Ergonomists draw on the principles of their environment, industrial engineering, psychology, anthropometry, and biomechanics, physiology, psychology, and kinesiology to adapt the design of products and workplaces to people's sizes and shapes a well as their physical strengths and limitations. In doing so, the goal is to maximize the safety, comfort, and efficiency of the products in the workspace. Ergonomists also consider the speed with which humans react and how they process information, and their capacities for dealing with psychological factors. Armed with this complete picture of how humans interact with their environment, ergonomists develop the design that is theoretically the best for products and systems, ranging from the handle of a toothbrush to the flight deck of the space shuttle. An ergonomics task analysis can also help identify key components of surgical skill, ensuring that students have affordable, appropriate, valid, and reliable training.
The International Ergonomics Association (IEA) divides ergonomics into three domains, which deal with different aspects of ergonomics.
Physical ergonomics deals with the human body's responses to physical and physiological loads. Relevant topics include workstation layout, job demands, and risk factors such as repetition, vibration, force, and awkward/static posture as they relate to musculoskeletal disorders.
Cognitive ergonomics, also known as engineering psychology, concerns mental processes such as perception, attention, cognition, motor control, and memory storage and retrieval as they affect interactions among humans and other elements of a system. Relevant topics include mental workload, vigilance, decision-making, skilled performance, human error, human-computer interaction, and training.
Organizational ergonomics, or macroergonomics, is concerned with the optimization of sociotechnical systems within a workspace, including their organizational structures, policies, and processes. Relevant topics include shift work, scheduling, job satisfaction, motivational theory, supervision, teamwork, telework and ethics.
One training program that cultivates ergonomic skills is the Alexander technique. It has a long history of helping people develop the subtle coordination of thought and physical action required to monitor and alter harmful patterns of posture and movement. In short, it enables individuals to put ergonomic principles into practice, and thus helps them reduce their risk of developing a repetitive strain injury.
Ergonomists view people and the objects they use as one unit, and ergonomic design blends the best abilities of people and machines. Humans are not as strong as machines, nor can they calculate as quickly and accurately as computers. Unlike machines, humans need to sleep, and they are subject to illness, accidents, or making mistakes when working without adequate rest. Nevertheless, machines are also limited - cars cannot repair themselves, computers do not speak or hear as well as people do, and machines cannot adapt to unexpected situations as well as humans. An ergonomically designed system provides optimum performance because it takes advantage of the strengths and weaknesses of both its human and machine components.
Understanding human limitations early in the development of medical devices can reduce errors and avoid performance problems exacerbated by stress and fatigue. Using ergonomics in a design process may reduce the costs of procuring and maintaining products. It may also minimize the incidence of injury or longer-term malaise from poor working environments.
Many ergonomic problems associated with computer workstations occur in the shoulder, elbow, forearm, wrist, and hand. Continuous work on the computer may expose soft tissues in these areas to repetition, awkward postures, and forceful exertions, especially if the workstation is not set up properly. For example, the mouse device is present in virtually every office environment and designed specifically to the contours of either the right or left hand. Placing the mouse, trackball, or other input device too far away, too low, or too much on one side can cause shoulder, wrist, elbow, and forearm discomfort; however, they offer natural comfort and maximum hand-to-eye coordination when placed within the immediate reach zone.
The Office of Health and Safety at the Center for Disease Control (CDC) has identified repetitive motion injuries as a factor in employee injuries. Repetitive stress injury, also called repetitive strain injury, is an injury caused by overuse of muscles, tendons, and nerves. Usually, it affects the muscles, tendons, and nerves in the arms and upper back; hence it is also known as work related upper limb disorder (WRULD). The medically accepted reason it occurs is when muscles in these areas are kept tense for very long periods of time, due to poor posture and/or repetitive motions. It is most common among assembly line and computer workers. Good posture and ergonomic working conditions may help prevent or halt the progress of the disorder; stretches, strengthening exercises, and massages training to reduce neck and shoulder muscle tension can help heal existing disorders.
