Z Score,T Score, Percential Rank and Box Plot Graph
MUSCULOSKELETAL PROBLEMS IN SITTING & STANDING
1. MUSCULOSKELETAL PROBLEMS IN SITTING & STANDING
Presented by ,
Jinson Jose
S1 M Tech
IE& M
Roll No:4
mail me @
geothomasseril@gmail.com
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2. 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
3. CONTENTS cont…
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• 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
4. 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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6. 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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10. Static work: Design for standing and
seated 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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11. 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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12. Some Advantages Of The Standing Work
Position cont…..
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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
13. 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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14. 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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15. 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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16. 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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17. 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 17
19. 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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20. 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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21. 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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22. Design for standing workers
As 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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23. Evaluation of standing aids
Several researchers have investigated the effects of standing aids on
comfort and
fatigue 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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24. Evaluation of standing aids
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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
25. Standing aids cont…
Compression stockings -
• The wearing of compression
stockings bought about a
significant reduction in leg
swelling
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27. Sit – stand production line
• Sit–stand
industrial production line. Note
the use of height adjustable sit–
stand stools and a
large sloping footrest to
accommodate a variety of trunk–
thigh angles. 27
28. 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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29. • Tilted work surfaces
can be effective when
used with both
conventional and
alternative seats.
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Work Surface Design
32. Work station cont…
Standard Way
• Adjustable workstation
• Adjustable chair
• Foot rests
• Adjustable monitor
• Document holder
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33. 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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34. • 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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35. • Awkward positions
Bent or curved handles
Extensions or add-ons
Headphones
Support equipment overhead
Step stool
• Forceful exertions
Soft-touch keyboards/buttons
Lifting devices
Tools cont…
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37. 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 wheels37
38. 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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42. CONCLUSION
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• 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
43. REFERENCE
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• R.S Bridger , “introduction to ergonomics” : 2000-2014 ;
edition
• Steven Weigle , OSHA academy – course 711 study guide ;
ergonomics & WSDs
•https://www.wikipedia.com
