SSPC Southern Suburbs Physio | The Relative Age Effect in Sport
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The Relative Age Effect in Sport

There has long been discussion, debate and medical investigations to try and determine if elite athletes are born, or made! Some may have heard of the quite famous 10,000 hours rule which stated that 10,000 hours of deliberate practice was needed to become elite in any field. This came from the book Outliers, written by Malcolm Gladwell, in which he helped validate his argument by stating that early access to getting 10,000 hours of practice allowed the Beatles to become the greatest band in the world. This rule was also dissected more recently in the great book “The Sports Gene” by David Epstein which compared the training effect to genetical predisposition to sporting greatness.

Studies seem to indicate that the 10,000 hour rule alone is not enough to ensure a person achieves elite status in their field, and we all know there are plenty of exceptions to the 10,000 hour rule: whilst there is a general consensus that deliberate practice is important, it seems it may not be quite as important as previously argued.

Another theory mentioned to me by a friend recently, and one that I knew little about, was the Relative Age Effect (RAE), which proposes that unique talent we see, especially in junior sport, may be a consequence of circumstance (birth date) more so than talent. In other words, being born in a particular month could greatly influence an athlete’s prospects for long-term success; in the book mentioned above, Gladwell uses Canadian hockey as an example where the cutoff date for age-class hockey is January 1, and his detailed studies showed up to 40% of team members were born in the first quarter (January to March) of the year.

Another fascinating statistic coming from the 7th International Children’s Winter Games in 2016 showed older children appeared to have a 3.5 times greater chance of being selected than younger athletes. Yet more research shows that in European soccer, players born later in the selection year are more likely to drop out of the sport or be released from professional soccer clubs. A clear relative age effect was also found for all the European soccer national youth selections in the U/15, U/16, U/17 and U/18 age categories in a 2004 study. Hockey, tennis and basketball have also been shown to have significant relative age effects across a range of age groups.

In effect, a person born in February has an extra 10 months of growth over someone born in December, making that February person more likely to experience earlier maturation, which is closely associated with improved speed, strength, and muscular endurance in comparison to their younger counterparts.

While perhaps not as insignificant to an adult, to a 12-year old footballer or basketballer it can mean completely different body types, co-ordination and skill levels. Is it possible therefore that the relatively older, bigger, stronger, and more coordinated kids are seen as gifted or talented, and as a consequence get selected in more representative teams and get exposed to a higher level of coaching at a younger age?  No doubt in today’s push for elite sporting performance, talented athletes are identified from a younger age and enter programmes to help them develop into elite athletes. These older athletes may be more likely to persevere in sport, by being able to actively dominate in physical bouts and key performance measures, as well as getting greater exposure to these better opportunities. It sounds plausible on the other hand that the relatively younger, slower to develop players, don’t get these same opportunities, might get overlooked, become frustrated, and perhaps get lost to a sport before they’ve had time to flourish.

As with many things in health, there’s always “the other side of the story”! Further research has indicated whilst the RAE can be a factor in junior levels of sport, this effect literally disappears in adult levels of sport. In fact there is some research that shows that younger athletes (born later in the calendar year) may have longer and more successful careers than their older counterparts! The reasoning behind this is that if we can keep these younger athletes in the sport for long enough (and not have them become disillusioned with their older stronger buddies) they may have the necessity to develop specific technical or tactical skills needed to be able to compete successfully against their older, more mature opponents. In the long run, this may result in a larger skill set, making them better performers – sort of like a “Big Brother” effect where a younger child credits an older sibling for being so dominant in the childhood years, and forcing the younger child to compete against a bigger, more advanced opponent. In this type of case, once the younger child matures and lack of size is removed from the equation, overall skill becomes the determining factor for the difference in success.

When looking for young talent to place into representative teams, advanced training systems or academies, the potential bias of RAE should be considered. Several recommendations have been proposed to try and help resolve the relative age effect, and these include:

  1. Original suggestions promoted a change in the age-group cut-off date (e.g. from January to June), effectively rotating cut-off dates from year to year. However, changing the cut-off dates only leads to a transfer of a relative age effect, rather than elimination of the effect.
  2. Another solution has been to try to group athletes according to physical classification (i.e. height and weight), similar to that routinely adopted in boxing and wrestling. Not only would this be an enormous logistical problem, but there’s not a lot of evidence behind the validity of this for a lot of sports.
  3. Perhaps a more realistic option is to delay talent identification and elite/representative sports environments until our kids are a little older, even post puberty, to allow growth and development to have potentially less variance for kids of the same birth year.

Point 3 above may even help with the relatively high number of growth/sport related injuries in adolescents we seem to see these days. It is quite amazing when assessing younger children to hear the vast amount of activity they do. Now we know that the opposite (too little activity) is probably more common and has just as serious, if not more serious, health effects, but there are many younger children that simply seem to be doing too much, and possibly more importantly, too much at an intense/advanced/elite level of training. This is backed up by a 2016 study that found a significant RAE on sports injury in prepubescent children (defined as 5 – 13 years of age).

Going hand in hand with the topic of exercise volume and intensity is another complex topic – are children specialising in a sport too early? Once again, in the clinic when assessing younger children, it is often amazing how much of a single sport these kids do: club, school, representative, state – all in the one sport, and all on a growing, immature skeletal system. This is a topic for a separate blog, but there is quite an amount of research to suggest that young children should be exposed to a variety of sports, and not specialise in one sport too early in life. This exposure to different sports will not only benefit their physical health and reduce their injury risk, but also enhance their motor skill development across a variety of activities, which can actually benefit them in their chosen sport later in life.

So in summary, the common practice of placing children into age groups for sport may provide early benefit to those who are more developed physically, emotionally, and cognitively, perhaps simply as a consequence of birth date. Offsetting that is the thought that those who are born in the later stages of the year could actually experience an unintentional bias in their long-term sporting success.

Certainly at the very least, as parents and coaches, we should all be very aware that during pre-pubescent and adolescent years, physical attributes such as height and weight should be considered in the planning of training and if possible competitive situations, and that equal attention should be given to those that may not seem as “expert” as their peers within the sport. Exposure to different sports and skills, not just exposing children to elite teams and levels within the one sport, may have a lot of benefit to their future performance. And for those searching for young talent, you need to ensure that biological maturity is not mistaken for performance superiority!

Anthony Lance

SSPC Physiotherapist

 

References available on request

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