Ergonomics Mouse

8/2/2019 Ergonomics Mouse

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Occupational

Safety and

Health

NAME MATRIX NO.

MUHAMMAD FARHAN BIN JAHRONI 15DKA11F2052

MOHAMMAD FAIZ BIN 15DKA11F2080


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Occupational Safety and Health Page 1

Contents

Introduction .................................................................................................................................................. 2

Objective ....................................................................................................................................................... 3

Methodology ................................................................................................................................................. 4

Conclusion ................................................................................................................................................... 14

References .................................................................................................................................................. 15


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Ergonomics About Mouse

Introduction

Ergonomics is concerned with the fit between the user, equipment and their environments. It

takes account of the user's capabilities and limitations in seeking to ensure that tasks,

functions, information and the environment suit each user.

To assess the fit between a person and the used technology, ergonomists consider the job

(activity) being done and the demands on the user; the equipment used (its size, shape, andhow appropriate it is for the task), and the information used (how it is presented, accessed, and

changed). Ergonomics draws on many disciplines in its study of humans and their

environments, including anthropometry, biomechanics, mechanical engineering, industrial

engineering, industrial design, information design, kinesiology, physiology and psychology.

Typically, an ergonomist will have a BA or BS or BD in Psychology, Industrial/Mechanical

Engineering or Industrial Design or Health Sciences, and usually an MA, MS or PhD in a related

discipline. Many universities offer Master of Science degrees in Ergonomics, while some offer

Master of Ergonomics or Master of Human Factors degrees.

According to the International Ergonomics Association within the discipline of ergonomics there

exist domains of specialization:[1]

Physical ergonomics: is concerned with human anatomy, and some of the anthropometric,

physiological and bio mechanical characteristics as they relate to physical activity.

Cognitive ergonomics: is concerned with mental processes, such as perception, memory,

reasoning, and motor response, as they affect interactions among humans and other

elements of a system. (Relevant topics include mental workload, decision-making, skilled

performance, human-computer interaction, human reliability, work stress and training as

these may relate to human-system and Human-Computer Interaction design.)

Organizational ergonomics: is concerned with the optimization of socio technical systems,

including their organizational structures, policies, and processes.(Relevant topics include

communication, crew resource management, work design, design of working times,

teamwork, participatory design, community ergonomics, cooperative work, new work

programs, virtual organizations, telework, and quality management.)
http://en.wikipedia.org/wiki/Anthropometryhttp://en.wikipedia.org/wiki/Biomechanicshttp://en.wikipedia.org/wiki/Mechanical_engineeringhttp://en.wikipedia.org/wiki/Industrial_engineeringhttp://en.wikipedia.org/wiki/Industrial_engineeringhttp://en.wikipedia.org/wiki/Industrial_designhttp://en.wikipedia.org/wiki/Information_designhttp://en.wikipedia.org/wiki/Kinesiologyhttp://en.wikipedia.org/wiki/Physiologyhttp://en.wikipedia.org/wiki/Psychologyhttp://en.wikipedia.org/wiki/International_Ergonomics_Associationhttp://en.wikipedia.org/wiki/Ergonomic#cite_note-IEA_def-0http://en.wikipedia.org/wiki/Ergonomic#cite_note-IEA_def-0http://en.wikipedia.org/wiki/Cognitive_ergonomicshttp://en.wikipedia.org/wiki/Human-Computer_Interactionhttp://en.wikipedia.org/wiki/Participatory_Ergonomicshttp://en.wikipedia.org/wiki/Participatory_Ergonomicshttp://en.wikipedia.org/wiki/Human-Computer_Interactionhttp://en.wikipedia.org/wiki/Cognitive_ergonomicshttp://en.wikipedia.org/wiki/Ergonomic#cite_note-IEA_def-0http://en.wikipedia.org/wiki/International_Ergonomics_Associationhttp://en.wikipedia.org/wiki/Psychologyhttp://en.wikipedia.org/wiki/Physiologyhttp://en.wikipedia.org/wiki/Kinesiologyhttp://en.wikipedia.org/wiki/Information_designhttp://en.wikipedia.org/wiki/Industrial_designhttp://en.wikipedia.org/wiki/Industrial_engineeringhttp://en.wikipedia.org/wiki/Industrial_engineeringhttp://en.wikipedia.org/wiki/Mechanical_engineeringhttp://en.wikipedia.org/wiki/Biomechanicshttp://en.wikipedia.org/wiki/Anthropometry


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Objective

Abstract Computer users who experience repetitive wrist movements and awkward

hand positions are prone to developing upper extremity disorders. Manufacturers havedesigned various ergonomic mice in response to complaints of pain and discomfort

related to computer mouse use. The objective of this work was to validate the use

of surface electromyography (sEMG) in assessing the design of non-keyboard input devices

(computer mice). While holding the computer mouse in different grasp positions sEMG of

the forearm and hand were recorded during a set of static tasks.

