Introduction. Soccer players need to acquire high level of technical, tactical, and physical skills to be able to play at professional level. Changing the pitch size (while keeping the same format of play) causes variations in the relative area per player (calculated as the area of the pitch divided by the number of outpitch players involved in the game). This manipulation is one of the main concerns while using small-sided games (SSG), since different relative areas per player for the same format change the players’ responses. Aim of Study. The present study is part of a doctoral thesis, the purpose of which was to investigate the internal and external load in semi-professional soccer players during SSGs with different numerical ratios and pitch dimensions. Material and Methods. The study sample included 16 semi-professional male soccer players, who played random 1v1, 2v2, 3v3 and 4v4 SSG without goalkeepers and with small goals on individual pitches of 1 : 150 m², 1 : 100 m², and 1 : 75 m² areas, respectively, for 8 weeks until the end of the season. GPS monitoring was used to record the elements of the internal and external loads during the whole training session. The level of significance was fixed at p 0.05. Results. The results indicate that training in different dimensions of pitches and with different players’ format has a different effect on the internal and external load of soccer players. Conclusions. Numerical relationships and the player/space ratio affect the physiological responses of soccer players and should be taken into consideration by coaches for the best coaching design of technical, tactical, and physiological elements. The research findings will help coaches to choose the best training methods based on their training goals. Moreover, coaches in semi-professional teams now have consistent information to design and optimize their training time in mixing the technical and physical aspects.