Energy transfer across the lumbosacral and lower-extremity joints in patients with low back pain during sit-to-stand

Objective: To examine the transfer of energy through the pelvis and the lower limb during sit-to-stand (STS) in low back pain (LBP) subjects with or without a straight-leg raise sign. Design: Cross-sectional. Setting: Biomechanics laboratory. Participants: Three groups, each of 20 subjects, participated. The first group consisted of asymptomatic subjects, and the other 2 groups of consisted of LBP subjects (duration between 7 days and 12 weeks) with and without a straight-leg raise sign. Interventions: Not applicable. Main Outcome Measures: The work done and the power of the pelvis, thigh, and leg segments during STS were determined. Results: Energy was transferred from the pelvis to the thigh segment and then to the leg segment, and this was achieved mainly by passive mechanisms. The power flow of the pelvis segment was significantly decreased in subjects with LBP. Although the power of the lower-limb segments was decreased, the total work done of these segments was increased. Conclusions: STS is a more energy-demanding and less efficient task for subjects with LBP, either with or without a positive straight-leg raise sign. Such increases in energy demand may further exacerbate back pain, and treatment should be developed to restore a more efficient energy transfer pattern.