title: Shoulder muscle activity in young and older people during a computer mouse task.
abstract: OBJECTIVE
  Assessment of the age effect in relation to computer work.
  
  
  BACKGROUND
  Increasingly, more older people are using computers, while hardware and software are not designed with special consideration of their needs.
  
  
  METHODS
  Eight young and nine older females performed different computer mouse tasks. Shoulder muscle activity was recorded from the right deltoid muscle, right and left upper trapezius muscle, and the neck extensor muscles.
  
  
  RESULTS
  Mean trapezius muscle activity was significantly higher in the older people (2.8%/3.7% EMG(max) for R/L) compared to the young (1.1%/1.2% EMG(max)). There was a tendency to a higher activity in the older people for the deltoid muscle and the neck extensor muscles. There were small differences in shoulder muscle activation levels between mouse actions, target directions, and between precision demands.
  
  
  CONCLUSIONS
  Shoulder muscle activity during computer work is affected by age, but only to a minor extent by the type of computer mouse task. The deltoid and the trapezius muscle activities are low during computer mouse use when there is efficient forearm support by the table. RelevanceAn increasing number of people use computers for hours every day. Intensive use of computers increases the risk of development of work-related musculoskeletal symptoms in the shoulder region.
authors.affiliation: Department of Physiology, National Institute of Occupational Health, Lerso Parkalle 105, DK-2100, Copenhagen, Denmark. bl@ami.dk
authors.forename: B
authors.initials: B
authors.lastname: Laursen
authors.forename: B R
authors.initials: BR
authors.lastname: Jensen
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D001696:Biomechanical Phenomena; D016287:Computer Peripherals; D004576:Electromyography; D005260:Female; D006801:Humans; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000502:physiology*; D012782:Shoulder / Q000502:physiology*; D013647:Task Performance and Analysis