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Assessment%20of%20Physical%20Capacity%20and%20Job%20Demands

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Job Analysis and Work Assessment Readings Jackson Ch 14 - Louhevaara Ch 70 - Anderson Ch 72 - Key – PowerPoint PPT presentation

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Title: Assessment%20of%20Physical%20Capacity%20and%20Job%20Demands


1
Job Analysis and Work Assessment
  • Readings
  • Jackson
  • Ch 14 - Louhevaara
  • Ch 70 - Anderson
  • Ch 72 - Key

2
Outline
  • Introduction - general outcomes and applications
  • Job analysis
  • Introduction
  • Variables that influence performance
  • methodology
  • Applications (assessment)
  • Fitness
  • Job placement Assessment
  • Functional Capacity Assessment
  • Validity of job analysis / Assessment

3
Job Analysis and Work Assessment
  • It is important to know what we are demanding
    from an individual in a work (or sport) situation
  • Ensure performance demands do not exceed
    capabilities
  • Relates to
  • Injury prevention
  • Job performance
  • Maintenance of work ability
  • Information is utilized for
  • Job redesign / ergonomic intervention
  • Development of valid cutoff scores for job
    placement assessment (JPA)
  • Assessing functional capacity for return to work
    following injury (FCA)
  • Detailed job analysis will provide us with the
    necessary information

4
Job Analysis
  • Goal is to identify the important work behaviours
  • Reduce job actions to words
  • essential component in developing pre employment
    test
  • JA utilizes a combination of approaches that
    include gathering
  • Psychophysical data
  • Biomechanical data
  • and physiological data
  • Methods may include
  • Questionnaires, checklists and surveys
  • interviews / Observations
  • Video analysis
  • Task simulations
  • Measurements (weight, height, EMG, HR, VO2,
    distance)

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6
Job Analysis - Methods
  • Psychophysical
  • Worker rates tasks on survey or performs
    simulations
  • RPE - rate of perceived exertion - Borg or Likert
    scales
  • Perception in terms of - CV demand, movement
    quality and strength (general / localized)
  • Biomechanical methods
  • heights and weights of objects lifted
  • forces - opening, pulling, pushing
  • evaluate potential stress on lower spine
  • video or physical evaluations of simulations
  • Physiological - CV components, blood analysis
  • O2 use, HR, lactate, pH, hormone, ion,
    ATP, CP

7
BORG Scales
Old BORG RPE SCALE New BORG RPE SCALE HR Max VO2 max
6 7 8 Very,very light .5 Very,very weak
6 7 8 Very,very light 1 Very weak
9 10 Very light 2 weak
9 10 Very light 3 moderate
11 12 Fairly light 4 Somewhat strong 52-66 31-50
11 12 Fairly light 5 Strong 52-66 31-50
13 14 Somewhat hard 6 61-85 51-75
15 16 Hard 7 Very strong 86-91 76-85
15 16 Hard 8 86-91 76-85
17 18 Very Hard 9 92 85
19 20 Very,Very Hard 10 Very Very Strong
19 20 Very,Very Hard Maximal
8
Injury Rates
  • Pre-employment tests are used to reduce work
    injuries
  • some jobs - high low back injuries
  • not serious but prevalent - 80
  • lifting, twisting, bending, pulling
  • 3 Ergonomic approaches to reduce back injuries
  • job Redesign
  • Engineering approach to reduce exposure to risk
    factors
  • pre employment testing
  • Preferred approach for physically demanding jobs
    that cannot be redesigned
  • Select individuals with capacity to safely
    perform job
  • Relationship between probability of injury and
    the of capacity to perform task
  • education and training
  • Train to lift properly - not successful

9
Job demands and Physical Fitness
  • when redesign is not feasible, fitness becomes
    important
  • secondary preventative measures
  • individual health promotion
  • healthy satisfying lifestyle
  • maintaining work ability / healthy aging
  • Fitness training / nutrition

10
Physical work load
  • Affected by - use of strength, frequency of
    peak loading, work/rest ratio, environmental
    factors, intensity
  • level of strain depends on demand and individual
    capacity
  • optimal / acceptable demand
  • cardio, muscular and psychosocial strain
  • physiological changes
  • fatigue
  • specific local changes (small muscles)
  • if job demands
  • do not exceed capacity - adaptation
  • too high - fatigue, dec productivity
  • prolonged / repetitive - damage / injury
  • Muscular work at the proper intensity, frequency
    and duration will produce fitness training effects

