1. Ergonomic
modification for a
person with a desk
job
Dr. Joe Antony
MD ( Physical Medicine and
Rehabilitation)
KGMU, Lucknow.India

2. Contents
2
• Introduction
• Epidemiology
• Benefits of ergonomic modifications
• Biomechanical properties of sitting
posture
• Desired posture for desk job
• Specific ergonomic modifications
for desk job
Ergonomic
modification
for a person
with a desk
job

3. Introduction
• Ergonomics is the science of making the workstation fit,
comfortable, safe, secure, and efficient for the workers to
enjoy giving more productive output to their organization.
• Purpose of ergonomics is to “fit task to the individual” and
not “individual to the task”.
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Dr Joe Antony

4. Epidemiology
• It was estimated that about 40.7 % of the global population was surfing the computers in the year 2012
as compared to 2006 of only 26.2%. [1]
• Marshall et al study reveal that on average, six out of 10 employees used a chair at work and the
number was expected to grow.[2]
• Many researchers report that working 5.41 hours sitting at desk and 7 hour sleeping at night had a great
impact on the physical and mental health.[2]
• Sitting on a chair is one of the most common positions adopted by humans.
• children and adults spend approx. 55% of their working hours or 7.7 hours/day in sitting
postures.[2]
• The ergonomic fit workstations have become a standard practice in various developed countries
1. Acc to the key 2006-2013 ICT data for the world in the year 2013
2.Bureau of Labor Statistics, U.S. Department of Labor. The Economics Daily. Standing or walking versus sitting on the job In 2016. [Internet]. 2017[updated
2017 march 1] Availaible from https://www.bls.gov/opub/ted/2017/standing-or-walking-versus-sitting-on-the-job-in-2016.htm.
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Dr Joe Antony

5. Benefits of ergonomic modifications
1. Decrease Injury risk.
2. Increased Productivity
3. Healthier vision and joints
4. Reduce tension, headaches
5. Improved job satisfaction, work quality and improved morale of workers.
Occupational Safety and Health Administration
(OSHA) standards 2016
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Dr Joe Antony

6. Biomechanical properties of sitting posture
• Weight is transferred through
• Pelvis to Chair seat and then to floor,
• Foot directly to floor,
• Forearm load to armrest and then to floor.
• Back and pelvis to backrest and then to floor
• Workers adopt a posture according to their ease and habits such as slouching, crossing legs, etc.
• These habits increases chances of many work-related musculoskeletal disorders
Moon HH: The effect of correction exercise program on primary school students with idiopathic scoliosis. J Sport Leis Stud, 2007, 31:
1033–1041.
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Dr Joe Antony

7. • Prolonged sitting is a major cause of increased intradiscal pressure and use of lumbar support helps in
preventing aggravated lumbar lordosis.
• Types of posture in sitting
• Forward posture- hip is in lesser than 90 degrees in which COG lies in front of the Ischial
tuberosity and floor supports more than 25% of body weight with increase disc pressure.
• Upright posture - trunk is upright & COG lies above the Ischial tuberosity and floor supports 25%
of body weight.
• Reclined posture - The posture of 100 degrees & above with COG lies behind the Ischial
tuberosity and floor supports less than 25% of body weight. This posture reduces pressure on the
disc.
Dubey N, Dubey G, Tripathi H, Naqvi ZA. Ergonomics for desk job workers-an overview. Int J
Health Sci Res. 2019;9(7):257-66. 7

8. Braddoms textbook of physical medicine and rehabilitation,21st edition 8
Comparative pressure on 3rd lumbar IV disc

9. 9
Desired
posture for
a desk job
Facing forward and not looking up, down, or to either side
Keep elbows bent between 90 and 100 degrees (right
angle),
keep them close to your body, and supported if
possible.
Wrists in neutral position. No
flex, ext or deviation.
Knees approximately 90
degrees with enough space
between
the back of your knees and the
chair to place a fist
Feets - Resting flat on the
floor or supported by a
footrest.
Hips- Bent around 90 degrees with your thighs parallel to
the floor
Low back- Supported to maintain its
natural curve
Shoulders- Relaxed (not slouched or raised).
Office Ergonomics Handbook,Fifth edition,2008,Govt of Ontario

