Variability of tactical behavior of futsal teams from different categories.

The aim of the present study was to analyze the time series of a tactical behavior of futsal players from different categories, in the frequency domain. Using an automatic tracking method, trajectories of 258 players (excluding goalkeepers) were obtained, composed of 79 players from the under-15 (U15) category, 86 from the under-18 (U18), and 93 from the professional. We calculated the team spread defined as the Euclidean norm of the distance-between-player vector as function of time. We applied the FFT (Fast Fourier Transformation) method and calculated the median frequency for each time series of spread. The results of mean ± SD of the median frequency of the time series of spread from the first to the second half were significantly different only for the U15 category (first half, 1.04 ± 0.46, second half 1.40 ± 0.34). The frequency values differed significantly between the categories. Youngest categories presented a higher frequency of spread oscillation than the professional category, which reflects the dynamics of the game between attack and defense sequences. Results provide insights about the features of the sport and give basis to proper training interventions for players in each category planning for future transition to the following category.