## 4 Discussion
The running performance decrease observed in this study was likely due to player fatigue and not tactical reasons, as a significant decrease in running speed was observed for all positions in the second half. It should be mentioned that in the present study, there were no measured factors that could affect the running performance of the players such as the ranking of the opposing team (opponent quality), the match outcome, and whether the match was home or away. From the literature review, it appears that the above factors may affect the external load of soccer players. More specifically, there are studies that report that the external load is influenced by the quality of the opponent [36; 37; 38], by match location [39; 38], and by the match outcome [36; 40; 41]. Therefore, when analyzing the results, we should be cautious as contextual factors can influence them. In the present study, six home and six away matches were observed, while the random choice of the matches observed ensures the existence of all categories of the above contextual factors in the study. The comparison between the two halves showed that CM and SM reduced the TD in the second half, while CD and F showed a tendency to decrease. In a previous study by [PERSON] et al. (2016) [17], it was observed that all positions reduced TD in the second half and the distance covered at speeds greater than 13 km/h. A decline in running performance in the second half has also been reported in other recent studies [4]. Additionally, the performance of SD decreased in accelerations (Acc2, Acc3) and decelerations (Dec2). Furthermore, CM reduced the number of Acc2 and Dec2, as well as Dec3 in the second half. Finally, SM reduced the number of very intense accelerations and decelerations (Acc3, Dec3). A decrease in the number of accelerations and decelerations in the second half was also mentioned in recent studies [42]. The playing positions can influence this variable. In certain playing positions, there is more space for players to accelerate, so usually the wide players show more and more intense decelerations [42; 43], while CD players do not exhibit many intense accelerations/decelerations. TRIMP\({}_{\text{Edw}}\) decreased in the second half for CM and F, while it decreased in SM without being a significant change. The %HRmax decreased for all playing positions in the second half. [PERSON] et al. (2016) [17] observed that the internal load index they used decreased for all playing positions in the second half, while %HRmax decreased for SD and F.  
In soccer, over the last few decades, there has been a recording of the external load that soccer players experience during a match in order to create the profile of the physical demands of each playing position. Analyzing these data helps tailor training regimens to match the specific physiological demands of the sport, ensuring that players develop the necessary fitness levels and skills required for peak performance on the field. Understanding external load is pivotal for designing periodized training programs that progressively challenge players' physical capabilities while avoiding overtraining and injury. Conversely, internal load focuses on the physiological and psychological responses of soccer players to external stressors. Heart rate, perceived exertion, and hormonal markers are among the indicators used to gauge internal load. Monitoring internal load provides insights into players' fatigue levels, recovery needs, and overall well-being. Striking a balance between external and internal loads is crucial for optimizing performance and minimizing the risk of injuries. Coaches aim to manage training intensity and volume effectively, ensuring that players are adequately challenged while allowing sufficient recovery to enhance adaptation. Recognizing the interplay between external and internal loads is fundamental for developing a holistic approach to soccer player development and performance optimization. The study also has some limitations.