Assessment of working positions and movements

March 1998

According to working environment legislation, working using unsuitable positions or movements must be avoided.

Movement and variations of working positions are necessary for maintaining the body’s function level. On the other hand, unsuitable working positions and movements present a risk of acute injury and risk of cumulative wear.

This WEA Guideline provides detailed information about working positions and movements

• How the risk of unsuitable working positions and movements are assessed
• How unsuitable working positions and movements can be prevented or avoided.

The WEA Guideline contains guidance on assessing working positions and movements. The WEA Guideline has been prepared on the basis of existing knowledge about working positions and movements, and reflects the Danish Working Environment Authority’s assessment practice. There is still not sufficient knowledge to be able to determine more precise guidelines, for example, about how long can be spent working in unsuitable working positions without risking injury.

According to working environment legislation, it is the employer’s responsibility to ensure that the risks related to unsuitable working positions and movements are assessed and that the work, based on this assessment, is planned, organised and carried out so that there is no danger of injury or danger to health.

Risk of industrial accidents resulting from unsuitable working positions or movements

Lower-back difficulties, which are especially due to bending the back forward, twisting, bending sideways or bending backward. This is especially risky if the position is maintained for a long time, when the movement is repeated often or when lifting at the same time.

Back of the neck and shoulder difficulties, which are especially related to working with raised arms, stiff position of the head or when work requires an especially high visual acuity or demands on precision.

Hand and arm movement difficulties, which are especially related to frequent, repeated movements, great effort or movements to outer positions of the elbow and hand.

Knee difficulties, which occur especially in people who work on their knees

Hip difficulties, which especially occur in people who work while standing/walking.

Assessment of working positions and movements

The assessment includes working positions, which may be:

• standing/walking
• sitting
• squatting/kneeling/on knees
• lying down

as well as movements of the back of the neck, the back, the arms, and the legs or limitations of these movements due to working in restricted space conditions.

The assessment includes the risk of injury

• where work is done for a long time in stressful working positions or using stressful movements.
• if the work is dynamic or static, cf. below.
• if the work is monotonous; that is, if one or more body parts repeat the same movements for a long time.
• if the work is fixed; for example, assembly-line work or precision work that makes it difficult to vary the working position.
• if heavy work is carried out at the same time; for example, pulling, pushing, lifting of loads or using heavy manual tools.
• if fast tempos or high precision are required while working.
• how much one has to bend and/or twist the back, back of the neck, hips and knees.
• how far arms have to be raised, especially how far arms are raised forward, outward or backward at the shoulder joint, as well as whether work is done with the hands at elbow, shoulder or head level. Attention must also be paid to how much elbows and wrists are bent and twisted.
• how gravity affects the body in the working position; for example, whether work is done while bending the back where the weight of the upper body in itself causes straining of the back.
• whether personal protective equipment restricts or limits working positions or movements.

Static work causes muscles to tighten, even though only small or no movements are made; for example, when working with IT keyboards and mice. Static work limits oxygen supply to muscles, resulting in rapid tiring of muscles with the risk of injury.

Even with limited application of force, static work may cause muscle and joint problems. Dynamic work means that working with muscles done with movements; for example, using leg muscles dynamically while walking and running. Dynamic work means that muscles do not tire as easily because the supply of oxygen is not limited.

Many work operations involve static work involving muscle groups that are not intended for static work; for example, small muscles in the neck, shoulders and arms.

Guidelines for using the assessment model

An attachment to this WEA Guideline includes a reproduction of a model to be used for assessing working positions and movements. The model is based on one of the four positions that are used when carrying out a specific work task.

It is crucial for the assessment to determine how often and how much time is spent in the working positions and using the movements.

The work task is then classified according to whether it is in the red, yellow or green area.

In the red area, the strain is not acceptable. There is a risk of injury for much of the active working population who spend a long time in these working positions and with these movements during daily work. The risk is greatest for positions and movements in or close to the outer positions of the joints.

Note, however, that there is no working position that would be natural to assume and which involves no external strain or risk of injury, results in a risk of injury, if it is only assumed for a short time.

In the yellow area, the work task is assessed in more detail. Assessments which determine a risk of health injuries in the yellow area typically look at duration, degree of fixed position and strain combinations; for example, lifting in overburdening working positions.

It may be necessary for an assessment in the yellow area to be carried out by specialists in the field.

In the green area, work is done using acceptable positions and movements. A more detailed assessment in terms of the person and the work strain is only made if an employee experiences discomfort from the work.

Prevention of industrial injuries

Stressful working positions and movements are often related to unsuitable preparation of work, poorly arranged working areas, machines or equipment, poor space conditions or because the work can only be carried out at uncomfortable work heights or in small spaces. The longer and more often work is done in stressful working positions, the greater the risk is of musculoskeletal disorders.

Preventive measures therefore consist of better preparation of the work and better arranged working areas, machines and equipment.

The work should be prepared in a variety of ways so that work is not done for a long time in the same working positions or using the same movements. Also, major changes to the organisation of the work, such as job extensions, job enrichments or self-managing groups may contribute to increasing the variation of the individual’s working positions and movements.

If it is not possible to ensure sufficient variation of working positions and movements, and the work, therefore, may result in a considerable risk to safety or health, the individual must have suitable breaks so that the muscles and circulation can recover.

As a general rule, the individual’s place of work must be adjusted to the person doing the work, regardless of the size and proportions of the person.

If, due to the nature of the work, the work must be done in the same place for long periods of time, it may be possible to vary between sitting and standing work by having sufficiently flexible equipment, for example by adjusting the table height for sitting and standing work and for different work operations.

Jens Andersen