Test 3 Material Flashcards
Definition of physical work capacity or recommended work rate
capacity to generate metabolic energy during continuous work over an extended time
Why evaluate PWC?
compare with physical work demands, identify high-risk workers, assess “return to work” status, understanding how individual factors affect PWC
Aerobic metabolism characteristics
slow production of ATP
used for lower intensity/most tasks and can be sustained for long periods of time, efficient(36molecules), CO2 and water as biproducts
Anaerobic metabolism characteristics
quick production of ATP but short duration, used for high intensity tasks, inefficient(3molecules), CO2/water/lactic acid biproducts
Aerobic Capacity Definition
maximum capacity to utilize oxygen AKA VO2max
What are 2 ways to determine recommended work rate
as a flat percentage, predict based upon AC and working time
What is Energy expenditure
metabolic demands of a task, usually quantified as a rate.
What percentages of AC should EE be below?
generally 50%, but NIOSH 33%
What are direct ways to determine energy expenditure of a task?
measure o2 consumption of a person performing the task
What are indirect ways to determine EE of a task?
- ) average values reported for various tasks
- ) subjective ratings
- ) estimate from heart rate
- ) task analysis
What is a MET?
Metabolic equivalent of task
What are the components of our metabolism?
Basal metabolism(EE required for body to function), activity metabolism(EE required to perform specific activities), digestive metabolism( EE required to digest food)
MET equivalents (1 MET =
3.5 mlO2/(kgmin), 1EE of sitting quietly, 1kcal/(kgfr)
What parts of your metabolism are included in a MET calculation?
BM and AM
VO2max Calc
Practice this
T/F: Fatigue is a task related risk factor
True!
Attributes of Acute fatigue
short term, temporary state, occurs in response to work demands and/or stress, can progress to chronic fatigue if there is not enough recovery period or over extended period of time.
attributes of chronic fatigue
longer term, often considered an illness, associated with persistent tiredness
Hierarchy of fatigue
Top: total fatigue,
Middle: mental fatigue, physical fatigue
Under physical: central, peripheral
Definition of mental fatigue
psychological and physiological state resulting from prolonged cognitive activity
symptoms of mental fatigue
weariness, reduced motivation, reduced alertness, reduced mental performance
definition of physical fatigue
inability to continue physical exertion at the level of one’s normal abilities, or a decreased capacity to generate force or expend metabolic energy
Symptoms of physical fatigue
physical discomfort, decreased mechanical output, loss of fine motor control
definition of peripheral fatigue
metabolic changes in the muscle itself or nerves from CNS to muscle
central fatigue
changes in the control of muscles originating in the CNS
definition of localized muscle fatigue
physical fatigue that can include central and physical fatigue, but it localized to a specific muscle or muscle group, can be measured by subjective or objective methods
symptoms of localized muscle fatigue
decline in muscle force capacity, localized pain and cramps, decreased motion control and accuracy, observable effects on productivity and performance
definition of strength
maximum joint moment or external force that can be generated. short term effort
definition of endurance
time duration an exertion level can be sustained until exhaustion. longer term effort
what kind of exertions is endurance a common measurement for?
isometric, isotonic
endurance time is when:
capacity is < demand
What kind of relationship is there between endurance and exertion level
nonlinear, backwards J
What kind of control is worker selection?
administrative
What are three major ergonomic approaches for improving safety and efficiency in industry?
job design, worker selection, worker training
What is Worker’s Compensation
state-mandated insurance that provides wage replacement and medical benefits to employees injured in the course of employment. In exchange, the employee relinquishes the right to sue their employer for negligence.
What is the court case that changed worker comp requirements?
Village v general motors
What is OSHA Act of 1970?
- ) Established OSHA to set and enforce workplace standards
- ) established NIOSH
- ) General duty clause (free from hazards workplace)
- ) Record keeping of substantial occupational injury and accidents. Also maintaining records onsite
T/F: there are numerous industry specific ergonomic standards set by different agencies
true
What is the purpose of the ADA?
To provide a national mandate to eliminate discrimination against persons with disabilities
What should an employer do when an individual’s disability creates a barrier to employment
Must consider whether a reasonable accommodation could remove the barrier
If functional impairment impedes job performance, what should an employer do?
reasonably accommodate the impediment, unless doing so poses an undue hardship
Ex. of reasonable accomodations
job restructuring, modifications to existing facilities, equipment, or work schedules, reassignment to vacant positions, provisions for readers and interpreters
Procedure for Time study step one
- ) watch until familiarity
- ) define a clear beginning/end point
- ) break the assembly down into steps
what is work measurement?
systematic determinatino of the length of time it should take to complete a job
What does work measurement help?
plan production, determine time required per task, establish productivity standards, determine product cost
Standard time definition
the time required for an average, qualified worker, working at a normal pace, to perform an operation and achieve a standard performance
What is a time study?
most widely used work measurement technique.
What are the direct observation measurement techniques?
time study and work sampling
Why is rating worker performance important?
people do not work consistently from day to day or minute to minute
what is standard performance?
100%, rate of output achieved by the qualified workers without over-exertion, using standard method
How to calculate NT
= observed time * rating/100
What are different allowances?
personal needs, fatigue, delays
What are allowances for?
increase standard time to compensate for losses in time
Standard time equ
ST = NT + (1+allowances)
Adv of work sampling over time study
doesn’t require continuous observations, better for jobs that have long cycle, total observation time is typically shorter
Adv of time study of work sampling
more detailed analysis of job elements
What does the elemental ratio study determine?
determine the percentage of total time that each element of a work task takes
What does the performance sampling study determine?
percentage of total time that each element of a work task takes AND evaluates performance rating
What does the time standard development study determine?
percentage of total time that each element of a work task takes AND evaluates performance rating AND develops time standards
When would you use a predetermined time system as a work measurement technique?
when there are no machines, no assembly stations, no operators to study.
How does a PTS develop time standards?
Breaks all work into standard motions with a time value assigned.
Adv of PTS
- ) can develop time standards before a job is started
- ) can find inefficiencies and standardize job procedures
- ) does not require a performance rating therefore more accurate and less subjective
- ) can be used to quantify learning time and performance rating for worker evaluation
Disadv of PTS
- ) significant training time before consistent results
- ) difficult when studying machine-based operations
- ) not all PTS will give good standards for all work