10. Ergonomic modification for a person with a
desk job
10
1. Chair
2. Workstation
• Desk
• Computer
• Keyboard and mouse
• Monitor
• Laptop
3. Office lighting
4. Rest breaks
5. Office arrangement
6. Environmental concerns

11. Chair
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Dr Joe Antony

12. Chair
• Chair is the most important part of office workstation.
• Chair has to fit the worker and suit tasks worker do.
• An ‘Average chair’ is designed for males of 5’10’’
• So , same chair won’t fit every employee
• A chair can be called ‘ergonomic’ only if it is adjustable
• There should be a trial period of about 4 weeks for employees to select the desired chair and adjustments.
Office Ergonomics Handbook,Fifth edition,2008,Govt of Ontario 12
Dr Joe Antony

13. General features of
an ergonomic chair
Office Ergonomics Handbook,Fifth edition,2008,Govt of Ontario
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1. 5-caster swivel base
2. Armrests
3. Height adjustable seat pan
4. Tilt adjustable back rest
5. Ability to make adjustments easily
while sitting in the chair
6. Firm padding covered with non-
slip, breathable fabric

14. Specific features of an ergonomic chair
Seat Pan
• Rounded front edge
• Wide and deep (long)
enough to fit you
comfortably
• Adjustable in angle
Back Rest
• Padding for the low back
area that is curved to fit the
shape of your back
• Height adjustable (separate
from seat pan)
• Adjustable angle with
locking mechanism
• Wide and high enough to
fit your back comfortably
Office Ergonomics Handbook,Fifth edition,2008,Govt of Ontario
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Arm Rest
• Ability to rest the arms as
they hang freely by your
side.
• Should provide height and
width adjustability.
• Should not interfere with
the work surface.

15. Lumbar support
• In sitting posture lumbar spine tends to lose some of its natural curvature.
• An effective lumbar support of a chair is designed to help maintain the natural curvature of the spine when sitting.
• If you are feeling pain while sitting, the lumbar support of your chair may not be placed correctly.
Office Ergonomics Handbook,Fifth edition,2008,Govt of Ontario 15
Dr Joe Antony

16. Chair Height
If Keyboard is on adjustable platform
• Lower the seat pan so feet rest comfortably
on the floor.
• Check for pressure points. Even pressure
should be felt from the seat pan.
• More pressure is felt near the back of the
seat (buttock region), raise the chair.
• More pressure is felt under the thighs (near
the knees), lower the chair
If Keyboard is on fixed platform
• Adjust chair height so employee can type
comfortably with neutral wrist and arm
positions.
• Use a footrest if feet do not rest flat on the
floor after height of chair is adjusted
Office Ergonomics Handbook,Fifth edition,2008,Govt of Ontario
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17. Work station
17

18. Workstation
Adjustable desks
• A complete workstation that
allows for both regular desk
work and space for the
computer.
• Computer section should have
an adjustable portion for the
keyboard and mouse and a
separate adjustable portion for
the monitor.
• Portion designed for the
keyboard should have enough
space for the mouse and
keyboard to be placed side by
side.
Non-adjustable desk
• Raise the desk using stable
support (ie. blocks under
desk legs) until work
surface or keyboard is at
elbow height.
Adding adjustability
• Add attachments to your
desk such as keyboard tray
or monitor arm.
• Use a smaller separate
computer workstation and
continue to use your desk
for regular work.
• L-shaped workstation that
allows for a separate
writing and typing area.
Office Ergonomics Handbook,Fifth edition,2008,Govt of Ontario 18
Dr Joe Antony

