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This method of Finnish origin allows to assess the risks of MSD for the trunk and the lower and upper limbs.


The OWAS (Ovako Work Posture Analysis System) method was developed in the late 70 by a Finnish company originally for applications in the construction and steel industries.

Improved in the years 1990, this method allows to assess the risks for the trunk and the lower and upper limbs taking into account both the postures and the necessary force.

The method

The method is to observe a sequence of operations. This sequence was selected by the history we have, by the returns of the operators…

1-Identify all postures

The first step is to identify the different postures that the operator uses to perform his work. Video is probably the best way to do this work.

2-Evaluating postures

For each posture, an evaluation is carried out:

  • of the back position
  • Of the position of the arms
  • The position of the feet
  • Of the effort needed

For each of these elements, the OWAS method allocates a risk score. The score of each of these criteria is indicated in a table intercutting the 220 possible combinations, thus indicating the type of actions required:

  • Type 1 Action: The posture is natural, the efforts acceptable, the situation is therefore normal. There is no need for specific action, it is necessary to maintain the situation as it is.
  • Type 2 Action: The efforts are too important or the posture is uncomfortable, there can be a detrimental effect on the body. In a short period of time, actions should be put in place to improve the situation.
  • Type 3 Action: The situation is even more at risk with regard to efforts and posture. Measures should be put in place as soon as possible.
  • Type 4 Action: The situation is at risk. We need to take action immediately.

3-Identify the percentage of time in each posture

For each posture, we measure the percentage of time which represents on the whole task.

4-Copy the results and present them

The final step is to take stock of the evaluation. For this, we present the table with a summary of all the postures of the task that we have evaluated. This will bring forward the most critical postures that we need to prioritize.


Karhu et al (1981) – Ovako Working Posture Analysis System

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