1

Addressing the Root Cause of Preventable Injuries

Presented by:  Misty J. Chapman

Ergonomic Consultants of Indiana 11595 N. Meridian Street Suite 140 

Carmel, IN 46032 (317) 708 ‐ 4832www.eci‐in.com

2

Musculoskeletal Disorders in the Workplace

3

Musculoskeletal disorders, or MSDs, are injuries or illnesses to soft body tissue such as:

Muscles

Nerves

Tendons

Ligaments

Joints

Cartilage

Spinal Discs

4

Sprains/Strains Injuries

1. Sprains:

‐ stretching or tearing ligaments

2. Strains:

‐ stretching or tearing tendons or muscles

Chart B. Distribution of sprain, strain, and tear cases requiring days away from work by selected event or

exposure and part of body, all ownerships, 2011

5

Common Musculoskeletal Disorders (MSD’S)

• Carpal Tunnel Syndrome

• Muscle Strains

• Shoulder Pain & Soreness

• Elbow Tendonitis

• Plantar Fasciitis

6

Who is at Risk? Repeat the same motion throughout their workday

Must do their work in an awkward position

Use a high force to perform their job

Repeatedly lift heavy objects

Combination of risk factors

Ergonomics

• Primary focus of an ergonomics program is the reduction of WMSD

• This is accomplished through the management of employee exposure to workplace hazards» Awkward postures» Forceful exertions » High rates of repetition

7

Ergonomics (er'gõ nom'iks): 

The study of work and the relationship of work to the physical and cognitive capabilities of people 

Fitting the job (tools, tasks, and environment) to the employee, instead of forcing the worker to fit the job

Ergonomic principles derived from many areas, including:

Biomechanics

Physiology

Anthropometry

Industrial engineering

Safety

What is Ergonomics?

Fitting the Workplace to the Person

8

Ergonomics

OSHA defines ergonomics as:  

… the science of “designing the job to fit the worker, instead of forcing the worker to fit the job.”

Lathe Operator

9

Normal guy

Perfect Lathe Operator

• Risk Factors inherent to 

the Task

• Risk Factors inherent to 

the Worker

• Risk Factors inherent to 

the Environment

Occupational Ergonomics

10

Why do Injuries Occur at Work?

• Job Design & set-up

• Job demands exceed employee capabilities

• Failure to account for human physiological

limitation

• Work stress (psychosocial factors)

• Failure to account for body size differences

One of many factors that contributes or creates an undesired outcome (MSD) and if eliminated would have prevented the 

undesired outcome!

Have to start with analyzing Workplace Risk Factors!

11

Risk Factors inherent to the Task

• In the picture, the worker is moving a box from the pallet to a dolly. Using the dolly eliminates forceful exertions needed to carry the box, but when he moves the box to the dolly, he is exposed to two risk factors: forceful exertions and awkward postures

12

Ergonomic Risk Factors & Hazards for WMSD’s

Repetitive Motions 

Awkward Postures  & sustained

Forceful exertions

Pressure points (contact stress) 

Vibration 

Repetitive Motion

• Duration of task

• Frequency of task

• Speed of work or cycle time to do each cycle 

• Productivity requirements

13

Repetition

Repeating the same motions every few seconds or repeating a cycle of motions involving the affected body part more than twice per minute for more than 2 consecutive hours in a workday.

Using an input device, such as a keyboard and/or mouse, in a steady manner for more than 4 hours total in a workday.

Source: OSHA

Repetitive Motion

Is often a concern in:

assembly tasks

sorting tasks

loading or off-loading materials

inventorying products

product stocking

software programming

telemarketing

customer service

14

• Repetition:

– Use power tools when available

– Use shortcuts on keyboard

– Use ergonomic products (trackball)

– Change tasks, stretch, or take a break from repetitive tasks

– Follow job rotation policies where applicable – effective job rotations work alternate muscle groups between successive job functions

Ergonomic Tips to Minimize Repetition

15

Awkward Postures

Positions that require more effort than others or that result in compression or stretching of the tissues in or around joints

Non-Neutral

Examples:Overhead Reaching

Twisting

Forward Bending

30

ECI’s Guidelines ‐ Awkward Postures 

Hands/Wrists Flexed ≥ 45°

Extended ≥ 45°

Ulnar Deviation ≥ 30°

Radial Deviation ≥ 30°

Elbows Elbow Extension ≥ 135°

Fully Rotated

“wings”