19. Telephone usage
• If employee have to write or type while
talking on the phone, he should be
provided a headset or speakerphone to
keep hands free.
• This will help to reduce awkward neck
and shoulder positions.
Office Ergonomics Handbook,Fifth edition,2008,Govt of Ontario 19
Dr Joe Antony

20. Keyboard
Adjustable keyboard arm
• Move the keyboard and
mouse to elbow level.
Non Adjustable keyboard
arm
• Adjust the height of chair
so the keyboard and
mouse are at
approximately elbow level
Office Ergonomics Handbook,Fifth edition,2008,Govt of
Ontario
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Ergonomic Key Board
Dr Joe Antony

21. Key board trays
• Allow enough room for both the keyboard and mouse.
• Be easily adjustable in both height and angle (in all directions).
• Be free of attachments under the tray that can cause bruising, scrapes or contact pressure with your
thighs or knees.
• Be easily moved under the desk and out of the way.
• Allow enough space for a wrist rest if desired.
Office Ergonomics Handbook,Fifth edition,2008,Govt of Ontario 21
Dr Joe Antony

22. Mouse
• Mouse pad should be used in order to keep the mouse clean and moving easily.
• Even users who have an optical mouse should use a mouse pad as it provides the best surface for the movement of
the mouse and for the optical sensor to detect movement.
• To reduce stress on your dominant mousing hand try to use the mouse with opposite hand, provided that you are
using a universal design mouse.
• Alternating mousing hands can serve to reduce stress placed upon a particular arm while also improving working
posture in some instances.
Office Ergonomics Handbook,Fifth edition,2008,Govt of
Ontario
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23. Monitor
• Monitor and keyboard should be directly in front of you.
• Top of the monitor should be at eye level.
• Monitor should be at least one arm’s length away from you.
• Monitor should be angled slightly up towards your eyes.
• Angling the Monitor up too high can increase glare
• LCD monitors are better for eyes than other types of monitors
Office Ergonomics Handbook,Fifth edition,2008,Govt of Ontario 23
Dr Joe Antony

24. Recommendations for use of Laptop
• Use a computer docking station when in the office.
• Consists of a full size monitor, keyboard, and mouse with the laptop basically serving as the hard
drive.
• An alternative option - use the laptop’s screen and simply connect an external full-sized keyboard.
• Adjust the viewing height and distance the same way you would adjust a regular monitor.
• External full-sized keyboard would also need to be correctly positioned as discussed in a previous
section.
• When on the road, pack a light-weight keyboard and mouse
Office Ergonomics Handbook,Fifth edition,2008,Govt of
Ontario
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Dr Joe Antony

25. Office Lighting
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Dr Joe Antony

26. Office lighting
• Improper lighting can lead to eye strain and awkward postures.
• If light levels are too low, muscles of eyes can be strained and workers may adopt awkward postures to
compensate.
• Since computer and paperwork are commonly performed at same time, light levels must suit both types
of work.
• A desk lamp may be useful to control light levels as needed.
• Glare is a common problem with lighting in offices.
• It makes it difficult to see computer screen and strains the eyes. There are two forms of glare
◆ Direct glare occurs when light shines directly in your eyes.
◆ Indirect glare occurs when light is reflected from a surface. For example, light which may hit
monitor and reflect into your eyes.
Office Ergonomics Handbook,Fifth edition,2008,Govt of
Ontario
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Dr Joe Antony

27. Techniques to avoid glare
• Position your monitor perpendicular to the windows and between overhead light panels.
• Use curtains and blinds to control the amount of natural light.
• Eliminate light sources that shine directly into your eyes.
• Eliminate light sources that reflect into your eyes.
• Consider the use of LCD(flat panel) monitors.
• Dim overhead lights.
• Angle the monitor away from the light.
• Place filters or fixtures on overhead lights.
• Tint windows.
• Cover the monitor with an anti-glare screen.
Office Ergonomics Handbook,Fifth edition,2008,Govt of
Ontario
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Dr Joe Antony

