Comparison of Spine–Pelvis Kinematics Variability during Sit-to-Stand and Stand-to-Sit in People with & without Chronic Low Back Pain: A Vector Coding and Statistical Parametric Mapping Approach

There is evidence in the literature to suggest that low back pain may change spine–pelvis coordination during activities of daily living. This study aimed to compare the variability of the spine–pelvis coordination during sit-to-stand in people with and without LBP. Ten healthy individuals with a history of LBP and ten individuals without history of LBP participated in this study. Three-dimensional kinematic data of the upper trunk (UT), lower trunk (LT), lower back (LB), and pelvis segments during sit-to-stand and stand-to-sit were recorded using a multi-segmental spine and pelvis models using a motion capture system. The coordination patterns and the variability of the adjacent segments (UT, LT, LB, and pelvis) were calculated using the modified vector coding method that was implemented through a custom MATLAB code. An independent sample t-test was utilized to assess the differences in the coordination pattern, and a statistical parametric mapping method was used to quantify the differences in coordination variability between the two groups. The results indicate that there are some differences in coordination patterns between groups during sit-to-stand and stand-to-sit. However, a significant difference in coordination variability was only observed during sit-to-stand. The results showed that LBP can alter the kinematics coordination even in the upper (pain-free) parts of the spine during sit-to-stand by changing the coordination between UT and LT in a way that can lead to an increase in the loading on these segments. Additionally, people with LBP showed more coordination variability during sit-to-stand, which can be associated with a coordination strategy that facilitates an optimal and possibly pain-free coordination pattern.