## 4 Discussion
The different field tests used do not allow us to compare the results of the studies. In a recent study, [PERSON] (2022) [19] did not observe a correlation of performance in the YYIR1/YYIE1 with any anthropometric characteristic at various age and playing levels. Specifically, he studied young football players from U10, U12, and U14 teams as well as adult amateurs and professionals. These results confirm the findings of the present study, where no correlations of anthropometric characteristics with the indices of YYIR1 were found. Regarding the differences in \(\text{VO}_{\text{2 max}}\) between playing positions, no difference was observed. It should be noted that goalkeepers were not included in the study. Similar findings were reported by other studies [24; 25; 26; 39]. However, in an earlier study, it was reported that midfielders had higher \(\text{VO}_{\text{2 max}}\) values than forwards and defenders [22]. Additionally, [PERSON] et al. (2011) [40] reported that midfielders and forwards had higher \(\text{VO}_{\text{2 max}}\) values than goalkeepers and defenders. Furthermore, [PERSON] et al. [39] observed that forwards showed the highest values among all other playing positions. The differences presented in the results of the studies are likely due to the different characteristics of the participants. In professional football, players in midfield positions, as well as positions on the sides, which exhibit the greatest external load during matches [20], tend to show higher \(\text{VO}_{\text{2 max}}\) values [22]. Studies in developmental ages show greater differentiation in their results, possibly because football players have not been influenced by specialized positional coaching. Regarding the variables from the YYIR1 test, no differences were observed between playing positions. In a study conducted on young football players aged U13-U19, it was observed that central defenders had significantly lower performance than central midfielders, wide midfielders, and forwards (but not lower than side defenders). In another study [29] conducted on elite young football players (U15), it was observed that goalkeepers had the lowest \(\text{VO}_{\text{2 max}}\) value and differed from all other playing positions both before and after the competitive period. The findings of the present study are consistent with those of the above study (if goalkeepers are not included). In the present study, no differences were observed between playing positions in any of the anthropometric characteristics. [PERSON] et al. (2021) [41] observed that goalkeepers were taller, heavier, and had a higher percentage of body fat compared to players in other positions. Wingers had the lowest percentage of body fat, and central defenders had the least lean body mass among all positions. Similar results are reported by other studies where only goalkeepers differed in body mass and height [39; 42], while forwards showed the lowest percentage of body fat [39]. [PERSON] et al. (2022) [29] in their recent study observed that central defenders and forwards were heavier compared to central midfielders. Additionally, central and side midfielders were shorter compared to those in other playing positions. The lack of differences in the anthropometric characteristics of football players in different playing positions may be due to the criteria used to select the players. Specifically, these players were chosen for the team, and the selection criteria may lead to a specific profile of anthropometric characteristics. Another reason may be the lack of specialized training for specific positions, which would result in specific adaptations in the players' bodies. The present study has some limitations. The sample of the study may be considered limited, and the results cannot be generalized. Additionally, the small sample resulted in a small number of football players in each playing position. Additionally, the participating football players were members of the same team, limiting the representativeness of football players of this age group.