Sagittal spine and lower limb movement during sit-to-stand in healthy young subjects.

This study aimed to determine the sagittal movement relationships between thoracic, lumbar spine and hip joints during sit-to-stand (STS). Forty-seven healthy young adults were videotaped performing STS at their preferred speed from a chair set at 100% knee height. Forward trunk lean prior to buttock lift-off (LO) was accomplished by concurrent lumbar and hip flexion (1:3). As the lumbar spine flexed the thoracic spine extended, resulting in a LO trunk angle of 45.7 degrees (+/-5.8 degrees ) with respect to a horizontal reference. Following LO, the hip(s) and lumbar spine extended and the thoracic spine flexed, with the standing thoracic angle approximating the initial thoracic posture in sitting.