WORK DEMANDS
Physical Task
Demands
Work Content
Mental Task
Demands
Physical
Environment Demands
Non-physical
Environment Demands
Work
Context
Required
Qualification
Processor

Job placement assessment Job Modification
Work
Demands
Workers’
Qualification
Education &
Training
Work
Conditioning

weight of load repetition horizontal distance height of lift/lower duration twisting angle lifting/ lowering carrying pushing/ pulling other
Object
Handling
Demands
Extremity-Postural
Demands
Physical Demands
Work
Content
Mental Demands
Work Demands
Physical Environment
Work
Context
Non-Physical
Environment

Extremity postural
Demands
Seating
Standing
Walking
Kneeling
Squatting
One-legged
Crouching
Crawling
Climbing
Others

Repetitive work
Static work
Body segment
Force and Posture

Seating
Standing
Walking
Kneeling
Squatting
One-legged
Crouching
Crawling
Climbing
Others
Extremity postural
Demands
Dynamic work
Static

Energy
System
Cardiorespiratory
System
Flexibility
ROM
Aerobic
Anaerobic
Circulatory Function
Heart Function
Respiratory Function
Joint
Tissue
Muscular
Neuromuscular
System
Neural
Body
Composition
Fat Mass
Fat-free Mass

Stress S train
Biomechanical
Physiological
Psychological
Disorders

TISSUE RESPONSES TO PHYSICAL STRESSORS
Load
Response
Symptoms
Impairment
Disability
Adaptation

 Standing

 Circulation
 Muscle fatigue
 Joint compression

Develop and improve:
 Strength






Endurance
Cardiovascular fitness
Mobility
Flexibility
Work
Demands
Stability
Co-ordination, balance and functional skills

 Low back pain is the most common workrelated msuculoskeletal disorders, and cause most socio-economical burden.
 LBP claims account for 16% of all workers compensation claims and 33% of total claims costs
(Bernard et al., 1997)

 Prevalence
 percentage of people in a certain population who suffer from the condition concerned
 Point Prevalence
 percentage who are found to be suffering at a certain moment in time ( i.e. when the survey is conducted)

 About 70% of people will suffer from one or more episodes of LBP at some time or another during their lives
Bernard 1997




Local:
39% in general population (Lau et al., 1995)
58% in a group of manual handling workers

 Most episodes of LBP are relatively shortlived (subsided within 6 weeks).
 Recurrent rate is very high (60%)
Biering-Sroenson 1983

 6 months absence: likelihood of returning to work fall to about 50%
 After 1 year absence: 25%
 After 2 years absence: virtually nil

 Physical Factors
 Heavy physical work
 Lifting and forceful movements
 Bending and twisting
 Whole body vibration
 Static work postures
 Non-physical factors
 Psychosocial factors
Bernard 1997

EFFECTS OF PHYSICAL
ACTIVITIES IN THE PREVENTION
OF LBP
 Strong evidence that PA has a primary preventive effect on LBP

EFFECTS OF PA IN SECONDARY
PREVENTION (Van Tulder et al.,
2000)
 Acute LBP - strong evidence that exercise therapy is NOT more effective than inactive treatments or other active treatments.
 Low stress aerobic activity during the first 2 weeks is indicative to improve recovery and lessen disability.




Chronic LBP – strong evidence that exercise therapy and conventional physiotherapy are equally effective and exercise therapy is more effective than usual care by GP
Strong evidence that strengthening exercises are more effective than other types of exercise.
Strong evidence that exercise diminishes the musculoskeletal and cardiorespiratory effects

TYPES OF EXERCISE AND
TRAINING PRINCIPLES



FITT
TYPES: STRENGTHENING

STABILIZER

ENDURANCE

STRENGTH
TYPES: MOBILIZING



Relationship between the probability of injury and percentage of strength capacity used by the worker at work. (Chaffin 1973)
Relationship between the incidence of firefighter back injuries and level of physical fitness. 7.1% least fit, 3.2% moderate, 0.8% most fit (Candy et al., 1979)

EFFECTS OF A FOUR-WEEK
MUSCLE STRENGTHENING
PROGRAM ON MAXIMUM
ACCEPTABLE LIFTING LOAD
Yeung SS. et al., 1998

 Subjects= university students (N=19)
 Isokinetic measurements of back extensors, knee extensors, shoulder abductors, and elb. Flexors.
 Maximal acceptable lifting load
(psychophysical approach)

