title: Association between numbers of long periods with sustained low-level trapezius muscle activity and neck pain.
abstract: The purpose of this prospective cohort study was to evaluate relationships between sustained low-level muscle activity (SULMA) in the neck and pain after 1 year among machine operators of forest harvesters (n = 19), forwarders (n = 20) and forest researchers (n = 20). Surface electromyography of the right upper trapezius muscle was measured during one working day. Continuous muscle activity (SULMA periods) were analysed in predetermined time intervals. Neck pain was assessed by the Borg's category-ratio scale and the Standardized Nordic Questionnaire (dichotomised into pain duration <or=30 or >30 d). Harvesters reported significantly more pain than researchers. A higher number of long SULMA periods >8 min duration increased the risk of neck pain >30 d during the successive year (odds ratio 3.0, 95% CI 1.2-7.8). Perceived personal economy above average was associated with less pain, while other potential confounders or intermediate variables were not significant. Low-level trapezius muscle activity in periods longer than 8 min may constitute a risk for neck pain.
authors: Department of Production, Technology and Processing, Norwegian Forest and Landscape Institute, As, Norway. tove.ostensvik@skogoglandskap.no
authors: Tove
authors: T
authors: Ostensvik
authors: Kaj Bo
authors: KB
authors: Veiersted
authors: Petter
authors: P
authors: Nilsen
mesh_terms: D000328:Adult; D015331:Cohort Studies; D004576:Electromyography; D006804:Ergonomics; D005500:Follow-Up Studies; D016468:Forestry; D006801:Humans; D008297:Male; D008328:Man-Machine Systems; D008875:Middle Aged; D009334:Neck Muscles / Q000503:physiopathology*; D019547:Neck Pain / Q000503:physiopathology*; D009664:Norway; D009784:Occupational Diseases / Q000503:physiopathology*; D010147:Pain Measurement; D011446:Prospective Studies; D013997:Time Factors; D014940:Work Schedule Tolerance; D016526:Workload