Man develops during phylogenesis and ontogenesis as an active creature and his most striking external manifestations include physical activity. From this ensue efforts to investigate the human organism with regard to its functional diagnosis mainly during activity, in relation to the level of that physical activity. The amount and qualitative aspect of physical activity is subject to some laws associated with the developmental stage, type of higher nervous activity, health, nutritional status, external environment inc!. social position, profession, hobbies, etc.; thus it is also one of the important ecological factors. During the period before the onset of technical civilization physical fitness and performance were essential prerequisites for survival and successful existence. At present and from the aspect of the perspective development of our civilization the importance of physical fitness is pushed into the background; nevertheless adequate physical activity level is even today an important prerequisite for normal function of the organism as a whole.