title: Influence of Input Hardware and Work Surface Angle on Upper Limb Posture in a Hybrid Computer Workstation.
abstract: OBJECTIVE
  We evaluated the effect of work surface angle and input hardware on upper-limb posture when using a hybrid computer workstation.
  
  
  BACKGROUND
  Offices use sit-stand and/or tablet workstations to increase worker mobility. These workstations may have negative effects on upper-limb joints by increasing time spent in non-neutral postures, but a hybrid standing workstation may improve working postures.
  
  
  METHODS
  Fourteen participants completed office tasks in four workstation configurations: a horizontal or sloped 15° working surface with computer or tablet hardware. Three-dimensional right upper-limb postures were recorded during three tasks: reading, form filling, and writing e-mails. Amplitude probability distribution functions determined the median and range of upper-limb postures.
  
  
  RESULTS
  The sloped-surface tablet workstation decreased wrist ulnar deviation by 5° when compared to the horizontal-surface computer when reading. When using computer input devices (keyboard and mouse), the shoulder, elbow, and wrist were closest to neutral joint postures when working on a horizontal work surface. The elbow was 23° and 15° more extended, whereas the wrist was 6° less ulnar deviated, when reading compared to typing forms or e-mails.
  
  
  CONCLUSIONS
  We recommend that the horizontal-surface computer configuration be used for typing and the sloped-surface tablet configuration be used for intermittent reading tasks in this hybrid workstation.
  
  
  CONCLUSIONS
  Offices with mobile employees could use this workstation for alternating their upper-extremity postures; however, other aspects of the device need further investigation.
authors.affiliation: University of Waterloo, Waterloo, Canada.
authors.forename: David C
authors.initials: DC
authors.lastname: Kingston
authors.affiliation: University of Waterloo, Waterloo, Canada.
authors.forename: Maureen F
authors.initials: MF
authors.lastname: Riddell
authors.affiliation: University of Waterloo, Waterloo, Canada.
authors.forename: Colin D
authors.initials: CD
authors.lastname: McKinnon
authors.affiliation: University of Arkansas, Fayetteville.
authors.forename: Kaitlin M
authors.initials: KM
authors.lastname: Gallagher
authors.affiliation: University of Waterloo, Waterloo, Canada callagha@uwaterloo.ca.
authors.forename: Jack P
authors.initials: JP
authors.lastname: Callaghan
mesh_terms: D000328:Adult; D003201:Computers; D004867:Equipment Design; D006804:Ergonomics; D005260:Female; D006801:Humans; D008297:Male; D011187:Posture / Q000502:physiology*; D013647:Task Performance and Analysis; D034941:Upper Extremity / Q000502:physiology*; D055815:Young Adult
keywords: computer interface; mobile devices; posture; sit-stand workstation; upper extremity