Adding extra balls elicits tactical variability and external load in youth women's football training

This study compares the effects of introducing multiple or different balls in training games on the tactical and physical performance, enjoyment, and perceived competence of young female association football players. Fourteen trained/developmental under-14 players participated in five 3 × 6-min eight-a-side games: normal conditions, and changing the number (two and three simultaneously) and type (tennis and fitball) of balls. Players’ positional data were collected to assess tactical (spatial exploration index, distances to the nearest teammate and to the nearest opponent, and their entropy measures) and physical (total and low-to-moderate, high speed, very high speed, and sprinting distances covered) performances. Participants also rated their perceptions of enjoyment and competence. Tactical and physical variables ( p < .001) and enjoyment ( p < .05) significantly differed across conditions, but not perceived competence. With multiple balls, players explored less (Cohen's d unbiased = −0.96 to −1.04) and played further away from each other (Cohen's d unbiased = 0.48 to 1.10), while playing closer (Cohen's d unbiased = −0.53 to −2.38) with different balls. Using multiple balls also increased the entropy-based metrics of spatial exploration (Cohen's d unbiased = 1.14 to 1.61) and proximity (Cohen's d unbiased = 0.38 to 0.97), the total distance covered (Cohen's d unbiased = 0.54 to 0.80), and the distances covered at the highest speeds (Cohen's d unbiased = 0.39 to 0.74). Enjoyment was higher in normal conditions than in manipulated conditions (Cohen's d unbiased = 0.49 to 0.99). Academy coaches can incorporate additional balls to increase tactical variability and external load in female footballers to support their development, while the outcomes of using different balls depend on their properties.