Preface

Optimal health and a high level of fitness have been long recognized as a key to the future of any human population. Concern for the development of future generations has been a central theme in all civilizations, not only in those well developed, but also in primitive ones. However, even under positive conditions of problems can appear: provision of a favourable environment with an ample diet, adequate education and health care is no guarantee that appropriate level of physical fitness, health status and its prognosis in children and adolescents will be achieved. The increasing level of economic conditions and the improvement of nutrition have been contributing not only to an accelerated growth and development, but also to disproportional development of body composition, which concern the whole population. This has manifested especially by an increasing ratio of adipose tissue in the organism, which has affected all age categories including the preschool one; often without more apparent changes of total body weight and body mass index - BMI (“hidden obesity”). Nutritional intake, both from the point of view of energy content as well as the composition of the diet (especially the ratio of saturated fats and simple sugars) has not corresponded to the actual needs of the organism - mainly from the point of view of reduced energy expenditure resulting from the impact of physical inactivity (WHO 2010a,b,c). This concerns already children of early age, who are characterized by highest level of spontaneous physical activity, and therefore reduced possibility to move, play and exercise is mostly unnatural at this age. This mostly continues during following years and has undesirable results. Secular trend of increasing adiposity along with the reduction of functional capacity and motor abilities was found since youngest age, and runs parallel with increased health risks which have started to appear already during this period of growth. With regard to health problems resulting from a generally enhanced adiposity and increasing prevalence of obesity, this situation is harmful at any age including school age and adolescence, especially when considering possible delayed health effects in adult and advanced age. Introduction of an appropriate régime of not only nutrition, but also of physical activity is indispensable, starting with the very beginning of life. In this respect, an approach based on proper evaluation of the individual including genetic factors should be also implemented as all humans are special from all points of view – also as nutritional and motor individualities (Pařízková 1998, 2008, 2010, 2011). More recently also the interrelationships between nutrition - its energy content and composition on the one hand, and energy expenditure resulting from physical activity level on the other one have been considered and analyzed in greater extent and detail. However, the effect of physical activity (PA) as a significant metabolic, nutritional, hormonal, psychological etc stimulus has not always been - as has been much more the effect of others like diet – more exactly defined, assessed and analyzed with regard to its character, intensity, frequency and regularity along satifactorily long periods of human growth, and also with special regard to not only genetic, but also epigenetic factors influencing the organism since early life. The last mentioned factor – the composition of early diet concerning e.g. proteins – was mentioned above. This monograph is aimed, among others, to contribute to this problem and with an effort for a more complex approach. However, it has been too difficult to summarize more aspects in their mutual relationships, and also according to the present state of art, as this fragmented research is a permanently developing story. Too many new studies and reviews have been appearing during recent years until present which have not been homogenously aimed and planned, executed, elaborated and interpreted, followed up in comparable groups with regard to age span, gender, degree of sexual maturation, dietary intake, social and cultural status and many others – so consented conclusions could have been hardly achieved. But hopefully, some of the presented information could at least partly contribute to further developement of this important topic.