Purpose: This study aimed at investigating the effects of different body positions and axial loads on spinal stiffness to better understand spinal stabilisation mechanisms.
Methods: The posterior-to-anterior lumbar and thoracic spinal stiffness of 100 young healthy adults (mean age 23 years; 50 females) were measured in three test situations: prone, standing and standing while carrying a load equal to 50% of the subject's body weight. Each test situation comprised three trials.
Results: Spinal stiffness in all test situations showed good reliability. Repeated measures analysis of covariance showed significantly higher spinal stiffness in standing than in the prone position [F(1/1694) = 433.630, p < 0.001]. However, spinal stiffness was significantly lower when standing while carrying a load of 50% of the body weight than when standing without additional load [F(1/1494) = 754.358, p < 0.001].
Conclusion: This study showed that spinal lumbar and thoracic stiffness increases when body position is changed from prone to standing. Additional axial load of 50% of the subject's body weight results in reduced spinal stiffness during standing. These slides can be retrieved under Electronic Supplementary Material.
Keywords: Load; Lumbar; Spine; Stiffness; Thoracic.