28. Rest breaks
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29. Rest breaks
• If computer workstation can be adjusted, one option is to stand while working at computer.
• Even if workstation is not fully adjustable, tasks like talking on the phone, can be done while standing.
• It is preferable to break up sitting and standing tasks throughout the day.
• Other daily tasks, such as filing and interacting with other staff can be done when away from desk.
• Avoid remaining seated for extended periods of time.
• Train employees to stand up and change position every hour.
Office Ergonomics Handbook,Fifth edition,2008,Govt of Ontario 29
Dr Joe Antony

30. Environmental concerns
Air quality, Thermal comfort, Noise
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Dr Joe Antony

31. Air Quality
Common concerns
• Eye, nose and throat
irritations
• Headache
• Dry mucous membranes
• Dry skin
• Mental fatigue, trouble
concentrating
• Nausea and dizziness
• Increased incidence of
respiratory infections
How to identify
• Co-workers have had most
of the symptoms listed
above on a weekly basis.
• Building ventilation
system is deficient.
• Building has musty or
chemical odors and/or has
a history of water leaks
Office Ergonomics Handbook,Fifth edition,2008,Govt of
Ontario
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How to prevent
• Regular maintenance of
the ventilation system and
regular duct cleaning.
• Providing air purifiers in
different areas of the
office.
• Identifying possible
sources of mould, i.e. wet
spots on ceiling tiles
Dr Joe Antony

32. Thermal comfort
• Thermal comfort is affected by,
• Heating, ventilation and air conditioning (HVAC) system,
• Work activities
• Personal preference
• Feeling too cold or too hot has to be addressed
• Recommended temperature- 20 to 23.5C in the winter and 23 to 26C in the summer with a relative
humidity between 30% and 60%.
• Solutions
• Agree on one temperature setting at your work place. Workers can then dress according to their
personal preference.
• Dress in layers if temperatures fluctuate.
• As a temporary solution, investigate use of heaters or fans to accommodate personal preferences.
Office Ergonomics Handbook,Fifth edition,2008,Govt of
Ontario
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Dr Joe Antony

33. Noise
• Noise is any unpleasant sound.
• Concerns with noise
• Interfere with communication.
• Annoy or distract people nearby.
• Increase the level of concentration required.
• Increase the level of fatigue.
• Cause stress
• Sources of noise in an office environment are,
• Co-workers,
• Ventilation systems,
• Fans,
• Computers,
• Photocopiers,
• Telephones,
• Everyday outdoor noises, such as traffic.
Office Ergonomics Handbook,Fifth edition,2008,Govt of
Ontario
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Dr Joe Antony

34. • Noise reduction is a specialized field in itself, but several techniques may be used to reduce
noise.
• Sound-absorbing tile, carpet, and barrier walls can be used.
• Noisy equipment can be isolated. For example, place the photocopy machine in a
separate room to reduce noise.
• Temporarily use earplugs while investigating noise reduction methods.
• Follow a regular maintenance schedule for the office equipment.
Office Ergonomics Handbook,Fifth edition,2008,Govt of
Ontario
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Dr Joe Antony

35. References
• Bureau of Labor Statistics, U.S. Department of Labor. The Economics Daily.
Standing or walking versus sitting on the job In 2016. [Internet].
2017[updated 2017 march 1] Availaible from
https://www.bls.gov/opub/ted/2017/standing-or-walking-versus-sitting-on-
the-job-in-2016.htm.
• Occupational Safety and Health Administration (OSHA) standards
• Moon HH: The effect of correction exercise program on primary school
students with idiopathic scoliosis. J Sport Leis Stud, 2007, 31: 1033–1041.
• Office Ergonomics Handbook,Fifth edition,2008,Govt of Ontario
• Dubey N, Dubey G, Tripathi H, Naqvi ZA. Ergonomics for desk job
workers-an overview. Int J Health Sci Res. 2019;9(7):257-66.
• International handbook of occupational therapy interventions
• Braddoms textbook of physical medicine and rehabilitation,21st edition
Thank
you
Dr Joe Antony