Hip joint mobility and spinal angles in standing and in different sitting postures

The spinal angles of 25 female subjects were measured in standing and in four different sitting postures with various trunk-thigh angles. Additionally, measurements of hip and lumbar mobility were made in an attempt to relate mobility to spinal curvature in the different sitting postures. Lumbar curvature was observed to decrease as the trunk-thigh angle decreased across the different sitting postures, and reduction in curvature was associated with hip mobility. An exploratory analysis of interrelationships among hip mobility, spinal mobility, and spinal curvature was also carried out. A significant correlation between lumbar and thoracic angular deviations in standing and hip flexion/extension range was obtained. The findings are discussed with reference to theories of sitting posture and the influence of hip joint mobility on postural adaptations to furniture. Further investigations, including studies of male subjects, are indicated.