Patients with chronic non-specific low back pain have altered movement coordination during functional reaching tasks

Identifying altered motor control patterns during functional movements in patients with chronic non-specific low back pain (LBP) has important clinical implications for reducing the risk of recurrence. While prior research has shown that magnitudes of lumbar and hip motion are not altered in patients with chronic non-specific LBP, it is possible that outcomes which describe coordination could provide greater discriminatory information between pathological and healthy movement.

Determine the effect of biological sex and chronic non-specific LBP on coordination between hip and lumbar motion during cyclic and discrete reaching.

Twenty participants with chronic non-specific LBP (11 male/9 female, 23.5 ± 4.9 years old) and 21 control participants (12 male/9 female, 22.9 ± 6.1 years old) completed discrete and cyclic reaching tasks to a target in the mid-sagittal plane, while whole-body kinematics were collected using a three-dimensional motion capture system. Movement time, lumbar motion, hip motion, and the ratio between lumbar and hip motion were compared between participants with and without chronic non-specific LBP and between men and women using two-way mixed ANOVAs.

Participants with chronic non-specific LBP had reduced lumbar-hip ratios relative to control participants during both the cyclic (F = 4.779, p = 0.035, η² = 0.114) and discrete tasks (F = 4.743, p = 0.036, η² = 0.119), however group differences were not observed for hip or lumbar excursion during either task (p > 0.05). Participants with chronic non-specific LBP had slower reaching times relative to controls during the discrete reaching task (F = 4.795, p = 0.035, η² = 0.115). No significant effects of sex, and no interactions between group and sex were observed for any outcome.

Reduced lumbar-hip ratios during reaching likely reflect a compensatory movement strategy that could play an important role in the development and progression of LBP.