Prevention of MSDs by workload optimization based on external and internal load assessment methods

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Prevention of MSDs by workload optimization based
on external and internal load assessment methods

• Danuta Roman-Liu
• Central Institute for Labour Protection
  National Research Institute

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Work incapacity due to MSDs in 2003 - 2005
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Work incapacity due to MSDs in relation to all
incapacities in 2003 2005
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Sectors with the highest rate of MSDs (according
to Polish National Labour Inspectorate)

• transportation
• agriculture, fishing, forestry
• mining
• building industry,
• wholesale and retail trade
• hotels and restaurants,
• health care

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Risk factors for MSDs
Work environment ? Biomechanical factors
posture force time sequences ?
Psychosocial factors job demands
control social support
Individual characteristics ?Genetically
determined inclination to diseases ?Personality ?G
ender ?Age ?Physical capacity

• Home environment
• ?Leisure time
• ?Diet
• ?Sport

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External and internal load at the work stand
External load can be assessed as a function of
parameters describing performed task (body parts
configuration, exerted force, time).
Internal load is the reaction of musculoskeletal
system to the external load.

• Methods
• NIOSH
• OCRA
• OWAS
• LIMB

• Methods
• sEMG
• ECG
• HR
• Oxygen consumption
• Subjective assessment

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Assessment of muscle load and fatigue using sEMG
Placement of sEMG electrodes
sEMG registered from four upper limb muscles
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Ovako Working Posture Analysis System
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Packing stand involving repetitive tasks
After intervention
intervention
Before intervention
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Musculoskeletal load assessment on the Bale
Opener work stand
Workers at the Bale Opener work stand reported
pain in wrist and hand. Musculoskeletal load of
upper limb was assessed by means of sEMG.
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Load level of examined muscles during each of
cycle phases
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Results
Analysis of musculoskeletal load of forearm and
hand shows that ?high musculoskeletal load of
hand ?lower, however still high, musculoskeletal
load of forearm ?the highest musculoskeletal load
during tasks of cutting ties and this can cause
upper limb pain ?an important factor in the
development of pain symptoms can be the shape of
steering device, which is the main cause of
musculoskeletal load in phases of steering the
lift
Indicators for ergonomic intervention
? Changes of the shape of steering device by
having it smaller and lighter with shape fitting
the hand and decreasing the push button force. ?
Reduction of musculoskeletal load during cutting
ties can be reached by implementation of scissors
with pneumatic, hydraulic or electric aid.