Shoulders Arm Raised ≥ 45°

Arm behind body

Shoulders Shrugged

Neck Flexed ≥ 30°

Extended

Twisted ≥ 20°

Sideways

16

31

Awkward Postures – cont’d 

BACK

Flexed ≥ 20°

Twisted ≥ 20°

Extension

Sideways

Unsupported (chair)

LEGS

Kneel

Unsupported

Partial Squat (45°)

Awkward Postures are caused by:

• Location of parts, equipment or  tools

• Position of parts, equipment or tools

• Design of parts, equipment or tools

• Employee work habits (choice vs. design)

17

BACK

• Flexed ≥ 20°• Twisted ≥ 20°• Extension• Sideways• Unsupported (chair)

18

35

36

19

37

20

2010 IAOHN Conference

Proper Sitting Position

40

PARTIAL Forward Bending

21

• Flexed ≥ 45°

• Extended  ≥ 45°

• Ulnar Deviation

• Radial Deviation

Risk Factors for the Hands and Wrists

42

Wrist – Use straight wrist positions

Working with bent wrists decreases grip strength

Use tools that let you keep your wrist straight

22

43

Neutral vs. Non‐Neutral

Common Keyboard Position

2010 IAOHN Conference 44

23

ELBOWS

•Elbow Extension ≥ 135°•Fully Rotated•“wings”

Arms Away from Body

24

Excessive Reaching

Move keyboard and mouse closer to you, adjusted to approximately  elbow height. 

ELBOWS IN

Elbows out andwrists bent

Are elbows relaxed and resting by the torso during keying or mousing?

Keyboard Position ‐ Arms by your side

25

SHOULDERS

• Arm Raised ≥ 45°• Arm behind body• Shoulders Shrugged

Source: 40” horizontal repetitive reach for sander located on the side wall. In addition, the employee will reach for tools and parts resulting in elbow extension.

Raised Shoulders

26

SHOULDER SHRUGGED & RAISED

NECK

• Flexed ≥ 30°• Extended • Twisted ≥ 20°• Sideways

27

Forward Head

Your head weighs??

Forward head posture puts up to three times more force on the base of your neck

Headaches are associated with this posture

28

Neck: Twist >20°

Forceful Exertions

Lifting bag weighing 50 lbs.  Lifting manhole cover weighing 75lbs. 

29

Ergonomic Tips to Minimize Force• Use mechanical lift assists and carts 

when available

– Avoid manually handling heavy objects (more than 35 pounds)

– Avoid carrying objects more than 100 feet

• Practice Proper Cart Handling 

– Push instead of pulling

– Use both hands when pushing

– Stand directly behind the cart when pushing (avoid twisting your body)

– Maintain good control and limit speed

– Ensure cart is not overloaded

Pushing versus Pulling

• Force exerted by the body

– Type of wheels

– Types of bearings

– Type of surface

– Slope of surface

– Handle height

30

Pushing versus Pulling

• Force exerted by the body

– Pulling force 

• Flex spine

• Back muscles contracting > ⇑ compressive forces

Pushing versus Pulling

• Force exerted by the body

– Pushing force

• Abdominal muscles are more active

• Less compressive force

31

Pushing versus Pulling

• Control options

– Keep forces low• Initial and peak

– Handle height between hip and shoulder

– Large wheels

• To ⇓ friction

– Slip resistant shoes

– Good housekeeping

– Good steering mechanism

– Incline surfaces < 2

Ergonomic Tips to Minimize Force• Use proper lifting techniques when 

lifting– Examine the load and the 

surrounding area– Bend knees when lifting a load– Look forward to keep back straight– Position the load close to the body– Maintain a firm grip on the load– Use smooth, controlled movements– Keep arms in front of body– Turn feet in direction of movement 

to avoid twisting

Get help before performing tasks  requiring excessive force

32

A lift, hoist or other mechanical assistance 

is unavailable

The object is heavier than you are capable 

of lifting alone (typically more than 35 

pounds) 

The object is not heavier than what two 

people are capable of lifting (typically less 

than 60 pounds)

The object is awkward or oversized.

Any object that does not have its weight 

equally distributed within the load.

Remember some objects are too heavy 

or awkward to be handled with two 

people

A Two‐Person Lift Is Appropriate When. . . 

