Relative age effects and the youth-to-senior transition in Italian soccer: the underdog hypothesis versus knock-on effects of relative age

Youth-to-senior transition in women’s and girls’ football: Towards a better understanding of relative age effects and gender-specific considerations

“…Of these female-only studies, the prognostic validity of physical during adolescence (i.e., 20 m sprint or dribbling ability) to predict youth [ 8 ] or senior success [ 7 ] was shown in German female football. Nevertheless, the application of early predictors is often flawed and subject to biases, which limits academies’ success in identifying correctly future successful and talented players [ 9 – 14 ].…”

“…In this regard, a study on the male Italian football talent system identified as, independent from playing position, 10–20% of players selected youth national teams (i.e., Under 16, 17, 18, or 19) were subsequently selected in senior national team [ 16 ]. This suggests that international youth experience may not be a prerequisite for an international career in adulthood [ 14 , 16 ].…”

“…While the RAE is well documented in male football, whereby a consistent and pervasive RAE exists, especially in the youth age groups [ 14 , 18 , 19 ], its presence remains inconclusive in females [ 17 , 21 ]. More specifically, the RAE seems mixed depending on contextual factors such as sociocultural context (i.e., depth of competition, attraction level and country-specific differences) [ 22 ], age groups [ 20 ], competition levels [ 23 ], playing positions [ 20 ], and historical moment [ 24 ].…”

“…Although the RAE impacts the selection of future football players, with the potential cost of missing this talent may be difficult to calculate accurately (Kelly et al, 2020), some studies provide evidence of a possible long-term advantage of relatively younger players during their senior career. This scenario, referred to as the ‘underdog hypothesis’ [ 31 , 32 ], suggests that players born towards the end of the selection date have a greater opportunity to successfully transition to senior level once selected into talent pathways [ 14 , 33 ]. In this regard, recent studies showed that the probability of achieving a professional contract was about four times higher for English relatively younger players [ 33 ], as well as about three and four times the probability of competing in the Italian Senior National Team or a UEFA European Champions and/or FIFA World Championship respectively [ 14 ].…”

“…This scenario, referred to as the ‘underdog hypothesis’ [ 31 , 32 ], suggests that players born towards the end of the selection date have a greater opportunity to successfully transition to senior level once selected into talent pathways [ 14 , 33 ]. In this regard, recent studies showed that the probability of achieving a professional contract was about four times higher for English relatively younger players [ 33 ], as well as about three and four times the probability of competing in the Italian Senior National Team or a UEFA European Champions and/or FIFA World Championship respectively [ 14 ]. Interestingly, in the Italian context, the RAE magnitude was smaller for players that successfully transitioned from youth to senior national teams than those who failed to transition [ 16 ].…”