 4 WEEKS OF TRAINING
 LOAD: 80% PEAK TORQUE
 WEEKLY ADJUSTMENT BY 5%

 Significant training effect on MALL and back extensors

EFFECTS OF SQUAT LIFT
TRAINING AND FREE WEIGHT
MUSCLE TRAINING ON MAXIMUM
LIFTING LOAD AND ISOKINETIC
PEAK TORQUE OF YOUNG
ADULTS
WITHOUT IMPAIRMENTS
Yeung SS., & Ng GYF 2000

 36 University Students
 Training approach:
1. free weight muscle strengthening program;
2. Task specific training programme; and
3. Control

 Significant improvement in MALL and back extensors
 No significant differences between the training protocol

McGill 1998

 To stress both damaged tissue and healthy tissues for tissue repair but avoid excessive loading
 Exercises that challenge muscle but impose minimal joint loads







Frequency: most beneficial when performed daily
No pain No gain ?
General conditioning exercise is important
Endurance more protective value than strength
Flexibility (mobilizing) should best be performed at unloaded position
No fixed recipes, exercise should be tailored made

RA
EO
IO
LD
TES
LES
MF
19.7
21.9
Compression 2.3
1 leg ext 1 leg/arm prone ½ supp
3.3
8.4
12.0
8.1
5.7
4.0
16.2
15.6
12.0
11.5
4.7
4.3
12.1
11.2
66.1
3.1
3.7
12.7
6.5
45.4
28.4
31.5
3.2
59.2
51.9
4.3
57.8
47.5
4.3




Pr lying arch back
½ support back extension
Single leg extension with hand and knee support

ex QL PS EO IO TA RA RF ES
Sit-up (st) 24 44 15 11 48 16 4
Sit-up (kn bent)
12 28 43 16 10 55 14 6
Curl up (kn) 11 10 19 14 12 62 8 6
SLR 9 33 26 9 6 37 23 7
Side support 54 12 43 36 39 22 11 24






No single abdominal exercise challenges all of the abdominal musculature:
Curl-up challenges mainly RA
Sit-ups (leg straight or knee bent) = high psoas activation and disc compression
Leg raises causes even higher activation and compression
Isometric side support for QL



To facilitate a return to work or ensure an employee remains at work, ideally in his or her original job
Different terminology:work, industrial, vocational rehabilitation

Work
Conditioning
FCE
Work
Hardening
Injury Acute Mx
Work
Demand
Analysis
Work
Modification




Functional: Meaningful, useful and purposeful
Capacity: maximum ability and capability
Evaluation: Systematic approach including observation, measurement, reasoning and conclusion



Systematic, comprehensive approach
Objective and valid measurements to predict a person’s ability to perform work related tasks.




Generic - Baseline Capacity Evaluation
 Usually based on physical demands of DOT
Job oriented – Job capacity Evaluation

Focus on the match of the worker’s ability to the work demands of specific job
Worker oriented – Work capacity Evaluation

Determine worker’s capabilities to the basic demands of earning occupation



Ensure workers’ health and safety in job placement (OSHA);
Identify an individual’s physical abilities and limitations (ADA)
 Determine an injured worker wage-earning potential and return to work abilities
(Insurance company and legal profession)

EVALUATION SYSTEM
COMMONLY USED IN HONG
KONG

FCEs




ARCON
BLANKENSHIPS
TRACKER
BTE



ERIC
MVE Battery Tests
Non-computerized system

TYPICAL COMPONENTS OF FCES




Interview – patient information
Job analysis (questionnaire)
Behavioural profile
Physical measures/muscuoskeletal evaluation



Physiological measures
Functional measures
Comparison of testing with job requirements








Isometric strength test (6 positions)
Material handling test (3 positions)
Frequency of manual handling:
Occasional (0-33%), frequent (34-66), and constant (67-100%) manual handling
Hand function – hand and pinch grip
Fine hand dexterity
Non-materials handling test
Positional tolerance test





Arm Lift
Torso Lift
Leg Lift
High Far Lift


Floor Lift
High Near Lift








0-33% of the working day, <32 repetitions
Psychophysical approach
Floor to knuckle
Shoulder lift
Overhead lift
Carrying - 30 ft.
Pushing/Pulling - 30 ft.



