ergonomics - office workstation computer) ug- 2007

8/14/2019 Ergonomics - Office Workstation Computer) UG- 2007

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INDUSTRIALINDUSTRIAL

ERGONOMICSERGONOMICSOffice-WorkstationOffice-Workstation

(Computer workstation)(Computer workstation)DR. SITI ZAWIAH MD. DAWALDR. SITI ZAWIAH MD. DAWAL

DEPT. OF ENGINEERING DESIGNDEPT. OF ENGINEERING DESIGN

AND MANUFACTUREAND MANUFACTUREUNIVERSITY OF MALAYAUNIVERSITY OF MALAYA


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IntroductionIntroduction

It is common now and accepted that oneIt is common now and accepted that one

should sit in the office.should sit in the office.

Yet, low back pain and musculoskeletalYet, low back pain and musculoskeletaldiscomfort and together with eye-straindiscomfort and together with eye-strain

constitute the majority of subjectiveconstitute the majority of subjective

complaints and objective symptoms ofcomplaints and objective symptoms of

computer operators.computer operators.


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Theories of Healthy StandingTheories of Healthy Standing

The normal or healthy standing wasThe normal or healthy standing wasrecommended by Staffel in 19recommended by Staffel in 19thth century.century.

It has been used by physicians, mothers,It has been used by physicians, mothers,

teachers, orthopedists etc.teachers, orthopedists etc.Even today that upright or straightEven today that upright or straightstanding posture with slight lordosesstanding posture with slight lordoses

(forward bends) are considered as good(forward bends) are considered as goodand proper , healthy, balanced andand proper , healthy, balanced andneutral neutral


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Theories of Healthy SittingTheories of Healthy Sitting

At least a century it was common beliefAt least a century it was common beliefthat standing and sitting with a straightthat standing and sitting with a straightback is physically desirable and socialback is physically desirable and socialproper for pupils and adults alike.proper for pupils and adults alike.

Apparently, human body is adapted toApparently, human body is adapted tochange to moving about.change to moving about.

Sitting or standing still for extendedSitting or standing still for extended

periods is uncomfortable and leads toperiods is uncomfortable and leads tocompression of tissues, reduction incompression of tissues, reduction inmetabolism and deficiency in bloodmetabolism and deficiency in blood

circulation in the lower legs.circulation in the lower legs.


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Good Working PositionsGood Working Positions

To understand the best way to set up aTo understand the best way to set up acomputer workstation, it is helpful to understandcomputer workstation, it is helpful to understandthe concept of neutral body positioning.the concept of neutral body positioning.

This is a comfortable working posture in whichThis is a comfortable working posture in which

your joints are naturally aligned. Working withyour joints are naturally aligned. Working withthe body in a neutral position reduces stress andthe body in a neutral position reduces stress andstrain on the muscles, tendons, and skeletalstrain on the muscles, tendons, and skeletalsystem and reduces your risk of developing asystem and reduces your risk of developing a

musculoskeletal disorder (MSD).musculoskeletal disorder (MSD).

The following are important considerations whenThe following are important considerations whenattempting to maintain neutral body posturesattempting to maintain neutral body postureswhile working at the computer workstation.while working at the computer workstation.


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HandsHands,, wristswrists, and, and forearmsforearms are straight,are straight,in-line and roughly parallel to the floor.in-line and roughly parallel to the floor.

HeadHead is level, or bent slightly forward,is level, or bent slightly forward,

forward facing, and balanced. Generally itforward facing, and balanced. Generally itis in-line with theis in-line with the torsotorso..

ShouldersShoulders are relaxed andare relaxed and upper armsupper arms

hang normally at the side of the body.hang normally at the side of the body.ElbowsElbows stay in close to the body and arestay in close to the body and arebent between 90 and 120 degrees.bent between 90 and 120 degrees.


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FeetFeet are fully supported by floor or footrest.are fully supported by floor or footrest.

BackBack is fully supported with appropriate lumbaris fully supported with appropriate lumbar

support when sitting vertical or leaning backsupport when sitting vertical or leaning back

slightly.slightly.

ThighsThighs andand hipships are supported by a well-are supported by a well-

padded seat and generally parallel to the floor.padded seat and generally parallel to the floor.

KneesKnees are about the same height as the hipsare about the same height as the hipswith thewith the feetfeet slightly forward.slightly forward.


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Regard less of how good yourRegard less of how good your

working posture is, working in theworking posture is, working in thesame posture or sitting still forsame posture or sitting still for

prolonged periods is not healthy.prolonged periods is not healthy.


