Do you know in which month Tiger Woods was born?
Do you know in which month Roger Federer was born?
Do you know in which month Lionel Messi was born?
There is something in sport called the Relative Age Effect (RAE). The relative age effect is a biased spread of elite athletes’ birthdates with an over-representation of those born at the beginning of any given competitive year (e.g., September in most Western societies) and an underrepresentation of those born at the end of any competitive year (e.g., August). (Rees et al., 2016). What the relative age effect means is we find more elite athletes in a particular sport with birthdays in September compared with August when the starting age (e.g., u-11 age group) begins in September, for example.
The concept of RAE was first introduced by Roger Barnsley and his colleagues in the early 1980s while studying Canadian ice hockey players. They noticed a significant overrepresentation of players born in the first few months of the selection year. This trend was attributed to the age cutoff dates used in youth sports, where players born in the same calendar year were grouped together. As a result, children born earlier in the year had several months of additional physical and psychological maturity compared to their younger counterparts.
One key factor contributing to the RAE is the developmental differences among children of the same age. In the early years of youth sports, small age variations can translate into notable differences in physical, cognitive, and emotional development. Children born in the first months of the selection year may be more physically mature, possess better coordination, and have a psychological edge over their younger peers. Coaches and talent scouts, relying on immediate observable advantages, may inadvertently favor older athletes during talent identification processes.
One study that gathered all the research studies from 1984 to 2007 examined non-elite, junior-elite and elite-level athletes in several sports: baseball, basketball, ice hockey, soccer, and volleyball showed strong support for the relative age effect. But is the evidence convincing? There may be inconsistencies, too. For instance, in some elite sample (those at the mature end of the sport), the relative age effect was clear in ice hockey and baseball but not in basketball, golf, handball, soccer, taekwondo, volleyball, American football and various other unspecified Olympic sports.
It seems, therefore, that there is hope for every aspiring athlete and the devil is in the detail. For instance, there is evidence at the junior elite level in ice hockey that the relative age effect is more prominent in boys than in girls. But there is more detail to explain for sports. With younger athletes, there are several other factors we need to consider such as when the athlete chooses one sport over another and drop out. One study examined the relative age effect accounting for all players who registered to play soccer as the comparison group, and the relative age effect disappeared.
Even as we move up through levels from junior to senior sport, at the elite and super-elite level, the advantage of been relative older is moderate to low.
Whatever advantage conferred from being born in the first two quarters of the year may disappear when the athletes reach an elite level. Of course, this begs the question, what would you do if you were selecting talent? Would you pay attention to one’s birthdate?
Several factors contribute to the perpetuation of the RAE. Coaches and scouts, seeking immediate success, may unconsciously prioritize older athletes, overlooking the long-term potential of younger talents. The psychological impact of being among the older and more developed players in a cohort can also boost confidence and motivation, further enhancing performance and reinforcing the advantage.
To address the challenges posed by the RAE, some sports organizations have implemented changes to their age-grouping systems. For instance, adjusting the age cutoff date or adopting a biannual age grouping system can help mitigate the developmental differences within a single cohort. By grouping players based on a smaller age range, the relative age advantages become less pronounced, allowing for a more equitable assessment of talent.
If we used the literature as a guide, then the relative age effect is unhelpful for talent selection or talent development. Coming from the opposite direction, it’s not the child’s or athlete’s fault when they were born; what matters is how the structures of sport can adjust for these relative age effects. If the child is taller because she is 9 months older than another, we as coach and policy maker need to make the adjustments, not the child. Another key point is that age is but one factor in the talent development process. We cannot forget genetics, body size, shape and its components, psychological skills, motivation, personality traits, environment, support from parents, coaches, peers and pals, volume of sport-specific practice, training and specialisation.
Do you know in which month Tiger Woods was born? December
Do you know in which month Roger Federer was born? August
Do you know in which month Lionel Messi was born? June
For more detail, please read the excellent article by Tim Rees and colleagues
Rees, T. (2016). The Great British Medalists Project: A review of current knowledge on the development of the world’s best sporting talent. Sports Medicine (Auckland), 46(8), 1041–1058. https://doi.org/10.1007/s40279-016-0476-2
Image by tigerlily713 from Pixabay
