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The pointing device or the mouse is now available in the market in different sizes, shapes, and configurations. Apart from the conventional mouse, other pointing devices include touch pads, trackballs, fingertip joysticks, and pucks. While designing a safe workstation, you should give great importance to selection and positioning of pointer/mouse. Do keep in mind the following factors while evaluating your workstation.
1) Pointer Placement
2) Pointer Size, Shape, and Settings
Pointer/Mouse Guidelines
1) Ensure that the pointer/mouse is close to the keyboard.
2) Ensure that you use alternate hands while handling the pointer/mouse.
3) Learn and use the keyboard short cuts to reduce extended use.
Pointer Placement
Probable Risks
If
the pointer/mouse is not placed near the keyboard, there are chances
that your body will be exposed to awkward postures, contact stress, or
forceful hand exertions while operating the device. If you continue to
work in such postures for long hours, your shoulders and arms will be
stressed out. For convenience you might sit with awkward wrist and
shoulder postures that might lead to musculoskeletal disorders in the
long run.
Feasible Solutions
o
Select a particular position for the pointer/mouse so that you can
maintain a straight, neutral wrist posture. If required, you may make
slight adjustments in your chair, desk, keyboard tray, etc.
o
If the keyboard tray/surface that you use does not have enough space
for both the keyboard and the mouse, you can try out the following
suggestions:
i) You can use a mouse platform over the keyboard that helps you to use the mouse above the 10-key pad.
ii) You can set up a mouse tray next to the keyboard tray.
iii)
You can se a keyboard that has a pointing device, such as a touch pad,
incorporated into it so that the work gets done even without the help
of the mouse.
iv) You can try using a keyboard without a ten-key pad, which leaves more room for the pointer/mouse.
v) You can install keyboard trays that are big enough to accommodate both the keyboard and mouse.
vi) You can try a mouse pad with a wrist/palm rest to promote neutral wrist posture.
vii) You can substitute keystrokes hence depending less on the mouse, such as Ctrl+S to save, Ctrl+P to print etc.
Pointer Size, Shape, and Settings
Probable Risks
If
the size and shape of the pointers that you choose are unsuitable, it
may force you to sit in awkward postures, thereby increasing stress and
hence overexertion. Generally, pointing devices that are too big or too
small make the fingers to apply more force and bend the wrist to
awkward positions. Also, if you operate a device designed for the right
hand with your left hand, it leads to posture disorders that can create
contact stress to the soft tissue areas in the palm of the hand.
Contact stress leads to irritation and inflammation.
Feasible Solutions
o
The pointing device has to be selected to the fit the hand of the user
who will be using it mostly. Pointing devices to fit right and left
hands as well as small and large hands are available in the market. It
is ideal to select a pointing device that is designed for either hand
because you can switch from one hand to the other while operating the
device hence giving rest to one hand at a time. Before selection of the
device, it is better to test it and ensure proper fit and feel.
o
The size of the device matters and hence while selecting you need to
ensure that you have to apply only a minimum force to generate
movement. Normally puck devices should be small in size for using with
single hand with a width of 1.5 to 2.5 inches, length of 2.5 to 4.5
inches, and a height of 1 to 1.5 inches.
o
It is better to reduce your dependence on the pointing device by using
short cut keys and other options available on the keyboard like page down thereby reducing the strain on hands.
o
Try out other pointing devices like joystick, touch pad, or trackball
that fits your hand better and doesn.t require bending the wrists when
you grip the device. Remember to try out new products prior to
selection and long-term use.
Fig. 11-wrist/palm rest for keyboard
Wrist / palm rest makes the positioning of the hand over the keyboard comfortable.
Probable Risks
If the sensitivity of the input device is not set properly, you tend to
use more force and awkward hand postures to control it. For example, a
very sensitive mouse may require excessive and extended finger force
for good control. If the sensitivity of the mouse is not enough, you
need to deviate the wrist in a wider angle
to move the pointer to your desired place. When you exert your wrist
forcefully for a long time or bend it repeatedly to place the pointer,
your hand and arm muscles get fatigued increasing the risk of
musculoskeletal injuries.
