Аннотация:This article is devoted to methodological issues of decision-making in certain sports in the process of sports training of athletes. The interrelations between various components of athletes’ sports training are revealed and presented in the form of cognitive schemes. Approaches to the description of the process of sports training are formed, summarizing the experience of coaches and sports scientists. On this basis, conceptual models are built that include factors that influence decision-making, such as training conditions and effects. The definition of training effects observed in sports, such as delayed, residual, saturation, plateau, super-compensation, rebound, tolerance, overtraining, is given. A brief overview of mathematical models describing these effects and how they are implemented in the architecture of decision support systems (DSS) is given. The definition of the so-called “paradox of variability of physical activity” is given, when a more variable and diverse training program leads to better results than a monotonous one. The algorithm of decision-making by trainers and the features of using DSS in practice are described in detail.