Birgit Juul-Kristensen, Brian Clausen, Inge Ris , Rikke Vikær Jensen , Rasmus Fischer Steffensen, Shadi Samir Chreiteh , Marie Birk Jørgensen , Karen Søgaard
Research Unit for Musculoskeletal function and Physiotherapy, University of Southern Denmark, 5230 Odense M, Denmark. E-mail: bjuul-kristensen@health.sdu.dk
DOI: 10.2340/16501977-1120

Objective: To investigate neck muscle activity and postural control in patients with whiplash-associated disorder compared with healthy controls.
Design: Cross-sectional study with convenience sampling.
Subjects: 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.
Conclusion: 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.