The cardiovascular system of schoolchildren at the age of 11-15 was studied as affected by systemic of long lasting physical loads of schoolchildren. In the trained children contrary to adults the respiratory arhythmia is observed, that evidences for nonadequacy of the physical load to the functional state of miocardium. In the cardiovascular system of the trained schoolchildren under the effect of constant trainings there occurs a series of functional changes which increase adaptation to physical loads, that is manifested in a decrease of the systolic and diastolic pressure, the lowering of the systolic index and heart rate, and in increase in mechanical and electromechanical systoles, the amplitude of the teeth R and T. The detected changes in the cardiovascular system are due to the value of trained loads and their nonadequacy to the functionfl state of myocardium.