Person-specific characteristics of people with low back pain moderate the movement pattern within motor skill training and strength and flexibility exercise: Secondary analysis of a randomized clinical trial

People with low back pain (LBP) display an altered movement pattern during functional activities. Exercise-based treatments improve the altered pattern, but there is individual variability in the response to treatment. This study investigates the moderating effect of person-specific characteristics on a movement pattern at baseline and change over time in the pattern in people with chronic LBP who received motor skill training (MST) or strength and flexibility exercise (SFE). Kinematic data were collected at baseline, immediately post-treatment, and 6 months post-treatment. Lumbar contribution (LC) to total movement was used to quantify the magnitude of the altered movement pattern. Hierarchical linear modeling was used to explore the moderating effects of treatment group, age, sex, duration of LBP, and baseline LC on 1) baseline LC and 2) the change in LC over time. We found that person-specific characteristics moderated the change over time in LC within MST. Older people had a smaller change over time in LC and did not retain the improved pattern as well as younger people (β = 0.01, SE = 0.004, p < 0.01). People with greater baseline LC had a greater improvement in LC compared to people with less baseline LC (β = -0.07, SE = 0.01, p < 0.01).