ERGONOMICS AND VDT’S

The introduction of video display terminals (VDT’s) has changed the way people work. VDT operators are able to work at a rapid pace using a limited number of muscles. Keystrokes result in prolonged and repetitive use of the the hands and arms, while other parts of the body remain immobilized.

Prolonged sitting subjects the shoulder, neck and back muscles to fatigue and stress. Bad posture can contribute to these problems. Too frequent too forceful strokes also contribute to potential injury to forearm, wrist and hand muscles, tendons and nerves.

Health problems associated with working at a VDT can be alleviated through the use of good work habits. These include maintaining good posture, refocusing the eyes, taking frequent rest breaks, exercising and proper configuration of the work station. Workers can maximize their comfort and maintain good posture by keeping a well organized work space with frequently used materials and equipment within easy reach.

Keyboard

The keyboard and pointing device position is the most important aspect of an ergonomic work station and should be the first adjustment made. Adjust the keyboard height so that the upper arm and forearm form a 100-110 degree angle at the elbow when the hands are placed on the keyboard. The shoulders and upper arms should be in a relaxed position at the side of the body. The wrist should be in a relaxed or neutral position, forming a straight line with the hand and forearm. Adjustable keyboard trays are often required to obtain correct positioning of the keyboard. The keyboard may need to be placed in either a positive or negative tilt depending on the worker’ posture and position in relationship to the keyboard. Wristrests can be used to keep the wrists straight and avoid pressure caused by hard and sharp surface and edges. However, it is important for the user to avoid static positioning of the rest on the wristrest when keying. This results in excessive movement of the wrist when keying. The wristrest should be used only as a rest between keying.

Screen Placement and Viewing

The position of the screen is a primary determinant of good posture. Adjust the height of the screen so that your neck is in a neutral and relaxed position when viewing the screen. The top of the monitor should be approximately at the same height or slightly lower than the top of your head. Lower heights are required if you wear bifocals. Incorrect positioning of the screen results in a slouched posture. Make sure the screen is positioned directly in front of you to avoid turning or twisting your neck and back. If you view your copy more frequently than your screen, place your copy directly in front of you.

The recommended distance between your eyes and the screen should be between 20 and 30 inches. Place copy documents on the side of the dominant eye and at the same height and angle as the screen to avoid unnecessary neck and shoulder strain. Document holders or bookstands can be used to attain correct positioning.

Adjust the angle and position of the VDT screen and keep it clean to minimize glare and character sharpness. Other techniques to minimize glare are: (1) modify overhead lighting with the use of filters or specialty lights; (2) close blinds or curtains over windows; (3) use anti-glare screens with minimal tinting (may reduce clarity). Overhead lighting can be replaced with indirect lighting. Tungsten floorlamps are good alternatives. However, safety precautions regarding fire hazards should be maintained.

Selection of a Proper Chair

Use a chair with adjustable seat height. The seat height should be adjusted so that the feet can rest flat and firmly on the floor. This assists is pushing the body back into the chair for proper lumbar support. A footrest may be necessary to accomplish this task in order to maintain proper height of the keyboard. Adjust the seat back angle and height to provide needed back support and comfort. Armrests are helpful to provide upper extremity support, but should allow for free movement of the body when working.

Ergonomic Pauses

Take short, frequent breaks and rest pauses in preference of longer, more frequent ones. Short pauses can prevent the accumulation of stress symptoms. Rest pauses should occur every 30 minutes and last for one minute. Rest pauses should incorporate exercises, stretches, and movement to increase blood flow and strengthen muscles.

Refocus the eyes periodically by looking away from the monitor at something in the distance. Blinking, yawning, moving the eyes up and down, left and right, etc., are also beneficial. Palming the eyes with your hands while resting for 20 second breaks is useful for many people