Relative age effect among U14 football players in Portugal: do geographical location, team quality and playing position matter?

ABSTRACT

Background

Relative age effect (RAE) has been found to be particularly pronounced between 13 and 15 years of age in male football. However, the extent to which the phenomenon varies within a country demands a more comprehensive approach.

Purpose

To examine the effects of geographical location (north; centre-north; centre-south; south; islands), team quality (top-ranked; middle-ranked; bottom-ranked) and playing position (goalkeeper; defender; midfielder; forward) on the birthdate distribution (Q1: January–March; Q2: April–June; Q3: July–September; Q4: October–December) of U14 Portuguese players selected for the national inter-association tournament Lopes da Silva.

Methods

A total of 2,693 players (mean age: 14.12 ± 0.38 years), selected by the 22 regional football associations for the last seven editions of the tournament (2013–2019), was included in the sample.

Results

Chi-square analysis showed a small-to-medium RAE in the U14 cohort compared to the general Portuguese male population (p < .01). Furthermore, the multinomial logistic regression model revealed that the probabilities of selecting Q1 players (vs. Q4) differed (p < .01) based on geographical location (increases of 76.3% in the north and 87.3% in the centre-north zone compared to the regional teams from islands) and team quality (increase of 94.6% in top-ranked compared to the bottom-ranked teams). The playing position did not affect the magnitude of RAE.

Conclusion

Our findings confirm that besides being present in U14 Portuguese male football, the magnitude of RAE is influenced by demographic factors. This study also supports the notion that coaching staffs tend to choose players based on attributes associated with chronological age, seeking to achieve short-term competitive outcomes.

KEYWORDS:

• Youth soccer
• adolescence
• talent identification
• selection process
• birthdate

Acknowledgements

The authors would like to express their gratitude to Catarina Martins (Portuguese Football Association), Emanuel Domingos and Hélder Brito (Algarve Football Association), and João Ramos (Vitória Futebol Clube) for their efforts to assemble the missing data of a few players that have participated in the last seven editions of the U14 national inter-association tournament Lopes da Silva. They also thank Eduardo J. Duarte for making all the geographical arrangements displayed in Figure 1.

Data Availability Statement

The dataset generated and analysed during the current study is available from the corresponding author upon reasonable request.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Notes

1. Considering R as Rows and C as Columns, the degrees of freedom for Cramer’s V were always accounted as the smallest number of (R-1) or (C-1) (Gravetter and Wallnau 2013).

Additional information

Funding

No funding is associated with this study.