title: Increased neck muscle activity and impaired balance among females with whiplash-related chronic neck pain: a cross-sectional study.
abstract: OBJECTIVE
  To investigate neck muscle activity and postural control in patients with whiplash-associated disorder compared with healthy controls.
  
  
  METHODS
  Cross-sectional study with convenience sampling.
  
  
  METHODS
  Ten females with whiplash-associated disorder (age 37.7 years (21-58), neck pain > 2 years and neck disability index (NDI) > 10) and 10 healthy female controls (age 35.9 years (21-53), NDI < 6).
  
  
  METHODS
  Surface electromyography measured muscle activity of the anterior scalene, sternocleidomastoid, neck extensors and upper trapezius muscles, expressed as mean relative activity related to maximum voluntary electromyography (%MVE). On a force plate, 3 balance tasks (Romberg stance with open and closed eyes, 1-legged stance) and a perturbation task with sudden unloading, were performed. The total area, areas from slow and fast components, and range of displacements were calculated from decomposed centre of pressure anterior-posterior and medial-lateral signals.
  
  
  RESULTS
  During balance tasks with closed eyes and one-legged stance, the relative mean activity of all 4 muscles was significantly increased in whiplash-associated disorder compared with healthy controls. Postural sway was also significantly increased.
  
  
  CONCLUSIONS
  Increased neck muscle activity and increased postural sway during simple balance tasks indicate disturbed sensory feedback patterns in people with whiplash-associated disorder, which may have negative consequences when performing daily activities.
authors.affiliation: Research Unit for Musculoskeletal function and Physiotherapy, University of Southern Denmark, 5230 Odense M, Denmark. bjuul-kristensen@health.sdu.dk
authors.forename: Birgit
authors.initials: B
authors.lastname: Juul-Kristensen
authors.forename: Brian
authors.initials: B
authors.lastname: Clausen
authors.forename: Inge
authors.initials: I
authors.lastname: Ris
authors.forename: Rikke Vikær
authors.initials: RV
authors.lastname: Jensen
authors.forename: Rasmus Fischer
authors.initials: RF
authors.lastname: Steffensen
authors.forename: Shadi Samir
authors.initials: SS
authors.lastname: Chreiteh
authors.forename: Marie Birk
authors.initials: MB
authors.lastname: Jørgensen
authors.forename: Karen
authors.initials: K
authors.lastname: Søgaard
mesh_terms: D000328:Adult; D059350:Chronic Pain; D003430:Cross-Sectional Studies; D004576:Electromyography; D005260:Female; D006801:Humans; D008875:Middle Aged; D009334:Neck Muscles / Q000503:physiopathology*; D019547:Neck Pain / Q000503:physiopathology*; D004856:Postural Balance; D012678:Sensation Disorders / Q000503:physiopathology*; D014911:Whiplash Injuries / Q000503:physiopathology*; D055815:Young Adult