Ergonomics guidelines for the optimization of musculoskeletal workload
ISO/TS 20646:2014 provides information and guidelines to properly utilize various ergonomics standards concerning the factors related to musculoskeletal workload (MSWL), and helps develop activities to reduce or optimize MSWL in workplaces and non-professional activities, in an effective and efficient manner. The activities are intended to be based on a risk assessment. ISO/TS 20646:2014 is intended primarily for employers, ergonomics and occupational health-related staff and workers in enterprises, and workers. Prevention of MSWL is not always a matter of reducing the load. The approach to reducing MSWL also involves assessing the work environment and organization as a system to identify how changes can help to safely manage MSWL. Although it provides ideas of effective and efficient measures to reduce or optimize MSWL, ISO/TS 20646:2014 does not certify the complete prevention of health problems caused by MSWL.
Lignes directrices ergonomiques pour l'amélioration des charges de travail musculo-squelettiques
Standards Content (Sample)
Ergonomics guidelines for the
optimization of musculoskeletal
Lignes directrices ergonomiques pour l’amélioration des charges de
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1 Scope . 1
2 Terms and definitions . 1
3 General guiding principles . 2
3.1 Basic principles to improve MSWL . 2
3.2 Basic framework and responsibilities of MSWL-improvement activities . 2
3.3 Processes for MSWL risk assessment including implementation of risk reduction activity 3
Annex A (informative) Schedule form for principles, plan, and implementation .7
Annex B (informative) Checklist for hazard identification concerning musculoskeletal workload .8
Annex C (informative) Action-oriented checklist .12
Annex D (informative) Questionnaire for monitoring the effects of risk reduction measures
concerning musculoskeletal workloads .15
Annex E (informative) Evaluation form for the risk reduction measures .17
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ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
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described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2. www.iso.org/directives
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of any
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For an explanation on the meaning of ISO specific terms and expressions related to conformity
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Barriers to Trade (TBT) see the following URL: Foreword - Supplementary information
The committee responsible for this document is ISO/TC 159, Ergonomics, Subcommittee SC 3,
Anthropometry and biomechanics.
ISO/TS 20646 cancels and replaces ISO/TS 20646-1:2004, of which it constitutes a technical revision.
This corrected version of ISO/TS 20646:2014 incorporates the following corrections: the title has been
changed from Ergonomic procedures for the improvement of local muscular workloads to Ergonomics
guidelines for the optimization of musculoskeletal workload.
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The onset of work-related musculoskeletal disorders, such as low back pain and upper and lower limb
disorders, is becoming a great ergonomic concern in both industrialised and industrialising countries.
The high incidence of work-related musculoskeletal disorders is an important problem to be solved not
only to improve workers’ health and the quality of working life, but also to improve productivity.
In order to solve the problem of work-related musculoskeletal disorders, it is important to work out
primary preventive measures, through improving working conditions and providing adequate health
guidance and training, as well as to establish measures for secondary prevention, treatment, and
reassignment of the workers after a long sick leave.
Above all, the establishment of primary preventive measures, mainly measures to improve
musculoskeletal workloads (MSWL), are considered to be the most cost-effective solution and improve
the quality of working life. Various activities to improve MSWL have already been promoted. In addition,
regarding ISO/TC 159/SC 3, new standards are developed to improve working conditions relating to the
factors causing MSWL. However, in order to improve MSWL, it is indispensable to take a comprehensive
work-related perspective and find a solution, in consideration of the aforementioned factors.
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TECHNICAL SPECIFICATION ISO/TS 20646:2014(E)
Ergonomics guidelines for the optimization of
This Technical Specification provides information and guidelines to properly utilize various ergonomics
standards concerning the factors related to musculoskeletal workload (MSWL), and helps develop
activities to reduce or optimize MSWL in workplaces and non-professional activities, in an effective
and efficient manner. The activities are intended to be based on a risk assessment. This Technical
Specification is intended primarily for employers, ergonomics and occupational health-related staff and
workers in enterprises, and workers. Prevention of MSWL is not always a matter of reducing the load.
The approach to reducing MSWL also involves assessing the work environment and organization as a
system to identify how changes can help to safely manage MSWL. Although this Technical Specification
provides ideas of effective and efficient measures to reduce or optimize MSWL, it does not certify the
complete prevention of health problems caused by MSWL.
