title: During computing tasks symptomatic female office workers demonstrate a trend towards higher cervical postural muscle load than asymptomatic office workers: an experimental study.
abstract: OBJECTIVE
  Do symptomatic female office workers perform computing tasks with higher cervical postural muscle loads (in terms of higher amplitudes and less muscular rest) and more discomfort compared with asymptomatic individuals? Are these differences in postural muscle loads consistent across bilateral (typing) and unilateral (mousing) conditions?
  
  
  METHODS
  an experimental case-control study.
  
  
  METHODS
  18 symptomatic female office workers and 21 asymptomatic female office workers.
  
  
  METHODS
  Three conditions (typing, mousing, and type-and-mouse) were performed in random order.
  
  
  METHODS
  Muscle load was measured as median amplitude and gap frequency using surface EMG of bilateral cervical erector spinae and upper trapezius. Discomfort was measured using a numerical rating scale.
  
  
  RESULTS
  The case group demonstrated 4.3% (95% CI 0.1 to 8.4) higher amplitude during typing and 3.5% (95% CI 0.1 to 6.9) higher amplitude during type-and-mouse in the right cervical erector spinae compared with the control group. There was a similar difference between groups in the left cervical erector spinae which also demonstrated a 1.2 gaps/min (95% CI -2.3 to 0.0) lower frequency during typing. The case group had significantly higher discomfort during all conditions compared with the control group. The case group demonstrated higher median amplitudes and lower gap frequencies than the control group during bilateral conditions (typing and type-and-mouse) compared with unilateral conditions (mousing) for both muscle groups.
  
  
  CONCLUSIONS
  There was increased amplitude and decreased muscular rest in the cervical erector spinae of office workers performing typing and mousing tasks. These findings may represent a mechanism underlying computer-related musculoskeletal disorders.
authors.affiliation: Rehabilitation Sciences, The Hong Kong Polytech University, Hung Hom, Kowloon, Hong Kong. rsgszeto@inet.polyu.edu.hk
authors.forename: Grace P Y
authors.initials: GP
authors.lastname: Szeto
authors.forename: Leon M
authors.initials: LM
authors.lastname: Straker
authors.forename: Peter B
authors.initials: PB
authors.lastname: O'Sullivan
mesh_terms: D000328:Adult; D016022:Case-Control Studies; D002574:Cervical Vertebrae / Q000502:physiology*; D003201:Computers; D005260:Female; D006801:Humans; D015994:Incidence; D008875:Middle Aged; D009334:Neck Muscles / Q000502:physiology*; D019547:Neck Pain / Q000453:epidemiology; D016272:Occupational Health; D017063:Outcome Assessment, Health Care; D011187:Posture / Q000502:physiology*; D016474:Weight-Bearing / Q000502:physiology