In recent years, there have been several significant transfers of footballers from the Polish Ekstraklasa, with an increasing number of young Polish players attaining values exceeding EUR 10 million. The sale of players assumes paramount importance for clubs' finances, frequently serving as a vital source of revenue, essential for maintaining competitiveness at the league hierarchy. The article aims to investigate the connection between a club's capacity to produce professional-level players and its ability to generate significant transfer revenues. Lech Poznań and Legia Warsaw have outperformed other clubs in terms of the number of players trained who competed at the top professional level worldwide in season 2021/2022, and also in terms of total transfer revenues in the period 2019–2022. The results confirm the significance of investing in the training of young players in football.

In March 2020, most sports competitions in the world were suspended due to the COVID-19 pandemic. Fan demand for information about top athletes could not be fully satisfied traditionally, that is why social media have grown in popularity. This article aims to identify the factors that affect the engagement of sports fans on social media and is based on the example of Instagram. The number of likes, comments as well as the number of likes and comments divided by the number of followers (appropriate engagement rates), were taken into account as engagement indicators. The results clearly show what types of posts generated the most engagement.