Belt effects on lumbar sagittal angles

Objective. The study examined the belt effects on the change of lumbar sagittal angles. Design. The effects of pelvic and lumbar belts on lumbar sagittal angles were examined both radiographically and videographically in standing, erect sitting, and slump sitting. Background. The resulting changes of lumbar angles when wearing belts with different mechanical characteristics should be different. Methods. Eighteen healthy male subjects participated in this study. L1/L3, L3/L5, L5/S1 and L1/S1 were measured with the aid of lateral radiographs. The external joint angles were also measured via the motion analysis system. Results. Radiographic data revealed an interactive effect between working posture and the use of a belt (P < 0.046) on the change of L1/S1. In standing, both belts increased L1/S1 by increasing almost all the lumbar vertebral angles. In erect sitting, wearing lumbar belt had no effect but the pelvic belt decreased L1/S1 mainly through a decrease in L1/L3. In sitting slump with trunk flexion of 15°, both belts increased L1/S1 and restricting the movement of the pelvis. Conclusions. Belt effect to the change of lumbar sagittal angles in posture which involve knee flexing and/or trunk flexing seems not as the same as in standing posture.