Mechanical Work-Capacity Evaluation

Question 1

Worker selection

Answer 1

purpose of worker selection and placement programs is to assign the right worker to a particular job

Question 2

Why do we do worker selection?

Answer 2

Reducing injury risk
Performance
Human rights legislation

Question 3

Reducing injury risk

Answer 3

Avoid mismatch btw workers capabilities and the job demands
Workers injury compensation claims and costs to employer and insurance
Costs and losses for injured employee

Question 4

Performance

Answer 4

Physical levels required for execution of task
Minimum level of skill or excellence to be successful
As good as seasoned workers?
Training and retraining required
Several potential job postings

Question 5

Human rights legislation

Answer 5

Social justice and equal opportunity
ADA - limit amount of pre employment screening
Employment quotas and gov. contractors - more than 25 employees needs to be representative of the population
Equal employment opportunity commission - fighting to reduce discrimination

Question 6

Worker screening criteria

Answer 6

Safety
Accuracy
Sensitivity
Specificity

Question 7

Worker screening criteria - sensitivity

Answer 7

Detect workers who will develop disease or injury

Must detect true positives

Question 8

Worker screening criteria - specificity

Answer 8

Correctly identify workers who will not develop future problems
Must detect true negatives

Question 9

Worker screening tests

Answer 9

Medical history
General medical exam 
X rays
Anthropometry
ROM
Muscle strength - general fitness

Question 10

Screening tasks -

Answer 10

How to evaluate (screen) an individuals ability to perform work related tasks

Question 11

Interaction with the environment - depends on

Answer 11

Joint motion
Muscle strength (GMT)

Question 12

Planes of motion

Answer 12

Sagittal
Frontal
Transverse

Question 13

Axes of motion

Answer 13

Mediolateral (frontal)
Anterior-posterior (sagittal)
Vertical (transverse)

Question 14

Factors affecting ROM

Answer 14

Type of joint - injury, degenerative disease
Tissue arrangements
Clothing
Past injury
Age
Gender
Soft tissue ratio (mm:fat)
Multi-joint affect

Question 15

ROM workplace considerations - Individual

Answer 15

Joint motion reflects lifestyle

Joint motion reflects injury history

Question 16

ROM workplace considerations - environment

Answer 16

can be accommodated for reduced ROM

Question 17

ROM workplace considerations - task

Answer 17

can be assigned according to ROM

Question 18

Why it is important to understand and evaluate strength in the workplace

Answer 18

Many jobs require high levels of exertion

This has a direct impact on safety and performance

Question 19

Strength =

Answer 19

Capacity to produce force or torque with voluntary muscle contraction

Question 20

Max strength =

Answer 20

capacity to produce force or torque with a max voluntary muscle contraction

Question 21

Human strength

Answer 21

Voluntary mm contractions should only be measured by the effort the person is willing to put forth

Question 22

What is important when testing human strength

Answer 22

The test equipment
The tests persons familiarity
The interface btw the tested person and the test equipment

Question 23

Purpose of strength measurement in ergonomics

Answer 23

Worker selection/placement

Job design

Question 24

Worker selection/placement can serve to do what

Answer 24

reduce harmful physical effects caused by job/worker mismatch given adherence to three principles

Question 25

Three principles to adhere to

Answer 25

Strength measured closely simulates
Predictive value for who is at risk
The training/skills of the ergonomist administering the test

Question 26

Musculoskeletal disorders account for what percent of all lost workdays and illnesses

Answer 26

34%

Question 27

Muscle strength - neural factors

Answer 27

Synchronization - trainable
Recruitment - trainable
Summation - trainable
Neural quality (age factors)

Question 28

Muscle strength - psychological factors

Answer 28

Motivation - desire to return to work if evaluating post injury

Question 29

Muscle strength - physiological factors

Answer 29

Fatigue
Available energy
Both of these are trainable

Question 30

Muscle strength - mechanical factors

Answer 30

Length-tension relationship
Force-velocity relationship
Angle (posture) –> torque

Question 31

Torque (moment of force) –>

Answer 31

tendency of a force to cause rotation

Question 32

Torque =

Answer 32

force * distance

force * moment arm

Question 33

Moment arm

Answer 33

Perpendicular distance from line of action of the force to axis of rotation

Question 34

Moment arm and torque vary throughout

Answer 34

the ROM

Question 35

Individual muscles interact in what way

Answer 35

as a group to produce torque at a joint

Question 36

What we know about strength

Answer 36

Max force (torque) producing capability varies considerably btw people and btw tasks
Strongest 6-8 times stronger than the weakest
Static strength is not necessarily correlated with dynamic strength

Question 37

Additional gender issues with strength

Answer 37

Diff in upper body greater than lower body

Diff almost entirely explained by differences in muscle size

Question 38

Psychophysical limits -

Answer 38

Voluntary dec in max with inc dimensions of boxes
Dec with inc height (shoulder to above)
Male about 2x Female

Question 39

LOAD workplace summary - individual

Answer 39

Screen people for sufficient strength to a task

Load should not exceed capacity of least capable employee

Question 40

LOAD workplace summary - environment

Answer 40

Reduce package weight, alter layout, new equipment

Question 41

LOAD workplace summary - task

Answer 41

redesign, additional workers