THE WORKSTATION CHAIR
Height needs to be set to ensure that the knees are bent just short of 90 degrees, with the feet on a firm surface. Either the floor or a footplate. If the seat can be tilted forwards than this helps extending the spine.
Seat depth needs to be appropriate for the thigh length. People with short thighs who sit in deep chairs have their hips pulled toward the front of the chair; causing PPT. Seat backs can be adjusted in/out to alter the seat depth. Back support needs to be set at the correct height for the lumbar spine. Often people have it set too low, and it only serves to push the pelvis forward. A full-length back support can help with trunk elongation and broadening of the upper trunk.
Arm rests. DO NOT rest your arms on these when typing. Use them to rest the arms on during a break.
Typing with the elbows on the armrest only increases the effort in the forearms and hands in the manual tasks being completed.
Matters are made worse for the muscles if it is a poor posture that they are being asked to maintain, as some muscle groups will then be stretched and weakened.
FURNITURE
Ill-fitting furniture will contribute to poor posture when it does not align and support the worker in proper anatomical positions. Chairs that are too high cause people to slouch as their pelvis slides forward in the chair with resulting flexing of the upper back. Poor backrests that do not support the lumbar spine do not reinforce elongation of the trunk.
TABLE
Table height is important. Too high and the wrists are being extended too much while the work is being undertaken. Too low and the upper trunk is bent forward as the hands reach down to the work area.
The table height must be such that the fingers are above the keyboard, dropping down on to the keyboard, with the hand in the same horizontal plane as the forearm. If the table cannot be raised, raising the chair and supplying a footplate will help establish the correct relationship between the hands and the work surface.
The table height should permit 2-3 inches clearance between its underside and the top of the thighs.
KEYBOARD
Do not elevate the back of the keyboard on its stand, This only causes wrist extension. If possible raise the front end of the keyboard, which will help promote a neutral position at the wrist.
Do not rest the wrist rests while typing, as it promotes over use of the small muscles of the hand, while the muscles of the upper arm are held in a rigid way. It is more desirable to hold the forearm and hand unsupported, using the larger muscles of the upper arm to move the hands across the keyboard.
THE MOUSE
Prolonged bracing of the shoulder, upper arm and forearm muscles while using a mouse, can lead to pains in neck, arm, and hands. Users are at risk from gripping the mouse too hard, with possible arthritis developing at the thumb. The mouse also forces the user to use one finger repetitiously. The user is also required to slide the mouse around and needs to be aware of the value of using the whole arm to do this, not just the small muscles of the hand.
Good mouse habits
• Hold the mouse lightly
• Do not rest your hand or forearm on the table when using a mouse – this reinforces wrist extension
• Use the entire arm to move the mouse, not just the hand
• Do not hold the thumb or pinkle off the mouse in an exaggerated manner
• Take frequent rest breaks
THE SCREEN
Make sure that the top of the monitor is level with your eyes. Ensure that any copy is at the same level, the same distance (20-24 inches) from the head with nothing beyond an arc of 45 degrees from the midline.
Eliminate glare from sun or artificial light sources – both can cause eyestrain.
You may need a separate small lamp to illuminate copy.
When taking regular rest breaks, look around out of the window, track objects as they move, focus on objects that are near and far away. |