The sEMG signal provided information regarding the level of muscle activity and the varied

combinations of muscular effort needed to position the hand in a specified posture. Asignificant decrease in the level of sEMG activity was observed for the pronator

muscles when subjects were tested using ergonomic computer mice. The sEMG-based

method was validated to be sensitive to the impact of subtle differences in shape/design on

the amplitude of the surface EMG data. We also proved a significant effect of hand

size and grasp position on the level of muscle activity associated with different mice.


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Methodology

Twenty-one healthy subjects were recruited in this study. Age ranged from 20 to 38 years with

a mean and standard deviation of 26.3 +/- 5.8 years. Ten of the subjects were female. Subjects

were recruited in order to cover a range of hand sizes from the 5th percentile of the female

population to the 95th percentile of the male population

Muscle selection in this study was based on several criteria. The first criterion was that the

muscle of interest had to be detectable by surface electrodes. Secondly, the recorded activity

was reproducible in any environment and eventually could be applied to a field investigation.

EMG signals were recorded from the following muscles of the forearm and the hand: Extensor

Carpi Ulnaris (ECU), Extensor Digitorum (ED), Pronator Quadratus (PQ), Pronator Teres (PT),

Flexor Digitorum Superficialis (FDS), First Dorsal Interosseus (FDI), and Second Dorsal

Interosseus (SDI) muscles. These muscles were chosen because they are the dominant muscles

that control the handto assume the three tested positions. Fig. 1 shows the position of the

electrodes on the forearm and hand of one subject. A single and double differential electrode is

Fig. 1. Electrode placement on the forearm.


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implemented based on the muscle of interest zone (Fig.2).

Fig. 2. Single and double differential electrodes

When measuring activity of the wrist/finger extensor muscles that are in close proximity with

one another it is ideal to use double differential electrodes. The double differential also called

three-bar electrode is preferred for localized areas because it removes neighboring muscle

signals from the signal of interest. Single differential electrodes are used when high selectivity is

not a main concern (bicep, quadriceps, calf, etc.). The sEMG signals were detected with a

Bagnoli- 8- channel system (Delsys Inc.). In order to provide an output range of 0.1-1 V (peak to

peak) the sEMG signals were amplified with a gain of 1000 or 10,000. The sEMG signal was then

filtered at a bandwidth of 20 to 450 Hz and sampled at 1024 Hz using a 12-bit Analog to Digital

conversion board. The modified signal was then stored in computer memory.

The study was performed using the following four computer mice: Logitech Mouse, Logitech

Mouse Man, Microsoft IntelliMouse and Microsoft IntelliMouse Pro. The Logitech Mouse and

Microsoft IntelliMouse were chosen because they are commonly found at college computer

terminals and are standard in desktop computer packages. The criterion for choosing the

Microsoft IntelliMouse Pro was its ergonomic feature. Logitech was the first to provide slanted

mice to reduce the flat, handsdown posture (forearm pronation) typical with mouse use. As a

result we decided to test the Logitech Mouse Man.


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In order to compare computer mouse designs it was necessary to specify hand positions that

were the same across tests performed with different computer mice. Three static positions of

the hand, corresponding to three different ways of holding the computer mouse, were tested:

1) rest [Fig. 3]; 2) side grip [Fig. 4]; 3) grab position

Fig.3. Rest

Fig.4. Side Grip

Fig. 5. Grab


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10 Tips for Using a Computer Mouse

The following tips should help you avoid a mouse-related musculoskeletal injury. The same

posture principles apply to other input devices (e.g. trackball, touchpad, pen, digitizing pucketc.). Postural variation is a key factor for good ergonomics. Try to regularly vary your posture

when you work with a mouse, and in this way you will help to minimize the risk of ergonomic

problems. remember, the best ergonomic mice are designed to allow you to vary your posture

while working with the mouse.

1. Mouse Grip - don't throttle your mouse (it's already dead)! Hold the mouse gently to

move it over a mousing surface.

2. Mouse from the Elbow - don't skate or flick the mouse with your wrist. Make controlled

mouse movements using your elbow as the pivot point and keep your wrist straight and

neutral.

