Ergonomics

Ergonomics is all about designing things to suit their users.
The design could be on a physical level, like making sure a chair, knife or shovel is easy to use for the task intended, or it could be on a psychological level, like making sure a computer program or instrument panel is easy to understand.
Ergonomics plays a particularly important role in making sure that safety critical industries like nuclear power stations can be controlled by their users, and in everyday life by making sure that workstations, checkouts, factory machinery can be used comfortably on a day to day basis.
Ergonomics is concerned with the 'fit' between people and their work. It takes account of the worker's capabilities and limitations in seeking to ensure that tasks, equipment, information and the environment suit each worker. What are the four areas of concern regarding computer egonomics?
How often should we have a break?
What angle should your elbows and knees be at when you are sitting at the computer?
http://www.youtube.com/watch?v=jbV5dGvJWyo&feature=relmfu
http://www.ergonomics.com.au/pages/400_useful_info/420_how_to_sit.htm