Difference in movement coordination and variability during Five-Repetition Sit-to-Stand between people with and...

Chronic low back pain (CLBP) affects people's activities of daily living, including sitting down and standing up. Movement pattern analyses during five-repetition sit-to-stand (5RSTS) may allow CLBP status differentiation. 44 CLBP and 22 asymptomatic participants performed 5RSTS in this study, with their trunk and lower limb movements recorded using 3-dimensional motion capture system. Joint active range of motion, joint maximal velocity, joint and segment continuous relative phase (CRP) were analyzed. Mean absolute relative phase (MARP) and deviation phase (DP) variables were calculated in CRP analysis. Between-group kinematic variables were compared using One-way Multivariate Analysis of Covariance (MANCOVA). Significant variables from different methods were compared using binomial logistic regression to assess accuracy for CLBP status. Results showed that segmental CRP is the most sensitive method for CLBP assessment, with the CLBP group femur-to-pelvis and lumbar-to-pelvis movement coordination was more in-phase MARP (F(8,56) = 7.127, p < 0.001, Wilks'Λ = 0.441, ηp² = 0.559) and stable DP (F(8,56) = 4.585, p < 0.001, Wilks'Λ = 0.551, ηp² = 0.449) during both standing up and sitting down. Utilizing CRP variables yielded Nagelkerke R² = 0.708 and overall correct classification of 93 % for CLBP status. Individuals with CLBP exhibited distinct movement coordination and stability, which should be considered in CLBP assessments and intervention. Variable combination from the segment analysis was found to be the most predictive to CLBP status, and significantly different to the results obtained from joint analysis, highlighting the necessity for CRP method standardization in future studies.