Upper and lower lumbar segments move differently during sit-to-stand.

Sit-to-stand (STS) is a functional dynamic task, requiring movement of the lumbar spine, however, little is known about whether regional differences or between-gender differences exist during this task. The aim of this study was to confirm whether kinematic differences existed within regions of the lumbar spine during STS and also to determine whether between-gender differences were evident. An electromagnetic measurement device, recording at 25 Hz, determined how different lumbar spine regions (combined, lower and upper) moved during STS in 29 healthy participants (16 males, 13 females). Discrete outputs including mean range of motion (ROM), maximum and minimum were calculated for each lumbar spine region. Analyses of covariance (ANCOVA) with repeated measures were used to determine whether regional differences and between-gender differences were evident in the lumbar spine during STS. With the lumbar spine modelled as two segments, the lower lumbar (LLx) and upper lumbar (ULx) regions made different contributions to STS: F1, 27 = 21.8; p < 0.001. No between-gender differences were found with the lumbar spine modelled as a single region (combined lumbar: CLx), however, modelled as two regions there was a significant gender difference between the LLx and ULx regions: F1, 27 = 7.3 (p = 0.012). The results indicate that modelling the lumbar spine as a single segment during STS does not adequately represent lumbar spine kinematics and there are important gender differences. These findings also need to be considered when investigating STS in clinical populations.