Computer input devicesPrint

Ergonomic computer equipment: your health is in your hands

Professional use of a computer increasingly entails the use of efficient peripheral equipment. The mouse and the keyboard are two of the most important input devices. Incorrect use and frequently unergonomical devices are increasingly the cause of health problems, as both place an undue burden on the spinal column (particularly the cervical spine), the muscles and joints (primarily shoulder and hand). These massive strains, possibly also in combination with stress, can make the user ill in the long term.

This is detrimental to output and quality while increasing the periods of absence for sick leave. It even has a negative impact on the user's own quality of life, at the latest when the problems become chronic.

Positive mental attitude and back-friendly design of the workplace

The question here is how can these problems be dealt with? The fact is, the more countermeasures that are taken, the greater the probability of finding the solution. Here too we have to learn to relax, to cope properly with negative stress; supervisors must act as a role model with a humane approach to leadership, and we must move more – in the workplace and also in our leisure time, etc.

Further, indispensable help comes from designing the whole workplace according to ergonomic, back-friendly aspects. This includes among others the lighting, available space, room climate, even the colour scheme in the room, the furnishings and naturally also ergonomically designed, user-friendly keyboards and mouse devices to relieve the pressure on the user instead of compounding the problems.

Computer mouse

The mouse should permit an ergonomically appropriate working position that counteracts problems in the wrist joint and in the linked chain of joints and muscles through to the cervical spine.

Keyboard

An ergonomic keyboard allows the user to hold his or her hands in a physically appropriate way, thus helping to prevent tension- and stress-related pain in the first place.

Short distance between hands and spinal column

When handling all these input devices, as a general rule the upper and lower arm should preferably be held at right angles to keep the load of the arm as close as possible to the spinal column. In this context it is naturally also important to consider the height of the working surface, the desk and the adjustment of the chair.

Every increase in distance between hands and spinal column results in higher static strain which can cause problems in the long run. It is beneficial to the health to keep the input devices as close as possible to the body. The so-called "long arm" position frequently causes problems in the shoulders. The further the hand is from the body, the greater the strain in the cervical column. This can cause stress and tension in the long run. It must be possible to rest the wrist joints in relaxed fashion when not entering data on the computer, e.g. with an integrated wrist support.

Final remarks

Computer input devices are part of a comprehensive VDU workplace system. Their functionality depends on the ergonomic design of the whole system.

Checklist

The computer mouse in brief

• The mouse must be anatomically suitable for the hand, i.e. it must correspond to the functional/anatomic/topographic shape of the palm and to the size of the hand. In other words, it should fit the hand comfortably without bending the fingers or having a disruptive effect.
• It must be possible to operate the mouse easily with minimum force. It is important for the mouse to permit differentiated (changing) use of the hand and finger muscles.
• Task-specific use of the mouse should be possible on differently structured working surfaces (background).
• It should be possible to use the mouse with different fingers (e.g. index finger, middle finger). One-sided use of the index finger for typical click movements should be reduced, e.g. by using other fingers for the same function. If necessary, a third mouse button should be available for users with sensomotoric restrictions.
• Scrolling must be possible with a wheel operated with the middle finger resting in a relaxed position.
• There must not be any delays in transmission when using the mouse to access a required text field or a sign on the screen. Otherwise the user applies additional force by reflex when moving the mouse to reinforce the input command. This kind of psychological and physical reaction can cause muscular tension in the shoulders and wrists. The mouse should be used intuitively and in accordance with the specific tasks. Transmission of the mouse movements to the cursor on the screen should be as expected, i.e. direct.
• It must be possible for left-handed people to use the mouse, i.e. different models or corresponding configuration adjustment.

Minimum requirements

• The mouse must be anatomically suitable for the hand
• The hand is relaxed when placed on the mouse
• The mouse must be suitable for hands of different sizes
• The mouse must have a scrolling wheel
• The mouse must permit targeted, precise work activity in line with expectations
• It must be possible to adjust the reaction speed of the mouse to the user's individual way of working
• Easy to use, with differentiated use of the finger and hand muscles
• Also available for left-handed persons or with corresponding adjustments

Also appropriate

• Additional third mouse button
• Different materials can be used to position the hand in the expected way
• Full functionality must be possible even without a mouse pad
• Surface materials prevent additional persipration
• Visual design makes users want to work with the mouse
• More information is available for ergonomic use

The keyboard in brief

• It must be possible to use the keyboard holding the arms near to the body with the shoulders relaxed. The height and angle of the keyboard can be adjusted to hold the hands in a natural curve over the keys for relaxed use of the keyboard.
• It must be possible to use the keyboard without bending the wrists. The lower arms are supported; while writing, the balls of the thumb or wrists have no contact with any interfering surface.
• The keys work easily. Short, easy key strokes are kind to joints, tendons, muscles and ligaments.
• Acoustic feedback from the keys should be clearly perceptible but not a nuisance or obtrusive.
• The keys must have clearly visible symbols. These symbols should be wear-resistant.
• The key symbols should contrast with their background. This facilitates interaction with the computer, promotes perception, is less tiring and causes less fatigue.

Minimum requirements

• The keyboard blocks are positioned for relaxed working close to the body, preventing bending in the wrists
• The palms can be rested during input intervals
• Acoustic and haptic feedback on pressing the keys
• Flexible use in the workplace
• Designed to be easy to get used to
• Stable position
• Free of pollution

Also appropriate

• Visually appealing
• Can be easily handled by touch typists and non-touch typists without having to learn
• More information is available for ergonomic use

Products in this sector with the AGR seal of approval