Assessment of Physical Capacity
and Job Demands
• Occupational Ergonomics Handbook
– Ch. 14 Louhevaara
– Ch. 70 Anderson
– Ch. 72 Key
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Outline
• Physical job demands and fitness
– firefighters, police, cleaners
• Physical ability testing
– analysis, protocol design
• Assessing functional capacities
– principles
– outcomes
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Job Demands and Physical Fitness
• Job demands include:
– physical, mental and social loading factors
• ~20 % of work force in industrialized countries
exposed to heavy muscular work.
–  in dynamic jobs with simple tools
–  in static, repetitive tasks
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• When job redesign is not feasible, physical
fitness becomes important.
• Control measures affecting muscular work
performance through fitness are called
secondary preventative measures:
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individual health promotion
healthy satisfying lifestyle
maintaining work ability / healthy aging
fitness training
nutrition
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• Triangle strategy for maintenance of worker
ability (fig. 14.1):
– work and environment
• ergonomics, safety, hygiene
– organizational culture
• psychosocial, management issues
– individual worker
• fitness, satisfying lifestyle
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Physical Job Demands
• Physical job demands can be classified as:
1. Heavy dynamic work (forestry, police, firefighters)
– large muscle groups
– cardiorespiratory strain
–  with PPE
2. Manual materials handling (MMH) (factory, building)
– dynamic/static work with large muscle groups
– CV and muscular strain
3. Static postural work (electrical assembly)
– large and small muscle groups (musculoskeletal strain)
4. Repetitive work (secretary)
– small muscle groups (musculoskeletal strain)
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• Physical work load is affected by use of
strength, frequency of peak loads, work/rest
cycles, environmental factors and work
intensity.
• The level of physical strain depends on job
demands and individual capacity.
• Acceptable physical job demands for different
types of work depends on:
– cardiovascular strain
– musculoskeletal strain
– psychosocial strain
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• Acceptable job demands arises from the
principle that there are individual differences
for physical strain.
• When physical job demands:
– do not exceed capacity: adaptation (fast recovery)
– too high: fatigue,  productivity (slow recovery)
– prolonged / repetitive: injury/disease
• Muscular work at the proper intensity,
frequency and duration will produce fitness
training effects.
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Physical Fitness
• Dimensions of fitness (fig 14.3)
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CV capacity (aerobic, anaerobic)
muscular performance (strength and endurance)
motor coordination (flexibility, balance)
motivation
• Physical work capacity is based on physical
fitness.
– if the worker’s fitness and anthropometrics are in
harmony with physical job demands the situation is
acceptable
– this situation is highly dynamic
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Fire Fighters
• Lusa et. al 1994:
– 200 subjects rated task demands for aerobic power,
muscular performance and motor coordination
– smoke diving with SCBA had greatest aerobic
demand
– clearing passages with heavy manual tools had the
greatest muscular demand
– roof operations require high motor control demand
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• Aerobic Power Demand (Table 14.1)
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common tasks require 2.1 - 2.8 L/min
work rates often reach 3.8 L/min
heart rates reach near maximal levels
compounded by heat stress
researchers recommend min 34-45 ml/min/kg
• Fire fighter job demands can be extremely
high, and place a serious cardiovascular strain
on older individuals.
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• Muscular Performance
– biomechanical factors were evaluated
• simulated clearing task, 9 kg power saw - floor to ceiling
• high compression on L5/S1 (6228 N)
• Minimum muscular performance values (Table
14.1).
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Bench Press
Sit-up
Squat
Pull-up
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Police Officers
• Hard to alter job demands.
• The majority of work time can be sedentary.
• There are unexpected peak load situations.
• Many police officers become sedentary in middle age.
• With an intensive fitness training program, officers
reduced cardiovascular risk factors and  aerobic and
muscular fitness.
• Good selection criteria will guarantee an acceptable
level of fitness for new officers.
• After age 35 fitness should be tested regularly.
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Professional Cleaners
• Very common physically demanding occupation.
• The mean age is older than other professions.
• Requires aerobic capacity, muscular performance and
motor coordination.
• Fitness level needs to be higher than average agerelated values.
• Physical fitness training will improve performance.
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Physical Exercise and Fitness
• Physical exercise is essential for sustaining aerobic and
muscular fitness, and is linked with good work
performance regardless of the type of work.
