Results of health studies on children and adolescents show clearly their physical and psychosocial impairments. Stress, social isolation, familial strains, false diet behaviour and above all a lack of activity play a major role as risk factors for the health of children. Closely connected to the last-named risk factor, lack of activity, is the physical performance or fitness of children and adolescents. The findings on physical performance of children and adolescents are still heterogeneous. This situation is primarily due to the difficulties in comparing the data because of the application of different test procedures as well as the different determinations of critical values for "noticeable problems" - thus a clear agreement about what test achievements are good or not good is hardly possible. Despite these methodological difficulties one can note that literature reviews from Bös, Dordel and Gaschler as well as different studies support the assumption that the physical performance of children and adolescents has decreased in the last two decades. From 1975 until 2000 the difference in ability amounts to about 10%, whereas the regression in ability can be seen the plainest in course endurance and flexibility, for both boys and girls. In fact physical performance and physical fitness are basic health resources. Through the fortification of the cardiovascular system, stabilisation of the retaining and motion apparatus and the economization of motion executions, physical fitness is an important protection against metabolic risks, psychosomatic disorders and diseases as well as accidents.