3. Optimal Mouse position- sit back in your chair, relax your arms then lift your mousing

hand up, pivoting at the elbow, until your hand is just above elbow level. Your mouse

should be positioned somewhere around this point. Don't use a mouse by stretching to

the desk or out to the side of a keyboard. With a flat mouse platform, position this 1-2"

above the keyboard and over the numeric keypad if you are right handed - you can

easily move it out of the way if you need to access these keys. With a downward sloping

mouse platform, position this close to the side of the keyboard so that you can use the

mouse in a neutral wrist position. Position adjustable mouse platforms are commercially

available (e.g. Humanscale, Flexrest, 3M etc.)

4. Protect your wrist - if you look at the anatomy of the wrist it is curved away from any

contact surface (you can easily see this by resting your hand/arm on a flat surface -

you'll see light under the wrist and can probably even pass a thin pen under this). The

forearm is shaped liked this for the wrist to remain free of surface pressure contact.

5. Avoid restricting circulation - For may people there are exposed blood vessels near the

skin at the wrist, which is where the pulse is often taken. Any pressure in this region will

disrupt circulation into the hand and this will increase the risks of injury.


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6. Don't use a Wrist Rest - research has shown that using a wrist rest doubles the pressure

inside the carpal tunnel, because the floor of the tunnel is a more flexible ligament that

transmits external pressure changes directly into the carpal tunnel (the roof of the

tunnel is bone so the pressure doesn't get transmitted on through the hand). Indeed,

one test for carpal tunnel syndrome (CTS), know as Tinel's sign, simply involves tappingon the palmar surface of the wrist, which is enough to cause tingling and numbness in

someone developing CTS.

7. Avoid Restricting Arm Movement - with a softly padded wrist rest, especially one that is

rounded, or a soft chair arm rest the forearm becomes "locked" into position and this

encourages people to make mouse movements by flicking the wrist, which also

increases intracarpal pressure.

8. Keep the Mouse Free Moving - The base of the palm of the hand is the part of the body

designed to support the hand when resting on a surface. For keyboard use a broad palm

support is best. However, mouse use is different from keyboard use. With a keyboard

the best posture is for users to float their hands over the keyboard when typing and

then to rest on the palm support in microbreaks between typing bursts. You can use

rest-breaking software (e.g.Break reminder etc) to help track and advise on your mouse

use. With mousing this doesn't happen. A mouse is used by moving its position over a

surface, and resting usually occurs when mouse movements stop but with the mouse

still being held in the hand. Mouse movements should be made using the elbow as the

pivot point, not the wrist. Anything that impairs free movement of the forearm/hand

and mouse will increase injury risks.

9. Mouse shape - choose a mouse design that fits your hand but is as flat as possible to

reduce wrist extension. Don't use a curved mouse. Use a symmetrically shaped mouse.

Consider a larger mouse and there are several new interesting products on the market ,

such as the Whale mouse or the Perfit mouse, that encourage arm rather than wrist

movements or that encouirage postural variety and one or two-handed use. Pen-based

mice designs also allow a more comfortable grip. Some types of mouse palm support

can be attached to the mouse, such as the Mouse Bean.

10.Load sharing - if you want to load share between your right and left hands, that is using

the mouse for some of the time with each hand. For this you need to choose a mouse

platform that can easily be configured to the left or/and right, and a symmetrical shaped

mouse that can be used by either hand.


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Other input devices - whether you choose a different mouse design, a trackball, a joystick, a

pen, a touchpad, a multitouch pad or some other input device, make sure that your position

this comfortably, and that your wrist is in a neutral position when using the device.

It is believed by many researchers that by

keeping your wrist and hand in line with

your forearm in a straight and neutral

position, you reduce stress and strain on

tendons and muscles.

When cradling the mouse, use your index

and middle fingers for clicking the right and left mouse buttons, respectively.

Make sure, when handling the mouse, to keep your hand in a straight line with your forearm,

and not surrender to any urge to bend the palm at the writs; either to the left or right, or up or

down.

If your wrists form an unhealthy angle when using the mouse, it can easily cause many aches

and pains, as well as joint and/or tendon infections.

Even though there is no problem using a

standard mouse in a correct and healthy

way,several new models of ergonomic

mice have been designed. The most

successful ergonomic mice of all time are,

of course, the tracking ball mice series by

Logitech, which is used by moving a ball

by ones thumb instead moving the entiremouse. There are some newer advances, such as the joystick styled mouse by 3M and the new

patented Evoluent mouse.
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Some ergonomic practical tips:

The mouse should be held loosely and should fit naturally under the palm of your hand.

Avoid the use of a wrist pad.

Movement of the mouse should come from the whole arm and shoulder, not just the

wrist. The mouse should be positioned at the same height as the keyboard and directly

adjacent to avoid reaching (if there is at a wider angle than 110 degrees between your

arm and forearm, this is considered reaching).

Avoid holding the index finger elevated between clicks.

