Transcript What is Ergonomics? - Southern Methodist University

Preventing Musculoskeletal
Illnesses through Ergonomics
Session Objectives
ERGONOMICS
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Define ergonomics and provide brief history
SMU Statistics
Discuss purpose, scope and goal of ergonomics
Design and Task Factors that effect ergonomics
Physical effects of risk factors
Present application strategies with emphasis on job
design
Examples
What Is Ergonomics?
ERGONOMICS
 Ergonomics focuses on fitting jobs and tasks to the
worker that must perform them.
 The basic definition is “the study of work in relation to the
physiological and psychological capabilities and limitations
of people.”
 Ergonomics utilizes the principles of many different
disciplines, engineering, physics, psychology, human
physiology, and business management.
 Ergonomists are able to reach their goals through
engineering and workplace designs.
Ergonomics from the Greek words:
 Ergo = work
 Nomos = laws
Other Terms
ERGONOMICS
Engineering psychology
 Human factors
 Human engineering
 Biomechanics
 Work physiology
 Engineering anthropometry
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History of Ergonomics
Stover H. Snook Ph.D., Harvard School of Public Health
ERGONOMICS
PHYSIOLOGICAL ROOT
• Ramazzini (1633-1714)
• Alice Hamilton (1869-1970)
• Health of Munnition Workers Committee (1915)--UK
• Industrial Fatigue Research Board (1918)--UK
• Industrial Health Research Board (1928)--UK
• Harvard Fatigue Laboratory (1927-1946)
ANTHROPOMETRIC ROOT
• WWI--Army surveys for clothing size
• U.S.. Depts. of Agriculture and
Commerce (1939) Surveys of women
and children, and standards in clothing
sizes
• WWII--Military surveys for clothing
and equipment
PSYCHOLOGICAL ROOT
ERGONOMICS
• Hawthorne Studies (1924-1927 NRC)
• WWII weapons systems
• Army gunnery studies (Tufts University)
• Navy systems Research Lab (Harvard, Johns
Hopkins)
• Air Corps flight program (Ohio State)
ENGINEERING ROOT
• Frederick W. Taylor (1856-1915)--time study
• Frank and Lillian Gilbreth--motion study
• WWII radar, computers, nuclear devices, high performance aircraft
• Biomechanics--medical applications
Top Five Accident Types (4/1/00 to 3/31/03)
946 Claims
0.34
0.35
Accidents per $1MM of Payroll
0.30
761 Claims
0.27
0.25
0.20
422 Claims
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454 Claims
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20 Claims
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207 Claims
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187 Claims
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17 Cliams
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11 Claims
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10 Claims
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21 Claims
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7 Claims
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MMH
SLIPS/FALLS-SAME
LEVEL
STRUCK BY/AGAINST
Southern Methodist Univ.
CTD
SLIPS/FALLSELEVATION
Liberty Mutual Industry Average
ALL OTHER
Top Five Accident Types (4/1/00 to 3/31/03)
$0.10
$2,647,073 Incurred Cost
$0.09
$0.09
$2,154,909 Incurred Cost
$0.08
Dollar Cost per $100 of Payroll
$0.08
$0.07
$1,430,654 Incurred Cost
$0.05
$0.06
$1,243,551 Incurred Cost
$0.04
$145,245 Incurred Cost
$0.04
$0.05
$0.04
$0.03
727,487 Incurred Cost
$0.03
$73,570 Incurred Cost
$0.02
$0.02
$27,975 Incurred Cost
$0.01
$752,770 Incurred Cost
$0.03
$66,760 Incurred Cost
$0.02
$45,747 Incurred Cost
$0.01
$24,781 Incurred Cost
$0.01
$0.01
$0.00
MMH
SLIPS/FALLSSAME LEVEL
STRUCK
BY/AGAINST
Southern Methodist Univ.
