Differences in movement variability may be related to a guarded response to pain or a less robust movement pattern, indicating a potential dysfunction in motor control. The study objective was to compare patterns of lumbo-pelvic coordinative variability, during repeated sit-to-stand-to-sit, in individuals with low back pain and healthy adults.Methods:
Participants were adults with low back pain (n = 16) and healthy controls (n = 21). Kinematics for the T12-L3, L3-S1, and hip segments were measured using electromagnetic motion capture during 10 sit-to-stand-to-sit trials. Continuous relative phase analysis using the Hilbert transform method determined coordination and variability of the Hip-L3S1, and L3S1-T12L3 segments, deconstructed into 4 periods (start/up/down/end). T-tests compared coordination and variability of the full task between groups, and a mixed ANOVA compared the effects of group and period for the two segments.Findings:
Across the full task, the low back pain group demonstrated more variable (mean difference = −6.95, 95% CI = −12.3 to −1.59) and greater out-of-phase behavior (mean difference = −22.6, 95% CI = −39.1 to −6.03) in the LHip-L3S1 segment. Group-period interaction effects revealed greater variability in the start period (mean difference = −0.325, 95% CI = −0.493 to −0.156) and more out-of-phase behavior in the start (mean difference = −0.350, 95% CI = −0.549 to −0.150) and end (mean difference = −0.354, 95% CI = −0.602 to −0.105) periods for the LHip-L3S1 segment.Interpretation:
Excessive variability may relate to reports of poor spinal proprioception in low back pain; however, based on our sample characteristics (low pain and disability) and lack of symptoms during the task, classifying our findings as dysfunctional may not be fully warranted.