Whether you spend five minutes or five hours using your mouse or trackball, these suggestions

can help you stay comfortable and productive.

Recent research suggests that long periods of repetitive tasks or an improperly set-up

workspace may lead to physical discomfort or injury to hands, wrists, arms, neck, or back. If you

feel pain, numbness, weakness, swelling, burning, cramping, or stiffness in these areas, see a

qualified health professional.


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Make sure that your workspace is set up properly...

Your keyboard should be directly in front of you with your mouse or trackball sitting next to it.

Your elbow should be next to your side. Place your mouse or trackball within easy reach.

You do not need to use a mouse pad with a high- performance mouse. If you choose to use amouse pad anyway, be sure to consider the thickness of the mouse pad when you set up your

workspace, because a mouse pad may raise your mouse higher than your elbow.

Do

Do adjust the height of your chair and table to have the mouse or track-ball at elbow

height.

Do have your elbow next to your side with your forearm parallel to the floor or slightly

bent down. Position your keyboard and mouse/trackball so you do not have to reach.


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Keep your shoulders, arms, wrists, and hands relaxed and comfortable as you work...

To keep your shoulders, arms, wrists, and hands relaxed as you work, let them hang loosely at

your sides for a moment, allowing them to dangle toward the floor and to become relaxed. Try

to maintain this relaxed feeling while you work.

When you are ready to use your mouse or trackball, avoid resting your wrists on sharp edges,

or on your desktop.

As you use your mouse or trackball, make sure that your elbow is next to your side. Keep your

wrist relaxed and straight - don't bend it up, down, or to either side. Keep your shoulders

relaxed. Do not hunch or shrug.

Take Breaks

Get up and walk around at least twice every hour. Some studies suggest staying too long in one

position - or repeating the same motion many times - may cause discomfort and injury. Do

something different with your hands and arms for a while. Vary your tasks throughout the day.


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Rest your hand lightly on the mouse or trackball

You'll find it easier and more comfortable to get the control you want if you're not squeezing

the mouse or trackball too tightly.

Be alert to signs of discomfort

Contact a doctor if you experience pain, tenderness, swelling, burning, cramping, stiffness, or

numbness in your fingers, hands, wrists, arms, or shoulders.

However excellent the functionality of the standard computer mouse - we all use it with great

ease - most of the time it is too small for the hand while its shape forces your hand and fingers

in an unnatural gripping position. It lacks comfort and the gripping and pinching, as well asthe hovering of your fingers above the mouse buttons are the major sources of complaints

which may lead to Repetitive Strain Injury (RSI) or Carpal Tunnel Syndrome.

The Research team has also tested a vertical mouse and found that gripping and pinching of a

vertical mouse is still a potential source of RSI or Carpal Tunnel Syndrome. Another medical

university found that with a vertical mouse the"interosseus membrane" is extremely taut

("stressed") which also may lead to complaints.

The HandShoe Mouse was developed with all complaints in mind. Support of your hand and

fingers prevents gripping and pinching and your arm is supported at the ideal angle of 25-30degrees which makes sure your forearm is completely relaxed. So, you will understand that the

HandShoe Mouse is the latest technology in the Evolution of the computer mouse as shown

here:


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Conclusion

If you are using your mouse on a surface then:

Best arrangement for a mouse is a platform over the number keypad and just above the

keyboard.

Good arrangement is a pad on an angled platform to the side of the keyboard.

Poor arrangement is a flat surface to the side of the keyboard

Worst arrangement is on the desk out to the side of the keyboard.


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References

INTERNET

www.wikipedia.org

www.safecomputertips.com

BOOKS

Ben-Gal, I., & Bukchin, J. (2002). The ergonomic design of workstation using virtual

manufacturing and response surface methodology. IIE Transaction, 34.

Garg, A., Chaffin, D.B., & Herrin, G.D. (1978). Prediction of metabolic rates for manual

materials handling jobs. American Industrial Hygiene Association Journal, 39 (8), 661-

674.

Karhu, O., Karkonen, R., Sorvali, P., & Vepsalainen, P. (1981). Observing working

postures in industry: examples of OWAS application. Applied Ergonomics 12 (1), 13- 17.

Myers, R. H., & Montgomery, D. C. (2002). Response surface methodology. 2nd edition.

John Wiley & Sons. New York, NY.

Scott, G.B., & Lambe, N.R. (1996). Working practices in a perchery system using the

OWAS. Applied Ergonomics 27 (4), 281- 284.

Waters, T. R., Putz-Anderson, V., Garg, A. and Fine, L. J. (1993). Revished NIOSH

equation for design and evaluation of manual lifting tasks. Ergonomics, 36(7), 749-776.

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