CTD
SLIPS/FALLSELEVATION
Liberty Mutual Industry Average
ALL OTHER
Ergonomics
ERGONOMICS
The overall goals of ergonomics are:
 Provide a safe and healthful work environment
engineered to the capabilities of the human
body
Improved Work Methods
Increased Efficiency
Better Tools
Decrease worker fatigue and discomfort through
the elimination or minimization of excess effort
Increase efficiency and productivity
Less Fatigue
Fewer Errors
Less Rework
Improve production by providing designs that
reduce the potential for human error
Enhance customer service through improved
worker morale
Elevate job satisfaction
Reduce injuries/illnesses
Reduce Costs
Increased Productivity
Anthropometry
ERGONOMICS
The average person fallacy
Individual Differences:
Most Important Are Age and Gender
ERGONOMICS
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We get shorter as we age
We get weaker as we age
Women have less than 50% of the isometric strength as
men
Female heart rates are higher
Females recover faster from exertions
8% of males are color deficient
Response time, vision, and hearing deteriorate with age
10% of population is left handed
Material
Characteristics
Task/Workplace
Characteristics
Task Demands
Organizational
Characteristics
Environmental
Characteristics
Personal
Characteristics
Physiological
Capacity
Primary factors
influencing task
demands to worker
capacity
(dempsey, 1998)
Quality
Performance
Fatigue
Discomfort
Injury
Worker Capacity
Psychological
Capacity
Biomechanical
Capacity
P.G. Dempsey, A Critical review of biomechanical, epidemiological, physiological and
psychophysical criteria for designing manual handling tasks, Ergonomics, 1998, Vol. 41. No
1
Ergonomics Process
ERGONOMICS
Pre - Injury Prevention
Management Leadership
Targeting Primary Cost Drivers
Ergonomic Job Accommodations
Job Hazard Analysis
Transitional Duty
Worker
Health Care Liaison Plan
Rehabilitation Services
Disability Management Programs
Hazard Reduction & Control
Education and Training
Employee Participation
Job Placement Medical Evaluations
Post - Injury Action and Return to Work
Shoulder/Neck/Back
ERGONOMICS
The shoulder joint is perhaps one of the most mobile and most
complex of the joints in the human body. The importance of the
shoulder joint becomes apparent when one considers the types of
activities associated with the shoulder:
• Pushing
• Pulling
• Lifting
• Pressing
• Holding
The shoulder joint is involved either as a prime mover or as a support
for almost every activity that involves the arms. This is accomplished
by the inherent mobility of the shoulder. The shoulder is made up of
complex bones and muscles that interact to form the “shoulder
girdle.”
Shoulder/Neck/Back
ERGONOMICS
There are several bones involved in
the shoulder joint. These bones
Include:
Scapula
Humerus
Clavicle
Acromion
Coracoid Process
Several of these bones have laymen’s terms by which they are
known, including “shoulder blade” for scapula, “upper arm” for
the humerus, and “collar bone” for the clavicle.
Shoulder/Neck/Back
ERGONOMICS
The vertebrae are the bone components of the back, and collectively
Form the spine. The vertebrae are classified based on their location
In the spine, including:
 Cervical
 Thoracic
 Lumbar
 Sacrum
 Coccygeal
Shoulder/Neck/Back
ERGONOMICS
Each vertebra of the spine is separated from its neighboring vertebrae
by the intervertebral discs. The discs provide cushioning between the
vertebrae and allow for some degree of mobility, which enables the
vertebrae to twist and bend in relation to one another.
The overall structure of the discs and vertebrae
is held together by ligaments, and moved
through the action of muscles. The muscles
also provide stability to the torso and allow for
posturing of the back.
The vertebrae themselves offer protection to the
spinal cord, which passes between vertebrae via
the foramen. Foramen is the space between vertebrae.
CTDs
ERGONOMICS
Cumulative Trauma Disorders:
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To start with, CTDs are disorders of the musculoskeletal
system. That means that they are related to the muscles,
nerves, tendons, ligaments, cartilage, and joints of the body.
Typically, CTDs are not sudden injuries, but are rather
illnesses that develop gradually over time.
CTDs are commonly a resultant of repeated mechanical
stresses on the body.
CTDs can result in losses of mobility and strength of the body.
CTDs are also commonly known as Work-Related
Musculoskeletal Disorders, which means that the person’s
occupation played a role in development of the condition, or
made a preexisting condition worse.
