The purpose of this study was to ascertain the perceived exertion by soccer players (on a 10-point scale) during brief side-games during the training process. A total of 14 amateurs took part in 27 brief side-games over nine training sessions that altered the order, spatial orientation andnumber of players per team. The variance was analysed through the General Linear Model (GLM) with these three facets and the accuracy of generalization was estimated. Furthermore, an ANOVA analysis was performed to determine the degree of significance of the differences between variables. The results indicate that both the change in spatial orientation and number of players per team affect the perception of the task's intensity, improving the players' perception when the space is not oriented and the number of players is reduced, while the order facet did not provide the model with any variability. We conclude that the inclusion and modification of the orientation and number of players per team variables allow coaches to optimize the training process in soccer.