Perceived quality of fatigue during different occupational tasks - Development of a questionnaire

In occupational work subjective fatigue has often been measured as intensity in one dimension. The aim of the present study was to analyze additional subjective qualities of fatigue. A questionnaire was answered by 705 persons employed in 16 different occupations. They rated the perceived fatigue during a task which they regarded as being typical of their occupation. Ratings of fatigue were made with regard to 95 verbal expressions, using a numerical ll-grade scale. The ratings were subjected to factor analyses, first exploratively then confirmatively. Five factors were extracted and these were named: (I) Lack of energy; (2) Physical exertion; (3) Physical discomfort; (4) Lack of motivation; (5) Sleepiness. The strength of the five factors differed between the occupational groups. The results offer a new qualitative and quantitative description of the physical (the factors Physical exertion and Physical discomfort) and mental (the factors Lack of motivation and Sleepiness) dimensions of perceived fatigue. In addition, one of the factors, Lack of energy, seems to describe a general underlying quality of fatigue. On the basis of these results, a questionnaire was developed, the Swedish Occupational Fatigue Inventory (SOFI), in which each factor is represented by five expressions.