The effect of sagittal hip angle on lumbar and hip coordination and pelvic posterior shift during forward bending.

Abstract

The purpose of this study was to investigate the effects of dynamic sagittal hip angle on lumbar and hip coordination and pelvic posterior shift during forward bending. A total of 44 asymptomatic younger female volunteers were recruited to this study. Following measurement of trunk forward bending, participants were divided into three groups based on hip flexion angle: group 1, < 30°; group 2, ≥ 30° and < 50°; and group 3, ≥ 50°. Lumbar spine and hip coordination and pelvic backward shift were recorded during trunk forward bending using a three-dimensional ultrasonic motion analysis system. Pelvic and total angles increased with hip angle (group 3 > group 2 > group 1; p = 0.003 and p < 0.001, respectively), whereas lumbar/hip and pelvic/hip angle ratios decreased significantly (p < 0.001). The degree of pelvic posterior shift increased to a limited extent, whereas the pelvic posterior shift/hip angle ratio decreased significantly (p < 0.05). Asymptomatic subjects with limited hip flexion showed reduced total pelvic anterior rotation and greater relative proportion of pelvic motion than insufficient hip motion. These subjects tended to increase the pelvic posterior shift/hip angle ratio during trunk forward bending, possibly increasing passive tension by elongating the hamstring muscles to increase hip motion. The results of this study provide information that will improve the assessment of lumbar spine and hip coordination patterns and facilitate movement strategies by determining the specific requirements of individuals. These slides can be retrieved under Electronic Supplementary Material.