title: Trunk stabilization during sagittal pelvic tilt: from trunk-on-pelvis to trunk-in-space due to vestibular and visual feedback.
abstract: The goal of this study was to investigate the human ability to stabilize the trunk in space during pelvic tilt. Upper body sway was evoked in kneeling-seated healthy subjects by angular platform perturbations with a rotation around a virtual low-back pivot point between the L4 and L5 vertebrae. To investigate motor control modulation, variations in task instruction (balance naturally or minimize trunk sway), vision (eyes open or closed), and perturbation bandwidth (from 0.2 up to 1, 3, or 10 Hz) were applied. Cocontraction and proprioceptive muscle spindle feedback were associated with minimizing low-back flexion/extension (trunk-on-pelvis stabilization), while vestibular and visual feedback were supposed to contribute to trunk-in-space stabilization. Trunk-in-space stabilization was only observed with the minimize trunk sway task instruction, while the task instruction to balance naturally led to trunk-on-pelvis stabilization with trunk rotations even exceeding the perturbations. This indicates that vestibular feedback is used when minimizing trunk sway but has only a minor contribution during natural trunk stabilization in the sagittal plane. The eyes open condition resulted in reduced global trunk rotations and increased global trunk reflexive responses, demonstrating effective visual contributions to trunk-in-space stabilization. On the other hand, increasing perturbation bandwidth caused a decreased feedback contribution leading to deteriorated trunk-in-space stabilization.
authors.affiliation: Biomechanical Engineering Department, Faculty of Mechanical, Maritime and Material Engineering, Delft University of Technology, Delft, The Netherlands; and.
authors.forename: Paul
authors.initials: P
authors.lastname: van Drunen
authors.affiliation: Biomechanical Engineering Department, Faculty of Mechanical, Maritime and Material Engineering, Delft University of Technology, Delft, The Netherlands; and.
authors.forename: Frans C T
authors.initials: FC
authors.lastname: van der Helm
authors.affiliation: MOVE Research Institute Amsterdam, Department of Human Movement Science, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands.
authors.forename: Jaap H
authors.initials: JH
authors.lastname: van Dieën
authors.affiliation: Biomechanical Engineering Department, Faculty of Mechanical, Maritime and Material Engineering, Delft University of Technology, Delft, The Netherlands; and R.Happee@tudelft.nl.
authors.forename: Riender
authors.initials: R
authors.lastname: Happee
mesh_terms: D000328:Adult; D025461:Feedback, Physiological; D005260:Female; D006801:Humans; D008297:Male; D009119:Muscle Contraction; D018482:Muscle, Skeletal / Q000294:innervation / Q000502:physiology; D010388:Pelvis / Q000293:injuries / Q000502:physiology*; D004856:Postural Balance; D011597:Psychomotor Performance; D014722:Vestibule, Labyrinth / Q000502:physiology*; D014796:Visual Perception
keywords: lumbar spine; muscle spindles; postural control; system identification; visual and vestibular feedback