Lumbar–pelvic coordination in the sitting position

This study assessed the relationship of each movement direction on the lumbar spine and on the pelvis in regards to lumbar–pelvic coordination in the sitting position. Lumbar and pelvic motions were recorded using a flexible electrogoniometer in 12 healthy subjects during two different tasks in the sitting position. The coordination of the lumbar spine and pelvis was evaluated using the ratio of lumbar and pelvic angles (L/P ratio hereafter) in three motion phases. There were significant differences in the L/P ratio values between during the “forward bending” and “rising from a forward flexed position” phases (P < 0.01). The L/P ratio value (∼−0.7) was consistent during the movement from an erect to a slumped sitting position as the lumbar spine and pelvis moved in opposing directions. This study shows that lumbar–pelvic coordination occurs in the sitting position. Lumbar–pelvic coordination is confirmed even if the movement tasks are different in the sitting position, and these findings show that aspects of a particular movement are dependent on the given movement task. These findings may provide greater insight into the kinematic changes involved in lumber–pelvic coordination, and help clinicians implement sitting exercises conducive to the independence of the patient.