Study On The Influence Mechanism Of Office Chair Lumbar Support On Human Spinal Curvature

The biomechanical changes of the spine caused by sedentary office work are the main incentives for office workers to suffer from low back pain.Effective back support of office chairs can maintain the normal physiological curvature of the spine.In this study,the methods of inertial motion capture,surface electromyography and subjective comfort evaluation were used to quantify the spine curvature,muscle activation and subjective comfort under the different back support of office chairs.The main conclusions are as follows:(1)In the study of lumber protrusion on spine curvature,with the increase of lumber protrusion,the spinal flexion/extension of the subjects showed a trend of first decreasing and then increasing.The influence of the protrusion on the spine curvature was not significant(P = 0.64 ～ 0.92);the activation of the erector spinae showed a trend of first decreasing and then increasing;the subjective comfort of the waist first increased and then decreased.Therefore,it is recommended to control lumber protrusion within an appropriate range in the design of the lumbar support of the office chair.Excessive or too small lumber protrusion is not conducive to maintaining the normal physiological curvature of the spine.(2)In the study of mesh materials of office chair backrest on spine curvature,with the increase of the breaking strength of the mesh,the flexion degree of the subjects T9-T8,L1-T12,and L5-S1 cones decreased continuously.The tensile properties of the mesh material had a significant effect on the curvature of the thoracic and lumbar vertebrae(P = 0.0006);the activation of the erector spinae showed an increasing trend;the subjects felt more comfortable subjectively.Therefore,in the selection of the mesh material for office chair backrest,the mesh material with better tensile properties should be appropriately selected to maintain the normal physiological curvature of the spine.(3)In the study of backrest inclination on spine curvature,the influence of backrest inclination on spine curvature was significant(P = 0.03 ～ 0.04).When the backrest inclination was large(135°),the flexion/extension angles of the T9-T8,L1-T12,and L5-S1 cones were significantly smaller than those when the backrest inclination was small(115°);the flexion/extension angles of the C1-HEAD,T1-C7,and L4-L3 cones were significantly larger than those when the backrest inclination was small(115°);the overall activation of the erector spinae was reduced;and the subjects felt more comfortable subjectively.Therefore,a sitting posture with a large backrest inclination should be adopt to maintain the normal physiological curvature of the spine.