Feasible Solutions
o
The speed of the pointer may be defined as the pace in which it moves
on the screen when you move the pointing device with the hand. The
pointing device that you select should be sensitive and fast enough so
that you can comfortably adjust and control it as required. Also, the
pointer should cover the entire screen of the monitor while your wrist
is relaxed in a straight, neutral posture.
o
In order to control the pointing device with a light touch without
straining your wrist, it is better to set its sensitivity. Devices in
which the sensitivity can be adjusted through the computer control
panel are now available in the market.
o Do not grip the mouse/pointing device tightly in order to get good control of it.
o
If you are using a trackball, ensure that its exposed surface are is
not less that 100 degrees. It has to comfortably rotate in all
directions for the user to try any combination of movement as required.
Mouse/Pointing Device Recipe
- The
mouse/pointing device should be selected based on the requirements of
your job and your physical restrictions. Other than preference, there
is no much difference between a mouse, trackball, and other pointing
devices.
- The
cord of the mouse should be long enough to be conveniently placed near
the keyboard. The shape and size of the mouse should be good enough to
snug into the curve of your hand.
- Among
the different pointing devices, if you prefer a trackball for your
work, remember not to select the ones that need your thumb for rolling
its ball. This can cause discomfort and possible injury to the area
around your thumb.
- .If the user.s hands are small, then
select a mouse that is smaller than the normal ones. But if multiple
users are using it, then a normal-sized one should be retained.
- Always go for a mouse that has good sensitivity adjustments and that can be used by both hands conveniently.
Wrist/Palm Supports
If
your keyboard and mouse are arranged properly and appropriately, then
you can say that your workstation is a comfortable and productive one.
This comfort is intensified if you use wrist or palm rests. If used
properly, wrist/palm supports reduce muscle activity while working on
the computer and facilitates neutral wrist angle.
Fig. 12 - Palming the mouse makes the wrist straight.
Wrist Rest Guidelines
To
keep the contact stress that can occur while typing and while using the
mouse to a minimum, it is better to use a wrist rest so that you can
maintain straight wrist postures.
Probable Risks
o
The wrists tend to bend in a wider angle if you use the keyboard for
long hours without using a wrist rest. As the angle of bend increases,
the contact stress and irritation on tendons and tendon sheathes also
increases. Professionals who depend more on keyboards to get their job
done have to be very careful. The contact stress between the wrist of
the user and the hard/sharp components in the workstation also
increases.
o
The motion of the wrist is slowed down while you are resting the
wrist/palm on a support during the typing jobs that will in turn lead
to awkward wrist postures.
Feasible Solutions
o
Ensure that your hands are moving freely and are raised above the
wrist/palm rest while using the keyboard. Also remember that the pad
should be in touch with the palm of your hand and not your wrist while
resting on the wrist rest.
o Ensure that these are part of a well-designed workstation.
o
Do not frequently bend your wrists by adjusting other workstation
components like that chair, desk, or the keyboard. See to it that your
wrists are in a straight, neutral posture.
o The wrist support should be matched with the width, height, and slope of the front edge of the keyboard.
o
The wrist/palm supports should be fairly soft and rounded to minimize
pressure on the wrist. Ideally it should be at least 1.5 inches (3.8
cm) deep.
Wrist Rest Recipe
- The shape, width, slope, and height of the wrist rest should match the front edge of the keyboard.
- It would be better to use gel type materials for the padding that makes it soft and firm.
3. The
recommended depth of the wrist rest is at least 1.5 inches (depth away
from the keyboard). This helps to minimize contact pressure on the
wrists and forearm. Learn more about Healthy Computing habits.
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Note: While every care is taken
to provide medically accurate and up to date information in this web
site, it is to be noted that this advice is not intended to replace the
advice of your physician. Before undertaking the advice contained in
this web site, you should consult a medical professional.
Other pages on healthy computing: Awkward Postures
chairs Cts Exercises Eyestrain
Lighting Monitors Msd
Other Computer Hazards Telephones Ventilation
Work Station Setup
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