Common CTD Symptoms
ERGONOMICS
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Loss of feeling, sluggish
or weak muscle or joint
Numbness
Tingling
Soreness in evenings
or after extended
activity periods
Hand/Wrist/Arm
ERGONOMICS
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Common ergonomic risk factors to the hand/wrist/arm include:
 Awkward
Postures
 Forceful Exertions
 Repetitive Movements
 Mechanical Stress
 Vibration
 Temperature Extremes
Wrist Flexion
Ulnar Deviation
Wrist Extension
Radial Deviation
Hand/Wrist/Arm
ERGONOMICS
The nerves that service the forearm and hand include the ulnar,
radial, and musculocutaneous nerves. The nerves that connect and
move the wrist and hand include the radial, ulnar, and median nerves.
The ulnar nerve and arteries travel along the forearm and outside the
carpal tunnel. The median nerve passes through the carpal tunnel.
Hand/Wrist/Arm
ERGONOMICS
The hand/arm/wrist are subjected to several different stresses.
Therefore, there are quite a few CTDs associated with the
hand/arm/wrist. These include:
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Tendonitis
 Tenosynovitis
De Quervain’s Disease
Trigger Finger
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Carpal Tunnel Syndrome (CTS)
 Ganglion Cysts
 Epicondylitis
Hand/Wrist/Arm
ERGONOMICS
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Tendonitis
Inflammation of tendons.
Tendons are the connective
tissue that links muscles to
bones, and allows for translation
of muscular contraction into
skeletal movement. Undue
physical force and repetitive
motions can cause inflammation
of the tendons, resulting in
tendonitis.
Hand/Wrist/Arm
ERGONOMICS
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Tenosynovitis (De Quervain’s Disease, Trigger Finger)
Inflammation of a tendon sheath. Tendon sheath provide
lubricated pathways in the human body so tendons can move
freely along their designed axis of movement. The sheath
minimizes friction which helps to protect the tendon. Repetitive
motion can cause inflammation of these sheaths.
Hand/Wrist/Arm
ERGONOMICS
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Carpal Tunnel Syndrome - CTS
Compression of the median nerve within
the carpal tunnel. The carpal tunnel is a
location where several tendons pass
through the wrist, connecting to the
fingers of the hand. The median nerve
also passes through the carpal tunnel.
When pressure in the carpal tunnel is
increased (possibly due to ergonomic
risk factors) that pressure is translated to
the median nerve, causing inflammation
to the nerve. This can result in symptoms
of numbness, tingling or burning in the
area of the hand connected by the
median nerve (first 3 fingers)
Hand/Wrist/Arm
ERGONOMICS
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Ganglion Cysts
A benign cystic tumor connected to a
joint membrane or a tendon sheath.
These cysts consist of a thin fibrous
capsule enclosing a clear mucinous
fluid. Most commonly seen on the
backside of the wrist, ganglionic
cysts may also form at the shoulder,
elbow, or knees.
Hand/Wrist/Arm
ERGONOMICS
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Epicondylitis
Inflammation of the tendons that anchor
the muscles of the forearm to the elbow.
These muscles and tendons also connect
to both the fingers and the hand.
Repetitive use of these muscles and
tendons, in maneuvers such as grasping,
twisting, and gripping, can cause
inflammation, and thus epicondylitis.
Other terms by which epicondylitis is
also known are:
Lateral Epicondylitis – Tennis Elbow
 Medial Epicondylitis – Golfer’s Elbow
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Awkward Postures = Postures
outside of neutral.
Neutral is the optimal
position of each joint
that provides the
most strength
and control
Awkward or unsupported
postures that stretch
physical limits, can
compress nerves and
irritate tendons
Before: Technician tilts his
neck forward to view the
screen into a non-neutral
posture. He also bends
over resting on his
forearms to write on the
documents.
Ergonomic Improvement:
Technician easily views
the screen from a neutral
posture. The workstation
adjusts to accommodate
different working heights
and users. When
standing, work should be
about elbow height.
Repetition = Performing the same motion
or group of motions excessively.
