MUSCULOSKELETAL PROBLEMS IN SITTING & STANDING

Presented by ,Jinson JoseS1 M Tech

IE& MRoll No:4

mail me @ geothomasseril@gmail.com 1

CONTENTS

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• Definition – work related MSDs• Most important localization of WMSDs• MSDs & Ergonomics • Causes of MSDs• Formula to prevent MSDs• Design for sitting & standing workers• Advantages of standing work• Behavior characteristics of unconstrained standing• For standing workers• Transformation from standing to sitting• Sitting postures• Perfect sitting posture• Spinal problem in standing• Spinal problem in sitting

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CONTENTS cont…• Design for standing workers • Evaluation of standing aids• Sit – Stand production line• Work surface design• Ergonomic approach to reduce MSDs• Work station• Tools• certain unhealthy postures causing MSDs• Conclusion• Reference

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Definition - Work Related Musculoskeletal Disorders (MSDs)

• The term musculoskeletal disorders denotes the health problems of locomotor apparatus i.e of:

• Muscles – tissues that contract to make movements

• Tendons – tissues that connect muscles to bones

• Skeleton - load bearing structure

• Cartilage – tissues that provides cushioning & reduce friction b/w bones

• Ligaments – tissues that connect bones to bones

• Nerves – communication s/m that links muscles, tendons & other tissues to brain

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Most Important Localization Of Work-related Musculoskeletal Disorders (MSDs)

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MSDs & ERGONOMICS

• MSDs are often confused with ergonomics

• Ergonomics is the science of fitting work place conditions & job demands to the capabilities of workers

• In other words MSDs are the problem & ergonomics is the solution

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Causes of MSDs

• Awkward postures

• vibrations

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Causes of MSDs cont….

Forceful Excertions

Repetitive Motions

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Formula to prevent MSD

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Static work: Design for standing andseated workers

• Humans are designed to stand on two legs, but they are not designed to stand still.

• Standing is the position of choice for many tasks in industry but it can lead to

•Discomfort if insufficient rest is provided or if unnecessary postural load is placed on the body.

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Some Advantages Of The Standing Work Position

1. Reach is greater in standing than in sitting.

2. Body weight can be used to exert forces.

3. Standing workers require less leg room than seated workers.

4. The legs are very effective at damping vibration.

5. Lumbar disc pressures are lower

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Some Advantages Of The Standing Work Position cont…..

6. It can be maintained with little muscular activity and requires no attention

7. Trunk muscle power is twice as large in standing than in semi-standing or sitting

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Some Behaviour Characteristic Of Unconstrained Standing

1. stand still

2. Bear weight on one leg 3. Lean backwards against anything

//4. Use a footrest //5. Sit down when tired

6. Maximise contact with fixed objects

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Some Behaviour Characteristic Of Unconstrained Standing cont…..

7. Rest head on hand

8. Rest one foot on an object

9. Rest knee on something

10 . Rest hands on knees

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For standing workers• Prolonged daily standing is known to be

associated with low back pain.

• Where possible, jobs that require people to stand still for prolonged periods without some

• external form of aid or support must be redesigned to allow more movement or to

• allow the work to be done in a combination of standing and sitting postures.

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Transformation From Standing To Sitting

• Posterior tilting of the pelvis and flattenting of the lumbar curve during the transition

from standing to sitting.

• Much of the postural adaptation to sitting takes place in the back, rather than the legs.

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Sitting Postures

• The lower back is supported by the chair and the fits the curve of the spine.

• The back of the knees are 3-4 inches from the chair, the feet are flat on the floor, the elbows, arms, and wrists are at neutral positions. The monitor is kept at eye level.

• This individual is changing his position (not being static) without comprising the “correct” positions

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Perfect Sitting Posture

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Spinal Problems In Standing

• Low back pain is common in standing workers .

• In extended postures the facet joints may begin to take on some of the compressive load.

• If the lumbar intervertebral discs are degenerated,

• the space between adjacent vertebrae decreases and the load on the facet joints increases even more.

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Spinal problems in sitting

• Sitting has a number of advantages over

standing as a working position

• Static,low-level activity of the soleus and

tibialis anterior muscles is required in

standing and

• these muscles can fatigue.

