The application of observational methods is evaluator dependent, and it is common for professionals working in the field of Occupational Health to apply them without any previous training. This can compromise or invalidate the evaluation results, as professionals can make serious mistakes when applying them without prior training.

to assess whether the reproducibility of the QEC, REBA, RULA and SI methods is influenced by the evaluator's experience and training and to identify whether the evaluator's training modifies the reproducibility of the methods; and to evaluate the evaluators' perception about the use of observational methods in pre and post training.

This is a study of measurement properties. The study population consisted of analyzing 50 workers with different occupations whose work tasks were filmed for analysis by 11 evaluators, with different levels of experience in using the observational methods of the QEC, REBA, RULA, and SI methods used for analysis in the pre-and post-training. The training of evaluators for the application of observational methods was carried out in 4 modules. The total duration of the training including the modules and practical activities was 30 hours.

There was moderate inter-rater reproducibility, both pre-and post-training, regardless of knowledge of the methods. The training effect was low. The impression about the use of the methods when evaluating working conditions showed that, in general, the QEC and RULA method was considered the easiest to understand, interpret and use with only the instructions for use, by the most experienced evaluators, followed by those with more experience. moderate experience, while the inexperienced preferred the QEC and the REBA. The SI is the method considered the most difficult by all evaluators in pre-training. After training, the evaluators somewhat maintained their trends towards the easier pre-training methods, although they improved their impression of the SI, previously considered more difficult.

The conclusion of this study is that the evaluators do not agree with each other. The training of evaluators to use explicit observational methods interferes little with the identification of exposure to biomechanical risk in the occupational environment and has not shown an effect on changing the evaluation of occupational exposure for inexperienced evaluators, with moderate experience and experts.

By evaluating the need and influence of training for the use of observational methods of analysis of biomechanical exposure, we contribute to improving them by knowing the results of measurement properties.