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You should change your working positionYou should change your working position

frequently throughout the day in the followingfrequently throughout the day in the following

ways:ways:

Make small adjustments to your chair orMake small adjustments to your chair or

backrest.backrest.

Stretch your fingers, hands, arms, and torso.Stretch your fingers, hands, arms, and torso.Stand up and walk around for a few minutesStand up and walk around for a few minutes

periodically.periodically.


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These fourThese fourreference posturesreference postures areare

examples of body posture changes that allexamples of body posture changes that all

provide neutral positioning for the body.provide neutral positioning for the body.


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Reclined sitting postureReclined sitting posture. The user's. The user's

torso and neck are straight and reclinetorso and neck are straight and recline

between 105 and 120 degrees from thebetween 105 and 120 degrees from the

thighs.thighs.


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Semi-sittingSemi-sitting

The major advantage of semi sitting is thatThe major advantage of semi sitting is thatthe trunk is mobile particularly if there isthe trunk is mobile particularly if there isno backrest.no backrest.

It is suitable to relieve the worker fromIt is suitable to relieve the worker fromcontinuous standingcontinuous standing


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There is NO one HealthyThere is NO one Healthy

PosturePosture


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Adjusted WorkstationAdjusted Workstation

Important Criteria:Important Criteria:

ArmArm

BackrestBackrest

PosturePostureDeskDesk

TelephoneTelephone

Document HolderDocument Holder

ScreenScreenKeyboardKeyboard

Avoiding Eye StrainAvoiding Eye Strain


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DESIGN OF VDTDESIGN OF VDT

WORKSTATIONWORKSTATION

Visual workspaceVisual workspace

We alter our direction of gaze by movingWe alter our direction of gaze by movingour eyeballs within their sockets and byour eyeballs within their sockets and by

moving our head. It is good to have somemoving our head. It is good to have some

movement of the head during work inmovement of the head during work in

order not to tire the neck muscles.order not to tire the neck muscles.


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The head is supported by the effort of theThe head is supported by the effort of the

muscles in the neck. If you hold your headmuscles in the neck. If you hold your head

still, you muscles are doingstill, you muscles are doing staticstaticwork,work,

that is, they are working continuously withthat is, they are working continuously withno breaks to rest. This is more tiring than ifno breaks to rest. This is more tiring than if

you move your head, when the musclesyou move your head, when the muscles

are doingare doing dynamicdynamicwork, and muscleswork, and musclesgroups get a chance to rest as others takegroups get a chance to rest as others take

over.over.


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Therefore, the visual aspects of theTherefore, the visual aspects of theworkplace should be arranged to causeworkplace should be arranged to cause

the lowest level of static work by the neckthe lowest level of static work by the neck

muscles.muscles.


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You should aim to position frequentlyYou should aim to position frequently

viewed items within a comfortable zone inviewed items within a comfortable zone in

front of you. This is normally within 15front of you. This is normally within 15

above, or 30 below, the horizontal, andabove, or 30 below, the horizontal, and15 to the left and right. In the normal,15 to the left and right. In the normal,

relaxed position of the head, neck andrelaxed position of the head, neck and

eyes, the line of sight is about 10 to 15eyes, the line of sight is about 10 to 15below the horizontal, therefore, viewingbelow the horizontal, therefore, viewing

horizontally straight ahead actuallyhorizontally straight ahead actually

requires a small amount of effort.requires a small amount of effort.


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Distance is also a factor in visual fatigue.Distance is also a factor in visual fatigue.

Visual displays are comfortably viewedVisual displays are comfortably viewed

from 500-750mm or more, depending onfrom 500-750mm or more, depending on

the size of the display components. Thethe size of the display components. Thelens of the eye stiffens as people getlens of the eye stiffens as people get

older, altering the distance at which theyolder, altering the distance at which they

can easily focus, so objects need to becan easily focus, so objects need to bepositioned further away for clear viewing.positioned further away for clear viewing.

They also take longer to focus on things (itThey also take longer to focus on things (it

will happen to you one day!).will happen to you one day!).


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ExerciseExercise

Choose the best office (computerChoose the best office (computer

workstation) lighting arrangements.workstation) lighting arrangements.

Can you detect visibility problems that canCan you detect visibility problems that can

be generated by imperfect lamp positions.be generated by imperfect lamp positions.


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Figure 2Figure 2


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Figure 3Figure 3


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Figure 4Figure 4

ergonomics - office workstation computer) ug- 2007

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