2 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
loads on the musculoskeletal system required for working motions, maintaining working postures, and
physical injury or damage to health
[SOURCE: ISO 12100]
potential source of harm
[SOURCE: ISO 12100]
combination of the probability of occurrence of harm and the severity of that harm
[SOURCE: ISO 12100]
overall process comprising a risk analysis and risk evaluation
[SOURCE: ISO 12100]
combination of the specification of work description, hazard identification, and risk estimation
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defining likely severity of harm and probability of its occurrence
[SOURCE: ISO 12100]
judgment on the basis of successive risk analysis of whether the risk reduction objectives have been
[SOURCE: ISO 12100]
volume of space allocated to one or more persons in the work system to complete a work task
[SOURCE: ISO 9241-5]
combination of work equipment for a particular person in a work space
Note 1 to entry: It is possible that several persons share a particular workstation, or that several persons alternate
between several workstations within any period of time (i.e. hourly, daily, weekly basis).
[SOURCE: ISO 11064-2]
3 General guiding principles
3.1 Basic principles to improve MSWL
Management should clarify in writing existing and predicted MSWL and possible health- and
productivity-related problems, and publish improvement goals and targets, a basic schedule to achieve
the targets, and the organization to implement the improvement (see Annex A).
3.2 Basic framework and responsibilities of MSWL-improvement activities
As organizations draft, implement, and assess MSWL-reduction plans, organizations at the enterprise
level and department level, and advisory organizations, should develop activities in a collaborative
manner. The participation of workers and/or their representatives is essential.
3.2.2 Enterprise level
A structure to manage MSWL should be established at the enterprise level, either as part of existing
management systems for work design or occupational safety and health, or as a specifically designated
project activity. The owner or executive director with overall management authority should be
responsible for the establishment and the conduct of this organization.
3.2.3 Department level
This refers to an organization within an individual department, for which the departmental manager
should be responsible. Its function is to draft, implement, and assess the improvement plans for the
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3.2.4 Advisory level
This refers to an organization offering advice concerning the validity of drafting, implementation, and
assessment of improvement plans. The organization can be established inside or outside the enterprise.
3.3 Processes for MSWL risk assessment including implementation of risk reduction
An MSWL risk reduction plan should not be limited to a few specific factors causing loads. It should be
based on MSWL risk assessment in the workplace. On the basis of comprehensive risk assessment using
this multi-factorial analysis, specific action targets should be set to eliminate or reduce unacceptable
risks. Basic processes in achieving this target(s) are given in 3.3.1 to 3.3.4 (see ISO 12100).
3.3.2 Risk assessment
To study necessary activities to reduce the risks of MSWL, risk assessment should be implemented. This
includes a risk analysis with work description, hazard identification, and risk estimation as well as a
risk evaluation. Priority risks should be addressed immediately, so as to reduce risks or reinforce the
126.96.36.199 Specification of work situation
To study the characteristics of work, the following items should be described:
a) production process, contents of work, and tasks to be performed at the workplace;
b) statistics on occupational accidents, incidence of work-related diseases and other diseases, sick
c) work organization and shift systems;
d) work hours per day, week, month, or year;
e) operating time per day, continuous operating time, and a rest system;
f) characteristics of the workers, such as body size, muscle strength, history of injuries and diseases
affecting work, work experience, vocational education and training, and age;
g) characteristics of the work, such as static workload, physical inactivity, repetitive work, and manual
188.8.131.52 Hazard identification
The following factors are the main hazards for MSWL (see Annex B). They are divided into six sections.
184.108.40.206.1 Checklist section 1 — Work hours and work concentrations
a) long working shifts more than 8 h a day
b) frequent and long overtime work
c) long continuous operating time
d) insufficient rest breaks
e) insufficient days off
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f) uneven work concentrations in a day, week, month, or year
g) uneven work concentrations between the workers
h) insufficient rest between shifts (less than 11 h)
220.127.116.11.2 Checklist section 2 — Type of work
a) lifting and carrying heavy objects (see ISO 11228-1)
b) work requiring great force
c) high pushing and pulling forces (see ISO 11228-2)
d) high repetitive work (see ISO 11228-3)
e) work requiring frequent finger, hand, or arm motions (see ISO 11228-3)
f) using hand-arm vibrating tools during the work
g) work using vehicles transmitting whole-body vibration
h) intensive work with a keyboard or other data entry devices
i) precision work
j) high visual requirements
18.104.22.168.3 Checklist section 3 — Postures and motions
a) awkward postures and motions (see ISO 11226)
b) continuous and/or highly frequent change in joint positions (see ISO 11228-3)
c) long-duration constrained posture (see ISO 11226)
d) long-duration and/or long-distance walking (horizontal as well as on an inclined surface)
e) frequent stair climbing
f) prolonged sedentary/standing work
22.214.171.124.4 Checklist section 4 — Influencing work space and task factors
a) inadequate work space forcing an awkward posture or limited movement
NOTE For consistency references, see ISO 11226.