• Because the lower limbs drain blood against

gravity,

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Spinal Problems In Sitting

• pooling may occur when someone stands still for long periods,

causing swelling at the ankles.

• In extreme circumstances, reduced return of blood to the

heart may cause a drop in blood pressure and the person may

faint

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Design for standing workersAs a rule of thumb, all objects that are to be used by standing workers should be placed between hip and shoulder height to minimise postural stress caused by stopping or working with the hands and arms elevated.Some workspace design faults that increase postural stress in standing workers can be summarised as follows 1. Working with the hands too high and/or too far away:

compensatory lumbar lordosis.2. Work surface too low: trunk flexion and back muscle strain.3. Constrained foot position due to lack of clearance: worker stands

too far away.4. Working at the corner of the bench: constrained foot position,

toes turned out too much.

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Evaluation of standing aids

Several researchers have investigated the effects of standing aids on comfort andfatigue in standing.

Footrests And Footrails - The footrest raised the resting foot 250 mm above the level of the floor and resulted in a net posterior rotation of the pelvis of 4–6 Degrees

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Evaluation of standing aids

Anti-fatigue Mats - Mats do not seem to reduce lower leg fatigue although they do reduce discomfort in the lower leg, feet and muscle fatigue in the erector spinae Muscles

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Standing aids cont…

Compression stockings -

• The wearing of compression

stockings bought about a

significant reduction in leg

swelling

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Standing Aids Cont…

Toe Space Panels

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Sit – stand production line

• Sit–standindustrial production line. Note the use of height adjustable sit–stand stools and alarge sloping footrest to accommodate a variety of trunk–thigh angles.

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Work Surface Design

• Workstations can be further improved by considering various aspects of desk and bench design.

• Some important considerations are the provision of tilt in the work surface and/or of document holders and the provision of free space in the working area

• Several studies have indicated that tilted desktops (of 15 or even 10 degrees) do reduce the trunk and neck flexion of seated persons engaged in reading and writing and thus reduce the load on the corresponding parts of the spine

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• Tilted work surfaces can be effective when used with both conventional and alternative seats.

Work Surface Design

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Ergonomic approach for reducing MSDs

• Workstations

• Tools/equipment

• Facilities

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Work stations

The objective is to:

• Fit the workstation to the employee

• Reduce awkward positions

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Work station cont…

Standard Way

• Adjustable workstation

• Adjustable chair

• Foot rests

• Adjustable monitor

• Document holder

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Fully adjustable workstation,

• table height fully adjustable which adjust the height of the monitor, the keyboard adjusts from level to 45 degrees

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• Use of Force or of grip-strength Longer/shorter and

thicker/thinner handles• Repetitive motion• Ratcheting mechanism or

gears• Power tools

Electric stapler Electric knife Spring-loaded returns

Tools

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• Awkward positionsBent or curved handlesExtensions or add-onsHeadphonesSupport equipment overheadStep stool

• Forceful exertionsSoft-touch keyboards/buttonsLifting devices

Tools cont…

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Certain Unhealthy Postures Causing MSDs

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What’s wrong with this. If person continually performs this activity of filing overhead could become a problem. What if person was not standing on cart? Would overhead reach be longer? Also notice that the proper piece of equipment is not being. This has wheels

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This step stool enables the person to reach the level she needs more comfortably. Also notice is proper type. Becomes immobile when step on.

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Keyboard too low. Hands and wrists in praying mantis position.

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What’s wrong. Back not supported by the chair completely, leaning forward. Good- feet are flat on the floor.

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Legs crossed, feet not on floor, back not properly supported.

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CONCLUSION

• Musculoskeletal problems in sitting & standing mainly

arises when there is unhealthy ergonomics

• Ergonomics is the solution for all those MSDs

• proper awareness for sitting & standing workers &

providing them perfect

• workstations

• Tools &equipments

• Facilities reduce MSDs

• As a whole these changes reflect by increasing the

productivity of the firm

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REFERENCE

• R.S Bridger , “introduction to ergonomics” : 2000-2014 ; edition

• Steven Weigle , OSHA academy – course 711 study guide ; ergonomics & WSDs

•https://www.wikipedia.com