11
Physical Fitness
  • Fig 14-3 dimensions of Fitness
  • CV capacity (aerobic, anaerobic)
  • muscular performance
  • motor coordination
  • based on physiological demands and Anthropometric
    characteristics
  • Utilization of capacity requires voluntary
    control - therefore all linked to MOTIVATION
  • optimal situation - harmony between demand and
    fitness
  • Situation is highly dynamic
  • Text looks at specifics of Police, Fire and
    Professional Cleaners

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13
Fitness and Injury
  • Fitness level appears to be inversely related to
    injury
  • High levels of aerobic fitness, strength and
    flexibility were inversely related to workers
    compensation costs of fire fighters
  • Fitness programs should reduce musculoskeletal
    injuries
  • Only 20-40 of employees will use work site
    exercise facilities
  • Only 33 of these will train at the appropriate
    frequency, duration and intensity

14
Fitness and Productivity
  • Physical exercise is one of the basic elements in
    maintenance of work ability
  • linked with productivity, quality of work,
    absenteeism, and turnover rate
  • Exercise programs must be tailored to job demands
  • successful intervention requires
  • commitment and support
  • management and staff
  • use of work time (for at least part)
  • feedback and strong motivation
  • positive experience with exercise
  • skill full instruction
  • confidential, voluntary and no guilt

15
Physical Ability Testing
  • Ch 70 - Anderson
  • Ergonomics - alter the demands of the job to
    match the worker-redesign
  • Alternative approach is to match workers to the
    job, based on physical abilities
  • decline of 20-40 in injury rates when physical
    ability testing is implemented
  • Effectiveness depends on ability of test battery
    to assess what it intends
  • requires
  • thorough job analysis
  • carefully chosen job placement tests - measure
    only taks deemed essential by job analysis
  • validation that tests predict performance on the
    job
  • courts prefer testing to be focused on ability to
    perform not injury risk

16
Assessment
  • Cost / Benefit of Testing
  • cost of not being able to perform task
  • probability of individual lacking ability
  • Use normative data bases for different
    components.
  • Use of standard protocols necessary
  • balance with cost of testing applicants
  • Would it be more cost effective to redesign job?

17
Assessment
  • Test Battery Design
  • test requires a high degree of relatedness to
    essential function
  • Use realistic cutoff scores and normative data
  • accurate - precisely measures attribute it says
    it measures
  • reliable - yields same results
  • over time and by different testers
  • objective rather than subjective tests
  • All applicants must be treated fairly
  • all must be tested after same preparation and
    awareness
  • same re-testing procedures

18
Assessment of Worker Capacities
  • Workers compensation costs can be very high
  • Knowledge of worker functional capacities
    important to reduce these costs
  • Knowing workers capacity is important
  • For decision to hire (JPA)
  • For decision to return to work (FCA)
  • Fig 72-1 - Key
  • FCA- Functional Capacity Assessment
  • return to work testing process
  • individual physical functional work related
    capability
  • confirmation of meeting or not meeting minimum
    physical requirements
  • goal of FCA is return to work ASAP - even if
    limited capacity, some pain - may be modified
    tasks initially

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20
Job Placement Assessment (JPA)
  • Provides data prior to hiring
  • assists managers - reduce injuries
  • JPA - specific, objective, standardized protocols
    accurate and repeatable
  • Identify employees capability for lifting,
    carrying, pushing, pulling
  • Goal -accurately match worker with job
  • Components of assessment fig 72-2
  • weighted capabilities -CV, posture
  • tolerance and endurance capabilities
  • establish safe limits for work day
  • Validity of participant - honesty
  • fig 72-3 - less dishonest than generally assumed
    (5)
  • utilize database correlation to confirm
  • push vs pull, HR response at exertion

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22
Worker Assessment Principles
  • Principles for selecting FCA
  • must contain standards for identifying validity
    of participation
  • methodology must be consistent
  • utilize standard equipment
  • administrators must be trained and objective
  • processing of results must be standardized
  • Fig 72-5
  • reports should compare results with demands of
    job
  • unbiased and defendable decision about return to
    work

