Physical Activity, Fitness and Adiposity During Growth and their Secular Changes in Different Environment

Physical fitness (PF) in children and adolescents has been declining during last decades along with physical activity (PA) level. As shown by numerous studies, the beginning, rate and rapidity of these changes has been different in various parts of the world as related to local environmental, social, economic, cultural, climatic, and other life conditions. Significant relationship of these changes to health status and prognosis was also revealed. The seriousness of this problem has been emphasized especially that it started to appear already at very early periods of life. Studies of children revealed increasing adiposity along with deteriorating motor abilities already in preschool age, when the level of PA is spontaneously highest. This goes along with earlier adiposity rebound (AR), increasing adiposity and decreasing PA level. Preschool period is defined as one of the critical stages of development, when reduction of natural activity can have more serious consequences than later on. In schoolchildren and adolescents adiposity has been also increasing, and functional capacity along with motor abilities decreasing in many coutries; positive consequences of increased PA régimes have been greater due to the possibility for more intense exercise and sport activities. Increased effort for intervention – which should be based on individual somatic and functional evaluation – should start as early as possible.

Keywords: Adiposity, Adolescents, Aerobic power, Body composition (BC), Energy expenditure (EE), Energy intake (EI), Fat-free mass (FFM), Functional capacity, Lean body mass (LBM), Motor abilities, Physical activity (PA), Physical fitness (PF), Preschool children, School children, Secular trends.