title: Spinal load changes during rotatory dynamic sitting.
abstract: OBJECTIVE
  To measure load and moment changes acting on the lumbar spine during rotatory sitting.
  
  
  BACKGROUND
  A new chair concept generating dynamic stimuli by alternating rotations in the horizontal plane of the chair's seat was recently developed.
  
  
  METHODS
  Load and moment changes were measured telemetrically with a spinal fixator device in vivo.
  
  
  RESULTS
  A rotatory frequency of 0.22 Hz with an amplitude of 1.8 degrees to the right and left side showed maximum axial force changes in the fixator of 23 N and maximum bending moment changes of 0.52 Nm.
  
  
  CONCLUSIONS
  Lumbar force and moment changes during dynamic sitting occur, although only one patient was included in the study. Reasons could be temporary muscular activation in order to adapt the body's equilibrium conditions at the end-point rotation. RelevanceOur measurements suggest that a rotatory chair does have an effect on lumbar spine forces. It becomes more likely that this concept could improve the discs' nutrition and may prevent low back pain.
authors.affiliation: Department of Orthopaedic Surgery, Philipps-University of Marburg, 35033 Marburg, Baldingerstrasse, Germany. lengsfel@post.med.uni-marburg.de
authors.forename: M
authors.initials: M
authors.lastname: Lengsfeld
authors.forename: D L
authors.initials: DL
authors.lastname: van Deursen
authors.forename: A
authors.initials: A
authors.lastname: Rohlmann
authors.forename: L L
authors.initials: LL
authors.lastname: van Deursen
authors.forename: P
authors.initials: P
authors.lastname: Griss
mesh_terms: D000328:Adult; D001696:Biomechanical Phenomena; D006801:Humans; D007374:Interior Design and Furnishings; D008159:Lumbar Vertebrae / Q000502:physiology*; D008297:Male; D011187:Posture; D012399:Rotation