2.2. Physical Exercise Test
A multistage 20 m shuttle run test (Beep Test) [The maximal multistage 20 m shuttle run test was controlled using a Lenovo ThinkPad X1 Yoga laptop computer, wired to Harbeth Super HL5 Plus speakers. The Beep Test was supervised by the team trainer (UEFA Pro Qualifications) using the program recommended by the Polish Football Association (PZPN) as a monitoring tool for examining changes in the level of cardio-respiratory fitness in all age categories of the football players.