Long trainings promote perfection of the regulatory mechanisms, that is characterized by an increase of cholinergic effects on the cardiovascular system of children. An optimal ratio of sympathetic and parasympathetic effects is typical of swimmer girls of different age with high level of working capacity in rest, that influences the adequate adaptation of the cardiovascular system to physical exercises. There are limits of adaptibility of the cardiovascular system of swimmer girls which is determined by informative indices of histogram. As influenced by physical exercises the favourable, incomplete favourable and unfavourable directions of the cardiovascular system shifts in swimmer girls are observed. Essential individual variations of the pattern of the functional changes in the cardiovascular system confirm the necessity to organize the training process allowing for the individual peculiarities of the development of children and adolescents.