“…Although at the beginning, this type of aggrupation was used with the objective of trying to prevent differences in the formation of the athletes (González, 2007) through an appropriate development and fair competition with equal opportunities (Musch & Grondin, 2001;Gutiérrez, 2013), but what it really provokes is the existence of differences in age and therefore potentially differences in maturation and experience among the members of a same category (Gutiérrez, 2013). Unfortunately, studies confirm that the distribution of athletes to groups by age provokes differences among the athletes at physical (Delorme & Raspaud, 2009), cognitive (Bisanz, Morrison, & Dunn, 1995), motivational (Dixon, Horton, & Weir, 2011) and existential levels (Musch & Grondin, 2001). For this reason, the players born in the first months of the year come to have a kind of advantage over those born later in the competition year (Carling, Le Gall, Reilly, & Williams, 2009;González, 2007).…”