title: Effect of head-mounted displays on posture.
abstract: OBJECTIVE
  The aim of the present study was to determine if a wearable system based on a head-mounted display (HMD) causes users to alter their head position and adopt postures that place greater stress on the musculoskeletal system.
  
  
  BACKGROUND
  HMDs are common output devices used with wearable computers. HMDs provide the wearer with visual information by projecting computer-generated virtual images in front of the eyes. Deviations of neck posture from a neutral upright position increase the stresses on the musculoskeletal system of the head and neck.
  
  
  METHODS
  Seven paramedics simulated the treatment of a patient under a normal condition and when using an HMD wearable computer system. During the simulations a posture analysis was performed using the Rapid Upper Limb Assessment method.
  
  
  RESULTS
  The postures adopted when wearing an HMD, as compared with a normal condition, scored significantly higher for the neck (z = 2.463, p < .05) and for overall body posture (left side of the body: z = 2.447, p < .05; right side of the body: z = 2.895, p < .05).
  
  
  CONCLUSIONS
  Wearing an HMD can force the wearers to modify their neck posture. As such, the musculoskeletal system of the head and neck may be placed under increased levels of stress.
  
  
  CONCLUSIONS
  Potential users should be made aware that HMDs could dictate modifications in neck posture, which may have detrimental effects and may compound the weight effect of the HMD.
authors.affiliation: Electronic, Electrical and Computing Engineering, School of Engineering, The University of Birmingham, Birmingham, B 15 2TT, UK. j.f.knight@bham.ac.uk
authors.forename: James F
authors.initials: JF
authors.lastname: Knight
authors.forename: Chris
authors.initials: C
authors.lastname: Baber
mesh_terms: D000488:Allied Health Personnel; D003198:Computer Simulation; D003626:Data Display / Q000639:trends; D004867:Equipment Design; D006804:Ergonomics; D019416:Head Movements / Q000502:physiology*; D006331:Heart Diseases / Q000628:therapy; D006801:Humans; D008954:Models, Biological; D018763:Muscle Fatigue / Q000502:physiology*; D009142:Musculoskeletal Physiological Phenomena; D009333:Neck / Q000502:physiology / Q000503:physiopathology*; D011187:Posture / Q000502:physiology*; D013312:Stress, Physiological / Q000209:etiology / Q000503:physiopathology; D014584:User-Computer Interface; D016474:Weight-Bearing / Q000502:physiology*