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24
Outcomes
  • FCA - dec re-injury rates
  • decrease lapse of time before return to work
  • decrease incidents and costs
  • JPA - reduce injury and lost days
  • eg fig 72-6 paper manufacturer
  • pre and post JPA implementation

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26
Validation Strategies
  • Determine whether test actually measures
    important work behaviors
  • Validity depends on reliability and relevance
  • Reliability - ability to differentiate among true
    levels of performance
  • Relevance - defining qualities being tested
  • Content validity
  • work sample or simulation of work
  • Test represents the content of the job
  • Relevance is clear and logical
  • Disadvantages - safety, not maximal capacity

27
Validation Strategies
  • Criterion related validity
  • Criterion - standard of judgment
  • Test successful people to determine what is
    required - use this to develop standards for
    success
  • significant correlation between pre employment
    test and job performance
  • Concurrent / predictive
  • Statistical validity
  • prospective - test individual applicants - do
    not use results in hiring - analyze performance
    of all individuals hired
  • productivity, retention, injury rate, evaluation
  • Compare to assessment results
  • Fig 70-1 - injury rate twice as high in those who
    failed screening test
  • Or, implement test in hiring practice, and
    compare to those hired previously
  • lack of control for other factors

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29
Validation Strategies
  • Construct Validity
  • Establish that a construct is required for job
    success
  • Use test that measures that same construct
  • The degree to which a test measures an attribute
    that cannot be directly measure (coordination)
  • link important constructs and multiple indicators
    of job performance
  • Tests theoretical and empirical relationships
  • Relationship between physical ability and job
  • Eg, biceps used to lift box, test bicep strength
    using barbell, establish cutoff based on weight
    of boxes
  • FDNY physical ability test was found to
    discriminate against women as constructs were not
    related to the job

30
Cut off scores
  • Cut Score
  • The test score that an applicant must obtain to
    be considered for a job
  • Difficult to establish and justify
  • Should they be relative to capacity, or absolute?
  • Should someone be hired who just meets the
    minimal requirement?
  • General Recommendations
  • Cardiovascular - max of 40 of VO2 max for 8 hr
    day
  • If peaks are higher, work / rest should be
    designed to keep average below 40
  • Evaluate large number of subjects
  • If 75 rate as acceptable, dec injury by 33
  • Muscle work - Snook and Ciriello (1991)
  • Table 21.2 (Gallagher)

31
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32
Summary
  • Employers are using pre-employment tests to
  • enhance worker productivity
  • to minimize the threat of litigation for
    discriminatory hiring practices
  • and to reduce the risk of musculoskeletal
    injuries.
  • The most common reason for ruling an employment
    practice invalid is the failure to show that the
    test measured important job behaviours.
  • Proper job analysis will help ensure validity.

33
Muscular Function Assessment
Gallagher - OEH Ch 21(CCW)
34
Outline
  • Muscle strength is a complex function that can
    vary with the methods of assessment
  • Definitions and introduction
  • Assessment methods
  • Variables impacting performance

35
Muscle Function
  • Gallagher
  • Strength - capacity to produce a force or torque
    with a voluntary muscle contraction
  • Power - Force distance time-1
  • Endurance -ability to sustain low force
    requirements over extended period of time
  • Measurement of human strength
  • Cannot be measured directly
  • interface between subject and device influences
    measurement
  • Fig 21.1 Biomechanical eg.
  • Q (F a)/b or c or d
  • force from muscle is always the same
  • results are specific to circumstances
  • dynamic strength - motion around joint
  • variable speed - difficult to compare
  • static or isometric strength- no motion
  • easy to quantify and compare
  • not representative of dynamic activity

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37
Factors Affecting Strength
  • Gender
  • Age
  • Anthropometry
  • Psychological factors - motivation
  • table 21.1

38
Factors Affecting Strength
  • Task influence
  • Posture
  • fig 21.2 - angle and force production
  • Duration - Fig 21.3
  • Velocity of Contraction - Fig 21.4
  • Muscle Fatigue
  • Static vs dynamic contractions
  • Frequency and work / rest ratio
  • Temperature and Humidity
  • inc from 20-27 C - decrease of 10-20 in muscle
    capacity

