Who plays? Lessons from the Little League World Series & USA National Team
When were you born and what is your biological age?
Youth sport is a major vehicle for physical activity but for some parents and coaches they see it as a gateway to “elite” performance pathways. During the elementary school years, participation rates in youth sports are relatively high; however, as youngsters enter the middle-school years (ages 12-13) about 70% of them will have dropped out of sport! 70%!! Of course, there are many reasons including ability, friends, other interests, etc. – and we will leave that for another post.
Amongst boys, in particular, there are two other factors that come into play.
The Relative Age Effect: When were you born?
Obviously, skill level plays a key role. But perhaps even moreso, how about when the kid was born? Yes, seriously. What month was the boy born? January? April? October? And how does it relate to the cutoff date for the age group?
This is referred to as the Relative Age Effect, or what some have called the Birthdate Effect. Are you the oldest or the youngest in your age group? Think about it. There could be a 364 day difference between two boys in the 12-year old age bracket. That’s 364 more days of growing, maturing, and developing for the older boy who is advantaged by the relative age effect or their birthdate.
Don’t believe me? Several research papers have highlighted the RAE across a range of select or elite youth sports (“elite”; I hate that word in youth sports – just sayin’).
Here’s Exhibit A: 53% of players selected to the U12 USA Baseball National team from 2013-2017 were born in January – March and another 29% were born in the second quarter of the year. Only 8% were born in the last three months of year. Relative age matters!
Relative Age is not the same as being an early maturer
Please, please note that the relative age is not the same as being an early maturer. That’s worth stating again - relative age is NOT the same as being an early maturer.
Relative age is based on when you are born in relation to the cutpoint for participating in an age group. A child can be born within the first quarter of the selection period and can be an early, average or late maturer, and this also holds for being born in the last quarter as well. However, the biggest potential advantage is when one benefits from both relative age and biological age (i.e. first quarter relative age and early maturer for size and power-based sports; unless genetically small).
Maturity also matters in some sports
Biological or physical maturity status also matters in some sports. An early study of the 1957 Little League World Series showed that 71% had a maturation age more than chronological age. My personal correspondence with many in European youth soccer academies suggest that there are very few late maturers.
Size matters in many sports that middle school boys enjoy as well. And you guessed it, many youth who are selected for “advanced” teams are taller and bigger – and hence stronger. This could relate to either genetics or maturation or both.
Exhibit B: Maturity effects on body size and functional capacity in junior soccer players (Malina et al. European Journal of Applied Physiology 2004)