入浴姿勢の差異による体幹部の生体力学的負担の変化

抄録

Although several previous studies investigated bathing comfort from the viewpoint of thermal effect or physiology, few studies investigated that from the viewpoint of biomechanics. The objective of this study was to evaluate bathing postures from the biomechanical viewpoint. In the previous study, authors proposed a biomechanical model in bathing postures and shows that joint torque at the ankle and knee were changed due to bathing postures. However, joint torque in the hip joint was not changed significantly, although subjective score relating to relax in the abdomen was changed. In the present study, it was hypothesized that lumbar posture affected to biomechanical change in trunk because lumbar spine was curved characteristically in bathing. To evaluate trunk posture in detail, an improved biomechanical model was developed by focusing on lumbar. Bathing postures and reaction forces from the bathtub to a human were measured for ten healthy male subjects in two bathtub conditions (new bathtub and conventional one). A three-dimensional motion analysis system and 3D force plates were used to measure the experimental data. A biomechanical model in which a human body is represented as a link of body segments was constructed. The result showed that joint angle and joint torque in the lumbar was changed due to bathtub conditions. Change of joint torque in the lumbar corresponded to change of subjective score. These results suggest that the new model was useful for evaluating biomechanical load in trunk.