The purpose of the study was to assess the activity of basketball players (participants in international tournaments) during competitions and in the training process by establishing changes in physiological functions. According to the assessment of the physiological features of basketball players activities during the competitions, changes in the players’ physiological functions during training and competitions have been found out. It has been established that physiological changes in basketball players’ bodies depend on the nature of the play activity and the protection system. The level of oxygen consumption during the game varies from 72.3 to 96.6% of the maximum oxygen consumption with an average of 85.8%. According to the results of the experiment it became clear that the functions of various organs and systems of basketball players develop during the competitions. Therefore, it is necessary to pay great attention to development of both aerobic and anaerobic qualities of athletes in the course of training, in particular of anaerobic glycolytic the speed endurance depends on. The change of protection systems during the game significantly influences aerobic and anaerobic metabolism indicators. The presented empirical results of the research carried out allow us to conclude that the energy supply of sports competitions in basketball is aerobicanaerobic in nature with high proportion of glycolysis. In general, physiological changes in basketball players’ bodies depend on the nature of the play activity and the protection system.