Dynamic Stability of the Trunk During Unstable Sitting in People With Low Back Pain

Abstract

Study Design. Cross-sectional study.Objective. To evaluate the dynamic stability and kinematics of the trunk during unstable sitting, and to determine the differences in these biomechanical parameters between healthy and low back pain (LBP) participants.Summary of Background Data. LBP patients exhibited alterations in trunk kinematic while performing different dynamic tasks and in static posture as a result of pain. It is not clear if changing in trunk motion may reduce postural control and the ability to perform a balancing task.Methods. Twenty-three LBP participants and thirty-one healthy participants were requested to sit on a custom made swinging chair and to regain the balance after tilting the chair backward for 10º and 20º. Lumbar spine, pelvis and chair motion were recorded using Fastrak sensors. The thoracolumbar curvature of all participants was also evaluated in standing position. The angular displacement of the chair was fitted in an equation describing the under-damped second order response to a step input.Results. Kinematic analysis showed that the hip range of motion (ROM) increased while spine ROM angle decreased in LBP participants for both tilt angles (p<0.05). There were no significant differences between the two subject groups in the time required to regain balance, and the natural frequency and damping ratio of the kinematic equation. Lumbar lordosis significantly decreased in LBP group.Conclusion. LBP participants showed trunk postural and movement adaptations that seems to be compensatory strategies to decrease the risk of further injuries and aggravation of the symptoms, but their ability to regain the balance was not affected by LBP. Clinicians should encourage LBP patients to remain active while they are experiencing pain.

PMID:

 

24583732

 

[PubMed - as supplied by publisher]