ABSTRACT
Analysis of psychological, ergonomics, and economics literature demonstrates that there are four basic characteristics of task or, more precisely, work activity during task performance: physical demands (heavy work), intensity of work, complexity, and difculty of work. It should be noted that, at present, these terms are not precisely dened and very often are being used synonymously. For example, heavy work is considered synonymous with difcult work (Rodgers and Eggleton, 1986, vol. 2). We consider these characteristics to be totally different. In this section, we will describe physical demands and intensity of work and will perform comparative analysis of these concepts.
