Relative age influence on team composition of Paulista Football Championship in B division

The relative age (RA) is a phenomenon that is present on football world, specifically in young players, given the fact that young that was born in the first months of year has better performance on selection process. However, the same problem is not analyzed in elite football. The aim of this study was to analyze the effect of RA in professional teams of division B Paulista Football Championship. Were analyzed 1.115 players of 39 teams, they were divided by birthdates and they were indicated by semester and trimester, in semester they were divided by: 1 degrees semester in the firstly Day January to the last Day June and 2 degrees semester were 1 degrees Day July to the last Day of December. In trimester were divided by 1 degrees trimester January to March, 2 degrees trimester April to June, 3 degrees trimester July to September, 4 degrees October to December. The statistical analysis was done by Chi-square test for verification percentage differences. The results showed the high percentage athletes was born in the firstly months of year. It was concluded that RA is present in professional football, especially in the sample of this study.