A kinematic analysis for shoulder and pelvis coordination during axial trunk rotation in subjects with and without recurrent low back pain.

The purpose of this study was to compare the kinematics of the shoulder and pelvis based on range of motion (ROM), angular velocity, and relative phase (RP) values during trunk axial rotation. Nineteen subjects with recurrent low back pain (LBP) and 19 age-matched control subjects who are all right limb dominant participated in this study. All participants were asked to perform axial trunk rotation activities at a self-selected speed to the end of maximum range in a standing position. The outcome measures included ROM, angular velocity, and RP on the shoulder and pelvis in the transverse plane and were analyzed based on the demographic characteristics between groups. The LBP group demonstrated decreased ROM (p=0.02) and angular velocity (p=0.02) for the pelvis; however, there was no group difference for the shoulder girdle. The ROM difference between the shoulder and pelvic transverse planes had a significant interaction with age (F=14.75, p=0.001). The LBP group demonstrated a higher negative correlation between the shoulder (r=-0.74, p=0.001) and pelvis (r=-0.72, p=0.001) as age increased while no significant correlations were found in the control group. The results of this study indicated that there was a difference in pelvic rotation in the transverse plane between groups during axial trunk rotation. It would be important to coordinate postural stability between the shoulder and pelvic girdles during ambulation; however, the pattern of trunk movement decreased with age due to possible pelvic stiffness in subjects with recurrent LBP. Therefore, improved pelvic flexibility for coordinated trunk movement patterns would help subjects with recurrent LBP.