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40
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41
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42
Strength Testing (intro)
  • Isometric strength testing
  • standardized procedures
  • 4-6 sec contraction, 30-120 sec rest
  • standardized instruction
  • posture, supports, restraint systems, and
    environmental factors
  • worldwide acceptance and adoption
  • Dynamic strength
  • isoinertial (isotonic)- mass properties of an
    object are held constant
  • Psychophysical - subject estimate of (submax)
    load - under set conditions
  • isokinetic strength
  • through ROM at constant velocity - no
    acceleration or deceleration
  • Uniform position on F / V curve
  • Standardized
  • Isolated muscle groups
  • Research and rehabilitation

43
Strength Testing
  • Testing for worker selection and placement
  • Used to ensure that worker can tolerate physical
    aspects of job
  • similar rates of overexertion injuries for
    stronger and weaker workers
  • Key principles
  • Strength test employed must be directly related
    to work requirements
  • must be tied to biomechanical analysis
  • Isometric analysis fig 21.5
  • for each task - posture of torso and extremities
    is documented (video)
  • recreate postures using software
  • Free body diagrams (Kin 201)
  • values compared to pop. norms
  • industrial workers
  • estimate capable of level of exertion
  • predict stress on lumbar spine

44
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45
Isometric Considerations
  • Discomfort and fatigue in isometrics thought to
    result from ischemia
  • Increasing force, increases intramuscular
    pressure which approaches then exceeds perfusion
    pressure - lowering then stopping blood flow
  • Partial occlusion at 20-25 MVC
  • Complete occlusion above 50 MVC
  • Fig 15-19 Astrand
  • Max hold time affected by MVC
  • Recommend less than 15 for long term
    requirements
  • Fig 15-20 Astrand
  • With repeated isometric contractions Force and
    Frequency influence endurance
  • Optimal work / rest ratio of 1/2
  • Duration important as well (Astrand - blood flow)

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47
Isoinertial Testing
  • Consider - biomechanics and grip
  • Stabilization requirements
  • justification of cut off scores
  • Examples from industry
  • SAT - strength aptitude testing
  • air force standard testing
  • Pre-selected mass - increase to criterion level -
    success or failure
  • found incremental weight lifted to 1.83m to be
    best test as well as safe and reliable
  • PILE - progressive inertial lifting evaluation
  • lumbar and cervical lifts -progressive weight - 4
    lifts / 20 seconds
  • standards normalized for age, gender and body
    weight
  • variable termination criteria
  • voluntary, 85 max HR, 55-60 body weight

48
Psychophysical testing
  • psychophysical methods
  • workers adjust demand to acceptable levels for
    conditions
  • provides submax endurance estimate
  • Procedure -
  • subject manipulate one variable-weight
  • Either test starting heavy or light
  • add / remove weight to fair workload
  • Fair defined as without straining, becoming
    over tired, weakened, over heated or out of
    breath
  • Study must use large numbers of subjects
  • evaluate/design jobs within capacities of workers
  • 75 of workers should rate as acceptable
  • If demand is over this acceptance level 3 times
    the injury rate observed to occur

49
Psychophysical (cont)
  • Summary
  • Table 21.2 (Snook and Cirello) (see slide 31)
  • Advantages
  • realistic simulation of industrial tasks
  • very reproducible - related to incidence of low
    back injury
  • Disadvantages
  • results can exceed safe as determined through
    other methodology
  • biomechanical, physiological

50
Fire Fighters
  • 200 subjects - asked about job demands of
    physical fitness and aerobic power, muscular
    performance and motor coordination
  • smoke diving with SCBA- highest aerobic demand
  • clearing passages with heavy manual tools -most
    muscular demand
  • roof operations- highest motor control demand
  • Aerobic Power Demand then assessed- Table 14-1
  • often 2.1-2.8 L/min
  • max frequent 3.8 L/min 180 bpm
  • compounded by
  • need to disperse heat
  • no possibility of alleviating load
  • recommend minimum of 34-45 ml/min/Kg for VO2max

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52
Fire Fighters
  • Muscular Performance
  • biomechanical factors - simulated clearing task -
    9 kg power saw - floor to ceiling
  • high compression on L5/S1
  • 90 of isokinetic strength
  • back and knee extensors
  • Table 14.1 - determined that a minimum of good or
    excellent is needed for muscular performance
    measures
  • Bench press
  • Sit up
  • Squat
  • Pull up
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