• Exercise has a positive effect on productivity, quality of
work, absenteeism, and turnover rate.
• A high level of physical fitness is important in
sedentary jobs as it has a positive influence on mood.
• Thus exercise is a basic element in the maintenance of
work ability.
• Physical exercise must be tailored to actual job
demands.
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• Before starting physical exercise it is important
to perform an assessment of physical job
demands:
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Job load and hazard analysis
Measurement of heart rate
Estimation of energy expenditure
Rating of overall perceived exertion
Rating of local perceived exertion (back, arms)
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• Successful work-site physical exercise
interventions require:
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commitment and support of management
commitment of the work unit
exercise during work time
feedback and strong motivation
positive experience with exercise
skillfull instruction
confidential, voluntary and no guilt
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Physical Ability Testing
» Ch 70 - Anderson
• Ergonomics attempts to alter the demands of the job to
match the capabilities of the worker.
• An alternative approach is to match workers to the job,
based on physical abilities.
• Several studies have documented the importance of
physical ability testing.
• Injury rates  20-40% when physical ability testing is
implemented.
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• The effectiveness of physical ability tests
mainly depends on the ability of the test battery
to assess what it intends. This requires:
– a thorough job analysis
– carefully chosen tests
– validation that test predicts performance
• Courts prefer that the emphasis be on the
ability to perform the job rather than the risk
of injury.
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Job Analysis
• Identify the essential functions of the job.
– usually the functions performed most frequently
– infrequent function may also be essential
• Cost / benefit analysis
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if everyone can pass the test, why bother
cost of not being able to perform task
probability of individual lacking ability
balance with cost of testing applicants
• Can a job function that is difficult to do be
modified through ergonomics.
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Test Battery Design
• Test required to have a high degree of jobrelatedness to the 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
• Safe: reduce the risk of injury.
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Validation
• Statistical validation
– prospective statistical analysis
• test individuals when hired then track
performance over career
• measure productivity, retention, injury rate,
supervisor evaluation
• compare performance with test results
• Content validation
– demonstrate that the content of the job is reflected
in the content of the test battery
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Ongoing Practices
• Four aspects are crucial to assure that the test
battery is fair to all applicants.
1. All applicants must be treated fairly.
• same conditions
2. Same scoring process for everyone.
3. Same re-testing procedures
4. Take prior experience into consideration.
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Assessment of Worker Capacities
» Chapt. 72 Key
• Workers’ compensation costs can be staggering.
• Knowledge of worker functional capacities is
important for reducing workers’ compensation
costs.
• It is critical to know physical work capacity.
– decision to hire
– decision to return to work
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• Functional Capacity Assessment (FCA)
– return to work testing process that determines an
individual’s physical functional work related
capability
– confirmation of meeting or not meeting minimum
physical requirements
• The goal of FCA is return to work ASAP.
– even if at limited capacity, some pain
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Job Placement Assessment
• Provides data prior to hiring
– assists managers in making decisions
– potential to reduce future injuries
• JPA: specific, objective, standardized protocols
followed to allow for accurate and repeatable results.
– Identify an employees ability to: lift, carry, push,
pull and do other job specific activities.
• Goal: accurately match worker with job to increase
productivity.
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Components of Assessment
• Weighted capabilities
– ability to perform a specific task
– CV, posture
• Tolerance and endurance parameters
– sitting standing and workday tolerance
– establish safe limits for work day
• Validity of participant
– determine if someone is being dishonest
– less than we generally think (5%)
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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
• Assessment reports should compare results
with the demands of job.
– unbiased and defendable decision about return to work
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The Provider
• The provider of worker assessments are
instrumental in  return to work percentages.
• Physical and occupational therapists are the
primary providers of worker assessments.
• The therapist needs to provide objective,
unbiased data.
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Outcomes
• The primary outcomes of worker assessments:
–  reinjury rates
–  lapse of time before return to work
–  incidents and cost of litigation
• JPA can be very effective
– fig 72-6: paper manufacturer
• 70 employees
• went from 530 to 28 lost work days
• company saved $2,000,000
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• Mobile assessments are cost effective and
convenient for the employer and employee.
• Large trucks can be used for mobile
occupational health clinics.
– convenient for remote sites
• An onsite industrial therapist can be a very
cost-effective way for a company to meet its
needs.
–  down time
– prompt treatment
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