title: Influence of chronic back pain on kinematic reactions to unpredictable arm pulls.
abstract: BACKGROUND
  There is evidence that muscle reflexes are delayed in patients with chronic low back pain in response to perturbations. It is still unrevealed whether these delays accompanied by an altered kinematic or compensated by adaption of other muscle parameters. The aim of this study was to investigate whether chronic low back pain patients show an altered kinematic reaction and if such data are reliable for the classification of chronic low back pain.
  
  
  METHODS
  In an experiment involving 30 females, sudden lateral perturbations were applied to the arm of a subject in an upright, standing position. Kinematics was used to distinguish between chronic low back pain patients and healthy controls.
  
  
  RESULTS
  A calculated model of a stepwise discriminant function analysis correctly predicted 100% of patients and 80% of healthy controls. The estimation of the classification error revealed a constant rate for the classification of the healthy controls and a slightly decreased rate for the patients.
  
  
  CONCLUSIONS
  Observed reflex delays and identified kinematic differences inside and outside the region of pain during impaired movement indicated that chronic low back pain patients have an altered motor control that is not restricted to the lumbo-pelvic region. This applied paradigm of external perturbations can be used to detect chronic low back pain patients and also persons without chronic low back pain but with an altered motor control. Further investigations are essential to reveal whether healthy persons with changes in motor function have an increased potential to develop chronic back pain.
authors.affiliation: Motionscience, Institute of Sport Science, Friedrich-Schiller-Universität Jena, Jena 07749, Germany. Electronic address: Martin.Goetze.1@uni-jena.de.
authors.forename: Martin
authors.initials: M
authors.lastname: Götze
authors.affiliation: Motionscience, Institute of Sport Science, Friedrich-Schiller-Universität Jena, Jena 07749, Germany; Institute of Solid Mechanics, Technische Universität Braunschweig, Braunschweig 38106, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Ernst
authors.affiliation: Motionscience, Institute of Sport Science, Friedrich-Schiller-Universität Jena, Jena 07749, Germany; National Institute of Occupational Health, Oslo 0033, Norway.
authors.forename: Markus
authors.initials: M
authors.lastname: Koch
authors.affiliation: Motionscience, Institute of Sport Science, Friedrich-Schiller-Universität Jena, Jena 07749, Germany.
authors.forename: Reinhard
authors.initials: R
authors.lastname: Blickhan
mesh_terms: D000328:Adult; D001132:Arm / Q000502:physiology*; D001696:Biomechanical Phenomena; D059350:Chronic Pain / Q000503:physiopathology*; D005260:Female; D006801:Humans; D017116:Low Back Pain / Q000503:physiopathology*; D008161:Lumbosacral Region / Q000503:physiopathology; D008875:Middle Aged; D009068:Movement; D010388:Pelvis / Q000503:physiopathology; D011187:Posture / Q000502:physiology
keywords: Chronic low back pain; Classification; External perturbations; Kinematics; Motor control