Ergonomic Tips to Minimize Force

Ergonomic Tips to Minimize Force

• Use the correct tools / powered tools for the task

– Powered tools tend to require less exertion to perform a task

– Ensure that the weight of a powered tool (and cording) does not create additional force issues

• Use only the amount of force necessary to complete the task 

33

Minimize Pressure Points

Contact: Forearm

Before

Minimize Pressure Points

34

Contact: Fatigue MatContact: Hard Floor

35

Treatment for Plantar Fasciitis

• ErgoMates: Anti-fatigue mat on the shoe. Protects the feet where you walk.

• Do calf stretches• Stretch calves before

getting out of bed.• Ice with water bottle!• Use golf ball to massage

heel. Roll heel over ball.

Ergonomic Tips to Minimize Contact Stress

• Select hand tools that conforms to the geometry of the hands

• Pistol grip & in‐line tools:– Recommended handle length: 5.0 inches– Recommended handle diameter: 1.0 to 1.5 inches

• Pliers & crimping action tools:– Recommended handle length: 4.0 inches (minimum)– Recommended handle span: 2.5 inches

• Avoid handles that end in the palm of the hand

4.0 inches

36

Ergonomic Tips to Minimize Contact Stress

Avoid pressure on knees:– Avoid kneeling on hard surfaces for prolonged periods– Use knee pads when kneeling tasks are unavoidable

Avoid pressure on palms, wrists, and elbows: Use padding on hard or sharp surfaces

Change your position to eliminate the stress

Vibration

Using tools or equipment that typically have high vibration levels (such as chainsaws, jack hammers, percussive tools) for more than 30 minutes per day.

Using tools with moderate vibration levels (such as jig saws, grinders, etc.) for more than two hours per day.

Source: OSHA

37

• Hand‐arm vibration measurements and analyses should be performed according to ANSI S3.34, ACGIH‐TLV, and NIOSH 89‐106 recommendations.

• Any and all vibration is hazardous. 

38

Vibration Values

Die Grinders Vibration Value (m/s2)

Dotco

12L2500-36

90 psi/23000rpm3.5

3M

20237

20,000rpm

< 2.5

Dynabrade - 52669

Straight-Line Die Grinder

1.9

Dotco - 52679

6” Straight-Line

Extension

4.2

Ergonomic Tips to Minimize Vibration & Torque

• To lessen vibration:– Pad tool handles with a soft compressible surface– Use vibration damping (gel filled) gloves

– Select tools (hammers and chippers) with built in damping systems (springs/hydraulics) 

• To lessen torque reaction:– Use electric tools as opposed to air driven tools– Use pulse tools or auto‐shutoff tools

39

Human Factors

• People are Different

• People have Limitations

• People have Predictable Reactions

Risk Factors inherent to the Worker

• Age ‐ 26% in the 45‐54 age category

• Gender

• Physical Activity

• Strength

• Athropometry

40

Risk Factors inherent to the Worker

• Age ‐ 26% in the 45‐54 age category

• Gender

• Physical Activity

• Strength

• Athropometry

41

Incorporate Movement: Treadmill Walkstation

Energy Expenditure• Aerobic activities

– Produce whole body fatigue• Fast paced: lifting, lowering, walking, climbing

• Repetitive lifting > overexertion injury

– Factors affecting aerobic capacity• Gender

• Age

• Physical fitness

• Nature of work

• Whole body

42

Energy Expenditure: Control Options

• Effect of the workload

– Lifts versus trips• Fatigue versus spinal compression

• Lifting technique

• Efficiency

– Amount of work

– Endurance

• Work pace

– Heavier object

– Heavier body weight

• Lift versus lower

– Lower less energy

• Carrying location

– Center of gravity

Risk Factors inherent to the Worker

• Age ‐ 26% in the 45‐54 age category

• Gender

• Physical Activity

• Strength

• Athropometrics

43

Different Shapes & Sizes

44

Behavioral & Cognitive

• Daily time at workstations (personal vs. work)

• Design vs. User’s behavior

• Lack of "ownership" in personal safety on the part of the employee. 

“IT WON’T HAPPEN TO ME!!!!”• Lack of adjustable furniture at some worksites

• Lighting

• Temperature

• Vibration & Shock

• Noise, etc.

Risk Factors inherent to the Environment

45

Ergonomics Improvement Process

1. Analyze Issues

2. Identify root causes or source of problem

3. Identify Improvements

4. Justification of cost or improvements

5. Follow Up to verify improvements

Ergonomic Consultants of Indiana

11595 N. Meridian St., Ste 140

Carmel, IN 46032

(317) 708 ‐ 4832

Services: www.eci‐in.com

Ergo Products: www.myergoplace.com