title: Height, surface firmness, and visual reference effects on balance control.
abstract: OBJECTIVE
  To investigate the effects of height, surface firmness, and visual reference on standing balance in construction workers.
  
  
  METHODS
  Controlled laboratory study with balanced repeated measures.
  
  
  METHODS
  Twenty four construction workers.
  
  
  METHODS
  Test subjects performed standing tasks at ground level as well as at 3 m and 9 m high balconies on firm or deformable surfaces with close visual references included or excluded from their visual field.
  
  
  METHODS
  Standing balance was determined from center of pressure as measured by a force platform. Dependent variables were root mean square of sway in medial-lateral and anterior-posterior directions, area of sway, and velocity of sway.
  
  
  RESULTS
  Heights without close visual references significantly increased all sway parameters. The effect of height in conditions without close visual references increased dramatically on deformable surfaces.
  
  
  CONCLUSIONS
  Elevated work environments and deformable work surfaces negatively affect balance and may be associated with increased risk of fall incidents. Appropriate close visual references increase the ability to maintain balance.
authors.affiliation: National Institute for Occupational Safety and Health, Division of Safety Research, Morgantown, West Virginia 26505-2888, USA. psimeonov@cdc.gov
authors.forename: P
authors.initials: P
authors.lastname: Simeonov
authors.forename: H
authors.initials: H
authors.lastname: Hsiao
mesh_terms: D000058:Accidental Falls / Q000517:prevention & control*; D000328:Adult; D005160:Facility Design and Construction; D006801:Humans; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D009784:Occupational Diseases / Q000517:prevention & control*; D016272:Occupational Health; D004856:Postural Balance / Q000502:physiology*; D011336:Probability; D011446:Prospective Studies; D011597:Psychomotor Performance / Q000502:physiology*; D012307:Risk Factors; D013499:Surface Properties; D014792:Visual Acuity; D014796:Visual Perception / Q000502:physiology*; D014947:Wounds and Injuries / Q000517:prevention & control*