Study design: A cross-sectional study to examine the sagittal kinematics of spine and lower limb movement during sit-to-stand (STS).
Objective: To describe the sagittal kinematics of the spine and lower limb in healthy older adults during STS from 2 seat heights.
Summary of background data: Older adults with age-related changes in the neuromusculoskeletal system are likely to have difficulty in STS. However, little is known about movement of the spinal regions and their interaction with the lower limb during STS, and the effect of seat height.
Methods: Thirty-two healthy older adults aged over 60 years were videotaped performing STS from 2 seat heights. A 2-dimensional video motion analysis system with a revised sagittal model was used to measure angular displacement and velocity for the cervical, thoracic, lumbar spine, and the lower limb joints.
Results: Concurrent flexion in the hip joint and lumbar spine was accompanied by extension in the thoracic, lower, and upper cervical spine as the trunk leaned forward. After the buttocks lifted off (LO) the chair, the movement interaction in the spine and hip joint was reversed. Some significant age-related changes during STS included downward head tilt at LO, decreased lumbar range of motion, and a large between-participant variation in the movement ratios. Statistically significant differences in the temporal parameters, angular displacement, and velocity were also found when standing from a lower chair.
Conclusion: This study provides a detailed description of STS in healthy older adults, which has implications for rehabilitation of elderly patients who have difficulty with this activity. Clinicians need to be aware of the concurrent contribution of the hip joint and lumbar spine to trunk forward lean, the importance of thoracic extension during the pre-LO phase and the downward gaze at LO in healthy older adults.