Effects of playing football matches with two balls on spatial exploration

Objective: This study compared young footballers' spatial exploration index (SEI) overall and one by one during simulated matches played with one or two balls.

Methods: Forty-four association football players from U14 and U16 teams of the same club played two 60-minute matches with all the official game rules and regulatory conditions. The unique difference was that one match was played with a single ball and the other with two balls simultaneously. Positional data were gathered during matches using a Global Positioning System (GPS) to assess each footballer's SEI central tendency and approximate entropy (ApEn) measures.

Results: The average SEI of both U14 (p = .01; η2 = .066, medium) and U16 (p < .001; η2 = .187, large) players was lower, and its ApEn higher (U14: p < .001, η2 = .014, small; U16: p < .001, η2 = .035, small), during the two-ball match in comparison to the standard one-ball match. The graphical representation shows how their relative positioning changed between matches, breaking team formation in two during the two-ball condition. From an individual perspective, the second ball affected defenders mainly. Most of them reduced their intervention area, acted more unpredictably within this, and got closer to their target compared with the standard one-ball match.

Conclusions: Adding an extra ball led young footballers to explore less space more unpredictably, especially defenders. So, a one-by-one analysis may assist coaches in evaluating each player's tactical response to football training.