title: The effects of work surface hardness on mechanical stress, muscle activity, and wrist postures.
abstract: BACKGROUND
  Contact pressure is a risk factor which can contribute to musculoskeletal disorders.
  
  
  OBJECTIVE
  The objective of the present study was to determine whether a work surface with a soft, pliable front edge could reduce contact pressure, muscle activity, and subjective musculoskeletal comfort, and improve wrist posture relative to a conventional, hard work surface.
  
  
  METHODS
  In a repeated-measures blinded experiment with eighteen subjects (8 females and 10 males), contact pressure, wrist posture, typing productivity, perceived fatigue, wrist and shoulder muscle activity, and subjective comfort were compared between the two different work surfaces during keyboard use, mouse use and mixed mouse and keyboard use.
  
  
  RESULTS
  The results showed that across the three modes of computer work, the contact pressure was lower on the soft-edge work surface compared to the conventional work surface (p's <0.03) and subjects reported to have less perceived fatigue in the forearms and wrists. No differences in muscle activity, wrist posture, and subjective comfort were measured between the two work surfaces.
  
  
  CONCLUSIONS
  Given the significant reduction in contact pressure and corresponding lower ratings in perceived fatigue, the soft-edge work surface subjectively and objectively improved measures of contact stress which may reduce physical exposures associated with the onset and development of musculoskeletal disorders.
authors.affiliation: Environmental and Occupational Health Program, Oregon State University, Corvallis, OR, USA.
authors.forename: Jeong Ho
authors.initials: JH
authors.lastname: Kim
authors.affiliation: Department of Environmental and Occupational Health Sciences, University of Washington, Seattle, WA, USA.
authors.forename: Lovenoor
authors.initials: L
authors.lastname: Aulck
authors.affiliation: Hyundai Dymos, Farmington Hills, MI, USA.
authors.forename: David
authors.initials: D
authors.lastname: Trippany
authors.affiliation: Department of Environmental and Occupational Health Sciences, University of Washington, Seattle, WA, USA.
authors.forename: Peter W
authors.initials: PW
authors.lastname: Johnson
mesh_terms: D000328:Adult; D016287:Computer Peripherals; D005260:Female; D006244:Hardness; D006801:Humans; D007374:Interior Design and Furnishings; D008297:Male; D018763:Muscle Fatigue; D018482:Muscle, Skeletal / Q000502:physiology*; D011187:Posture; D011312:Pressure; D016037:Single-Blind Method; D013314:Stress, Mechanical; D013499:Surface Properties; D014953:Wrist / Q000502:physiology*; D055815:Young Adult
keywords: Electromyography; contact pressure; electrogoniometer; office ergonomics