used to assess the risk of the LBI and is measured in vivo or by computer simulation. As for computer simulation, motion analysis and finite element (FE) analysis are usually employed. In this study, a FE model has been developed for L4-L5 segment with high risk of injury to predict LBI during manual lifting tasks. The FE model was composed of lumbar vertebrae, discs, and ligaments and a calibration process was performed to set the nonlinear material properties of the intervertebral disc. To validate the developed FE model, IDP and range of motion (ROM) under in vitro loading conditions were compared to the experiments and other FE studies in literature. Within in vitro range, IDP and ROM from the FE model were in agreement with results from previous studies. The FE model developed in this study can be scaled according to the subject used in the analysis integrating FE analysis to motion analysis, and is expected to be used in future work to estimate IDP and stress/strain in joint structures during occupational activities.

The incidence of adjacent segment degeneration (ASD) after lumbar spinal fusion have not been precisely verified. In the presence of mild degeneration in the proximal segment adjacent to the fused segment, selection of additional fusion is not agreed upon. Muscle activity change and ASD after fusion was analyzed with a developed three-dimensional finite element model of musculoskeletal system. The paraspinal muscle activities were calculated based on a hypothesis, the intervertebral disc was assumed to have a transducer function and the muscle is activated according to a sensor driven control mechanism to maintain the stability of the lumbar spine. Simulation was conducted for erect standing and 60° isometric forward flexed posture. Total muscle force produced in each deep muscle group was similar however activity of some muscle fascicles which inter-connected to the vertebrae above the fused segment showed increased value. In the presence of mild degeneration in the proximal adjacent segment, muscle activity across the degenerated segment was reduced. Despite changes in muscle activity, nucleus pressure at adjacent segment was increased in both cases. This change would eventually lead to the ASD.

Spinal stability is controlled by two interrelated systems: the spinal column including ligaments and the muscular control system. In addition to these systems, the thoracolumbar fascia (TLF) also interacts with the muscular system to maintain the stability of the spine. The effects of the tensioning of TLF on the spinal stability was investigated using computational analysis. The stability of the spine was analyzed with a three-dimensional finite element model of musculoskeletal system including TLF. The paraspinal muscle activities were calculated based on a hypothesis: the intervertebral disc was assumed to have a transducer function and the muscle is activated according to a sensor driven control mechanism to maintain stability of the lumbar spine. Muscle forces were calculated in examining 40o isometric forward flexed and erect standing postures. As a result, the fascial tension induced a decrease in superficial muscle activity while maintaining the spinal stability.