Examples of Repetition
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Repeating the same motion every few
seconds or repeating a cycle of motions
involving the same body parts more
than twice per minute for more than 2
consecutive hours in a row
Using a tool or an input device, such as
a keyboard in a steady manner for
more than 4 hours total in a work day
Excessive
repetition of
movements can
irritate tendons
and increase
pressure on
nerves
Force = A strong physical exertion
Exertion = the tension
produced by muscles
and transmitted through
tendons
Excessive muscle tension
can contract muscles to
their maximum capability
which can lead to fatigue
and possible damage to the
muscles and other tissues.
Before: Three
employees
climb on
garbage bin to
dump cart full
of waste. They
risk back strain
and lacerations
while tipping
cart over to
empty it.
Ergonomic
Improvement:
One worker
easily dumps
waste in half
the time.
Applications of Ergonomics
ERGONOMICS
Workplace design
 Product design
 System design
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Control Strategies
ERGONOMICS
Engineering
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The design and layout of the workplace, systems to
be assembled, and the selection of
equipment/accessories.
Work Methods
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How the task is being completed.
Administrative
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Scheduling of work, work habits, case management,
& training.
Administrative Controls
ERGONOMICS
Early Symptom Reporting
 Gradual Break – In
 Job Rotation
 Breaks/Stretching
 Training on Job Tasks
 Case Management of Injuries
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Psychosocial Factors
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Work Environment/Organization
Performance/Time Pressures
Role within Process – Clarity/Ambiguity
Recent Changes in Process/Equipment
Advancement Opportunities
Perceived Workload
Job Satisfaction
Safety Culture
Employee Relationship w/Management
Neutral Posture for Computer Use
ERGONOMICS
Position the monitor about an
arm’s length away directly in
front of you. The top of the
screen no higher than eye
level (Unless the user wears
bi-focal glasses)
Use a document
holder close to the
monitor rather than
laying papers flat
Mouse should be next to
keyboard both at a height
equivalent to the user’s seated
elbow height
Knees comfortably bent with
feet resting on the floor. If the
chair is raised so the keyboard
height equals elbow height, use
a footrest .
Adjust the seat height
so upper arms hang
vertically, elbows bent
about 90 degrees,
shoulders relaxed and
wrists fairly straight
Adjust
the back
rest to
provide
firm
support
to the
small of
the back
Task Breaks and Stretches
ERGONOMICS
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Task breaks are VERY effective in reducing the risk of
CTD
Short recovery periods are beneficial every 30
minutes
Use specific movements to
optimize recovery
Take a deep
breath!
Exhale!
Time Out for Busy Hands
ERGONOMICS
•Spread fingers wide
and hold for 5 counts.
•Grasp palm and
fingers; gently bend
back wrist. Hold 5
counts.
•Rotate wrist in
circular motion.
•Curl fingers into a
fist starting with the
little finger.
Hold
for 5 counts.
•Flex and extend
wrist in waving
motion.
ERGONOMICS
Shoulder/Back Stretches
•Lean back gently with
hands supporting lower
back. Hold for 5
counts. Don’t over
arch.
•Gently roll shoulders
backwards 5 times and
then forward 5 times.
•Move arms overhead
in a climbing motion 10
times.
ERGONOMICS
Neck Stretches
•Gently tilt your
head back as if
you are looking at
the ceiling/sky.
•Gently tilt your
head forward
bringing your chin
towards your
chest.
•Gently tilt your
head from side to
side
FURNITURE AND WORKSTATION ERRORS
ERGONOMICS
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Ergonomic features
that seem to add
value but don’t
 Keyboard height side
surface is too shallow
for a computer.
 Overhead file cabinet
blocks monitor –
forcing an awkward
setup.
FURNITURE AND WORKSTATION ERRORS
ERGONOMICS
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Armrests that get in
the way.
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Too large, too far forward
Keep worker from sitting
close to workstation.
Forces long reach… OR
Workers sit at edge of chair
Here, this worker bought
his own back pad to
compensate for the
problem.
Examples
ERGONOMICS
BEFORE
AFTER
Examples
ERGONOMICS
Examples