Quantification of the Relative Age Effect in Three Indices of Physical Performance

Abstract

Abstract.The relative age effect (RAE) describes the relationship between an individual's birth month and their level of attainment in sports. There is a clustering of birth dates just after the cut-off used for selection in age-grouped sports and it is hypothesised that such relatively older sportspeople may enjoy maturational and physical advantages over their younger peers. There is, however, little empirical evidence of any such advantage. This study investigated whether schoolchildren's physical performance differed according to which quarter of the school year they were born in.Mass, stature, BMI, cardiorespiratory fitness, strength and power were measured in n=8550 10-16 year olds (53% male). We expressed test performance as age-and sex-specific z-scores based on reference data with age rounded-down to the nearest whole year and also as units normalised for body mass. We then compared these values between yearly birth quarters There were no significant main effects for differences in anthropometric measures in either sex. Girls born in the first quarter of the school year were significantly stronger than those born at other times when handgrip was expressed as a z-score. As z-scores, all measures were significantly higher in boys born in either the first or second yearly quarters. Relative to body mass, cardiorespiratory fitness was higher in boys born in the first quarter and power higher in those born in the second quarter.The relative age effect does not appear to significantly affect girls' performance test scores when they are expressed as z-score or relative to body mass. Boys born in the first and second quarters of the year had a significant physical advantage over their relatively younger peers. These findings have practical bearing if coaches use fitness tests for talent identification and team selection. Categorising test performance based on rounded-down values of whole-year age may disadvantage children born later in the selection year. These relatively younger children may be less to gain selection for teams or training programmes.

National Strength and Conditioning Association Position Statement on Long-Term Athletic Development

“…Because of the influence of growth and maturation on measures of physical performance (22,261), relative risk of injury (81,113,258), and the propensity for early maturing youth to be selected in sports teams as a result of the relative age effect (89,93,226), it seems plausible that practitioners should attempt to monitor physical growth throughout childhood and adolescence. Recent reviews have provided summaries of existing methods for the identification, or at least estimation, of biological maturation (145,156).…”

Relative Age Effect of Sport Academy Adolescents, a Physiological Evaluation

“…Given the talent, or the ability to reach the elite level in sports, is evenly distributed among birth quarters and that the RAE has not played a part in the athletes' development and acceptance into the sports academy, we would have expected to see a somewhat uniform distribution of accepted students from different birth quarters, reflecting the monthly birth count of the population in general. We would also expect to find significant differences in characteristics directly linked to sport performance, just as studies have done in non-selective populations according to birth date [32,33]. That was not the case, except for lean mass and the 1000 m run test.…”

Player Selection Bias in National Football League Draftees

“…This potential disparity in growth and maturation may lead to a physiological and cognitive advantage for older athletes within a particular cohort (4,24,29,30,33). These physiological adaptations may lead to better performance and ultimately a player selection bias from coaches and scouts (6,16) leading to greater access to competitive settings, coaching, and training (16).…”