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Fatigue, as a psychophysiological state, is a normal human condition experienced as a result of mental or physical activity that consumes one's biological resources. In order to relieve its symptoms and to restore human's ability to continue work, a return to a fresh, relaxed state is required. It is usually obtained by an adequate amount of rest and/or sleep, but under the presence of some disadvantageous factors, such as too hot or too cold microclimate, high levels of noise at a workplace, work overload, psychological stress, lack of motivation, and others, e.g., family or health-related problems, this needed amount of rest simply may not fit into a normal 24-hour cycle of activity, resulting in the fatigue built-up. A fatigued worker becomes prone to performance deterioration, loss of concentration, misjudgment of his/her environmental safety, hazardous behaviors, anxiety and sleepiness. Therefore, worker's fatigue management is essential for improving productivity and quality of work, as well as for building worker's satisfaction, motivation and overall wellbeing. To supervise fatigue, appropriate tools for its measurement are required. This paper presents an overview of existing methods of fatigue measurement, including psychological (self-reports and questionnaires), physiological (i.e., changes in various body functions), and performance related (e.g., reaction time, sensory abilities) ones.

The Subjective Overall Workload Assessment (SOWA) is a tool for overall evaluation of workload. It takes into account the work environment, both static and dynamic workload as well as mental workload. The method allows to identify the dimensions and factors having the greatest influence on the workload. Its huge advantage is an internal consistency assessment which lets researchers to eliminate the unreliable subjects. SOWA has been applied as a tool for evaluation of workload until now. The article shows the application of SOWA method as an effectiveness evaluation tool in ergonomic training. About 300 workers participated in the two-part ergonomic training. Each part included an expert talk, a demonstration and training of proper technique of weight lifting and carrying as well as physical exercises. Between both parts of training there was a six-month interval. The SOWA questionnaire was applied before the first part of training and after the second one in order to control its effectiveness. As the conclusion, it was stated that the ergonomic training influences on the overall workload measured by the SOWA method.

This research is focused on determining the relative importances of diverse work dimensions and their attributes in a large company producing transportation vehicles. Fifty four employees from three different departments took part in this examination. They were all males with significant work experience in the current post and overall in the company. The obtained results were investigated both for all of the examined workers as well as individually for a number of various professions. The whole study was conducted within the Subjective Overall Workload Assessment (SOWA) framework and included the analysis of the manual material handling, body posture and movements, work environment, and mental requirements. The applied method allowed for identifying crucial areas in which immediate ergonomic interventions are necessary. Moreover, it was also possible to specify the hierarchy and order of the issues of ergonomic nature that should be addressed in the longer term.