33-66% of working day or 32-200 repetition per day.
4 lifts in 20 seconds



Maximum Grip Strength Test - Jamar
5-position Grip Test
 Rapid Exchange Grip Test



Sitting
Standing





Walking
Bending
Reaching
Squatting
Kneeling




Crawling
Climbing
Balancing
 Arm Controls / Leg Controls

Blankenshi p
Valpar
Jmed






Interview
Physical measures/muscuoskeletal evaluation
Physiological measures
Functional measures
Comparison of testing with job requirements






Standardized format
Hand Strength
Testing System
Pinch Strength
Testing System
Electronic
Goniometer
Lifting platform
Methods-Time
Measurement



Initial Occupational Assessment
Functional assessment



Advice or assistance in vocational reeducation
Advice or assistance in job-seeking
Work Conditioning






Occupational Rehabilitation Counselling
Functional Education
Workplace Analysis
Vocational Assessment
Vocational Re-education



Injured worker (worker’s family)
Physician




Therapist
Psychologist
Vocational specialist
Ergonomist



How much can this injured work perform?
Suitability of job


 job demand restrictions / limitation how to imposed






Initial Occupational Rehabilitation
Assessment
Functional Assessment
Vocational Re-education
Assistance in Job seeking
Working Conditioning

weight of load repetition horizontal distance height of lift/lower duration twisting angle lifting/ lowering carrying pushing/ pulling other
Object
Handling
Demands
Extremity-Postural
Demands
Physical Demands
Work
Content
Mental Demands
Work Demands
Physical Environment
Work
Context
Non-Physical
Environment

Seating
Standing
Walking
Kneeling
Squatting
One-legged
Crouching
Crawling
Climbing
Others
Extremity postural
Demands
Dynamic work
Static





A structured, goal-oriented, individualised program
To improve the biomechanical, neuromuscular, cardiovascular/metabolic, behaviour and vocational function
Education of injury prevention
Work-risk identification

 Training should be based on job requirement (job analysis) and work functional limitation (FCE)

Typical work conditioning program









Warm-up and stretching exercise
Cardiovascular training – ergometer, treadmill, stair-stepper
Lumber stabilization training – therapeutic balls
Strength & endurance training – circuit training
(multi-gym), dead wt, isokinetic training)
Balance – BAPS, therapeutic balls
Functional activities – MMH
Work simulation activities
Dexterity training – hand or upper limbs injury
(e.g. Perdue peg board, Valpar)
Education & pain management





Interdisciplinary use real or simulated work activities in a relevant work environment and conditioning tasks.
Address patient’s physical, behavioural and vocational needs
Daily sessions: 4-8 hrs/day

Difference between work conditioning and health related conditioning


Exercise prescription based on job requirement and FCE (job goal oriented)
Identifiable outcome measure (work nature that can be performed)
 Multiple components involves education components related to work

weight of load repetition horizontal distance height of lift/lower duration twisting angle lifting/ lowering carrying pushing/ pulling other
Object
Handling
Demands
Extremity-Postural
Demands
Physical Demands
Work
Content
Mental Demands
Work Demands
Physical Environment
Work
Context
Non-Physical
Environment

Seating
Standing
Walking
Kneeling
Squatting
One-legged
Crouching
Crawling
Climbing
Others
Extremity postural
Demands
Dynamic work
Static




Potential client
Chronic injured worker
Poor physical conditioning



Compromised cardiovascular status
Pain on activities
Psychosocial dysfunction

Conditioning Work conditioning Work Hardening
Strength
Endurance
Flexibility
Mobility
Stability
Co-ordination
Education
Training
Vocational
Rehabilitation
Psychosocial
Rehabilitation

REFERENCES




Key GL. (1995) Industrial Therapy, Mosby- YearBook
Inc., Chapter: 14-15, 21.
Isernhagen JS. (1997) Industrial Physical Therapy In:
Orthopaedic and Sports Physical therapy. Ed. Malone TR,
McPoil T. & Nitz AJ. 3 rd edition, Mosby.
Yeung, S.S., Chan, M.C., Leung, D.C., Ma, M.S., Tsang,
S.Y., 1998, The effects of a four-week muscle strengthening program on maximum acceptable lifting load, Journal of Occupational Rehabilitation , 8(4): 265-
272.
Yeung, S.S
., Ng, G.Y.F., 2000 Effects of Functional
Lifting Training and Free Weight Muscle Training on
Maximum Acceptable Lifting Load and Isokinetic
Peak Torque of Normal Young Adults. Physical
Therapy , 80:570-577.

 McGill SM. 1998, Low back Exercise:
Evidence for improving exercise regimens.
Physical therapy 78: 754-765.