Análise dos esforços de alta intensidade de jogadores de futebol profissional / Analysis of high intensity efforts of professional soccer players

AUTOR(ES)
DATA DE PUBLICAÇÃO

2010

RESUMO

The aim of this work is to characterize the high intensity efforts performed by soccer players during official games. For these, nine games of the first division Brazilian championship game was recorded by four stationary digital video cameras, with acquisition frequency of 7.5 and 30 Hz, positioned in the highest points of the stadium. Players trajectories during the whole game were obtained through an automatic tracking method with Dvideo (Figueroa et al. 2006). These data were reconstructed in 2D and smoothed using a third order Butterworth low-pass filter with cutoff frequency of 0.375 Hz, available in Matlab® software. In this study 107 players that played the entire game were analyzed, excluding goalkeepers. The players were divided in five positions that were: central defenders (n=27), full backs (n=25), central midfielders (n=18), wide midfielders (n=17), attackers (n=20). The curves of velocity were obtained by numerical derivation from the data of the smoothed trajectories. In the present study the sprint was divided in two phases: the beginning of the phase 1 was defined as the first local minimum before a value of 6.4 m/s and the final as the instant that velocity was higher from 6.4 m/s. The beginning of the phase 2 was defined as the instant that velocity was higher from 6.4 m/s and the final the instant the velocity lower them 6.4 m/s. From the new definition, variables of the sprints were calculated to characterize them. The results showed that the numbers of sprints, sprints distance covered in the phase 1 and 2, sprints duration in the phase 1 and 2, initial velocity, peak velocity, time between each sprint and percentage of time walking after high intensity efforts were respectively, 32±12 sprints, 8±5 m, 12±9 m, 2±1 s, 1,6±1 s, 2±1.5 m/s, 7±1 m/s e 158±176 s. Comparison between first and second half, the number of high intensity efforts performed by the players showed a significant drop from first to second half, and the time between each high intensity efforts was a significant increase between the first and second half. Comparing the five positions of the players, the results showed that the distance covered and duration of each high intensity efforts during in the phase 2, the full backs covered a great distance and take longer time to make a sprint that central defenders and attackers. Already the percentage of time walking after high intensity efforts the central defenders and attackers spend more time walking than full backs, central midfielders and wide midfielders. The full backs, attackers and wide midfielders had a time between each high intensity efforts lower compared to the central defenders and central midfielders. The time between each high intensity efforts and the percentage of time walking after high intensity high intensity efforts at the end of the first half and at the end of the second half has significant differences with the first 15 minutes of the first and second time. It is possible to conclude that incorporating the acceleration phase allowed a better characterization of high intensity efforts of soccer players. For now on the physical trainers have more information about the effort required during a high intensity run

ASSUNTO(S)

futebol sprint rastreamento automático biomecânica soccer sprint automatic tracking biomechanics

Documentos Relacionados