Sit-to-stand (STD) and stand-to-sit (SIT) analysis can provide information on functional independence in daily activities in patients with low back pain (LBP). However, in order for measurements to be clinically useful, data on psychometric properties should be available. The main purpose of this study was to investigate intra-rater reliability of STD and SIT tasks in participants with and without chronic nonspecific LBP (CNLBP). The second purpose was to detect any differences in lumbar spine and hips sagittal plane kinematics and coordination between asymptomatic individuals and CNLBP patients during STD and SIT.

Twenty-three CNLBP patients and 23 demographically-matched controls were recruited. Ten markers were placed on specific anatomical landmarks. Participants were asked to perform STD and SIT at a preferred speed. Peak flexion angles, mean angular velocities, lumbar to hip movement ratios, and relative phase angles were measured. The procedure was repeated after 2h and 6–8 days. Differences between two groups were analyzed using independent t-test. Intraclass correlation coefficient (ICC 3,k), standard error of measurement (SEM), and limits of agreement (LOAs) were also estimated.

The ICC values showed moderate to excellent intra-rater reliability, with relatively low SEM values (≤10.17°). The 95% LOAs demonstrated that there were no differences between the measured parameters. Furthermore, CNLBP patients had limited sagittal plane angles, smaller angular velocities, and lumbar-hip discoordination compared to asymptomatic participants.

The results showed moderate to excellent test-retest reliability of STD and SIT analysis. Moreover, CNLBP patients had altered kinematics during STD and its reverse compared to asymptomatic participants.