title: Upper trapezius fatigue in carpet weaving: the impact of a repetitive task cycle.
abstract: BACKGROUND
  Shoulder disorders are one of the most prevalent musculoskeletal disorders among carpet weavers. The most important cause of these disorders is muscle fatigue. The aim of the present study is to investigate the effect of carpet weaving characteristics on upper trapezius (UTr) muscle fatigue during a task cycle.
  
  
  METHODS
  In this cross-sectional study, 9 women and 3 men participated. During an 80-min cycle of carpet weaving, a times-series model was applied to assess electromyography amplitude and frequency changes.
  
  
  RESULTS
  According to the joint analysis of electromyogram spectrum and amplitude method, the participants experienced 0% force decrease, 0.9% recovery, 18% force increase and 72% fatigue in the left UTr. Furthermore, the rates of force decrease, recovery, force increase and fatigue in the right UTr were 18%, 18%, 18% and 45%, respectively. Fatigue in the right and the left UTr was reported to be the dominant state during one carpet weaving task cycle.
  
  
  CONCLUSIONS
  Task cycle appears to have a significant impact on UTr fatigue in participants, and UTr fatigue can be considered a serious risk factor in shoulder musculoskeletal disorders. Hence, further studies should focus on better workstations and work-rest periods during various subtasks.
authors.affiliation: a Ergonomics Department , Hamadan University of Medical Sciences and Health Services , Iran.
authors.forename: Neda
authors.initials: N
authors.lastname: Mahdavi
authors.affiliation: a Ergonomics Department , Hamadan University of Medical Sciences and Health Services , Iran.
authors.forename: Majid
authors.identifier: http://orcid.org/0000-0001-8545-5845
authors.initials: M
authors.lastname: Motamedzade
authors.affiliation: b Physical Therapy Department , Iran University of Medical Sciences and Health Services , Iran.
authors.forename: Ali Ashraf
authors.initials: AA
authors.lastname: Jamshidi
authors.affiliation: c Environmental Health Research Center, Kurdistan University of Medical Sciences , Iran.
authors.forename: Ebrahim
authors.initials: E
authors.lastname: Darvishi
authors.affiliation: d Department of Biostatistics and Epidemiology , Hamadan University of Medical Sciences and Health Services , Iran.
authors.forename: Abbas
authors.identifier: http://orcid.org/0000-0002-3803-3663
authors.initials: A
authors.lastname: Moghimbeygi
authors.affiliation: a Ergonomics Department , Hamadan University of Medical Sciences and Health Services , Iran.
authors.forename: Rashid
authors.initials: R
authors.lastname: Heidari Moghadam
mesh_terms: D000328:Adult; D003430:Cross-Sectional Studies; D012090:Cumulative Trauma Disorders / Q000503:physiopathology; D004576:Electromyography; D006804:Ergonomics; D005260:Female; D005430:Floors and Floorcoverings; D006801:Humans; D007492:Iran; D008297:Male; D018763:Muscle Fatigue / Q000502:physiology*; D009784:Occupational Diseases / Q000503:physiopathology; D064171:Superficial Back Muscles / Q000503:physiopathology*; D013783:Textile Industry
keywords: Iran; ergonomics; muscle fatigue; surface electromyography; upper limb musculoskeletal disorders