b) layout of the workstation forcing excessive movement or awkward postures
c) inadequate height and dimensions of the work surface
d) handling work objects above the shoulder or below the knee
e) work space forcing the worker to maintain the same working posture
f) work objects which are heavy and/or require high physical force
g) work objects which are difficult to hold or slippery
h) cold/hot work environment and/or objects handled
i) high contact stress or local pressure acting on the body
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126.96.36.199.5 Checklist section 5 — Influencing psychosocial factors
a) mental overload or underload
b) time pressure and high demands
c) work-related stress
d) low job satisfaction
e) lack of autonomy (low influence, low control)
f) social support
188.8.131.52.6 Checklist section 6 — Influencing environmental factors
a) slippery and/or uneven floor surface
b) whole-body vibration (see ISO 2631)/hand-arm vibration (see ISO 5349)
c) hot and cold work environment
d) poor visual conditions (e.g. insufficient lighting)
3.3.3 Risk estimation
Risk estimation should take into account the severity of the hazard(s) and probability of its occurrence
and the number of workers who will be affected.
3.3.4 Risk reduction measures
184.108.40.206 Specifying risk reduction measures followed by a small trial of the improvement
To study the importance of risk factors and evaluate possible preventive measures for risk reduction,
the following factors should be considered:
— results of the risk analysis;
— ease of implementation of the risk reduction plan;
— effect of the improvement after reducing the risk;
— number of workers who will benefit;
— cost-efficiency of the plan.
Use of an action-oriented checklist is recommended to perform risk analysis, and to get hints for
improvement (see Annex C). The recommended procedure for using the checklist is as follows.
a) Organize a group to implement a checklist practice. In the group, the owner or executive director
with management authority, managers and workers of concerned sections, and occupational health
and safety personnel should be involved.
b) Define the workplace to be checked.
c) Fill out the checklist individually.
d) Organize small group discussions on the risk factors found at the workplace and the factors with
priority of improvement.
e) Make an action plan to reduce risks for MSWL at the workplace.
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f) Carry out a small trial to ensure the effect of the improvement before implementing the improvement
on a large scale.
220.127.116.11 Implementation of risk reduction measures and monitoring the effectiveness of the
To check the effectiveness or insufficiency of the risk reduction measures, scheduled monitoring of the
MSWL level and health problems of the workers should be provided. It is recommended that the subjective
estimation of MSWL levels both before and after the implementation is checked (see Annex D). Statistics
of sick leave relating to MSWL, productivity, and incidence of musculoskeletal diseases are also useful
to evaluate the effectiveness of the risk reduction measures.
18.104.22.168 Risk evaluation and drafting of new risk reduction plans
To check the effectiveness of risk reduction measures and to find any new or remaining problems,
periodic evaluations should be carried out. Evaluations should be performed if changes are made to the
product manufactured, the process used, or the workstation, or if increased incidence and complaints
are noticed (see Annex E).
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Schedule form for principles, plan, and implementation
(Enter the management’s statement of commitment to improvement of work conditions here.)
A.2 Motivation for improvement
[Describe the present state of the workplace. Specifically, state the overview of the characteristics
of works at the workplace, and describe the following points concerning MSWL so that readers can
understand the reason why work conditions improvement should be promoted: “possible hazards that
work entails”, “foreseeable problems in the context of health management and productivity”, “severity
of problems and extent of their possibilities”, and “the present state of foreseeable problems (including
conditions for the onset of the disorder and productivity)”.]
A.3 Improvement target
(Describe the work conditions that should be improved and to what the goal will be, with deadlines
A.4 Implementation schedule of improvement projects
(Clarify the schedule of the project, mainly the following actions
a) Identify hazards concerning musculoskeletal workload.
b) Risk assessment and selection of improvement plan.
c) Drafting of improvement plan.
d) Implementation of improvement plan.
e) Measurement of consequences of implementation of improvement plans.
f) Records of improvement actions taken and in-house announcement.)
(Enter the budget amount allocated by the management for this project.)
A.6 Department/section responsible for the project
(Enter the department/section responsible for the project.)
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