The relevance of the research problem is due to applying various training programs in the modern education system which are supposed to increase teaching efficiency. In-depth study of some subjects at schools, lyceums and gymnasiums which starts in the elementary school quite often leads to tension and failures of adaptation process in innovative institutions that makes it necessary to work out the criteria of this process. This article deals with studying such criteria as dynamics of intellectual working capacity, physical health and physical fitness of the 1-3rd graders influenced by teaching in classes with in-depth study of a foreign language. The methods of the research of this problem are: the method of proof tests, the health index assessment method, testing of physical qualities that make it possible to define the level of intellectual working capacity, physical health and physical fitness of the 1-3rd graders in their dynamics and interrelation with the intensity of the academic load. The criteria of adaptation of primary school pupils to the academic load of the increased intensity have been worked out in the article. It has been proved that the increase in the academic load increases pupils' intellectual working capacity and has no negative effect on physical fitness of the 1-3rd graders, but it increases their disease incidence that indicates a high physiological cost of organism adaptation to a more intensive academic load. The materials of the article can be useful to elementary school teachers and school psychologists in working out and planning training programs involving in-depth study of subjects.