Can Your Birth Date Make You a Better Athlete?

Will Your Date Of Birth Affect Your Sporting Success?

Take a  look at the following chart:

Copy of Team Member Month of Birth - Percentages from January

The chart outlines the birth month of kids selected in a particular representative Under 13 athletics team during a six-year period. The horizontal axis shows the months; the vertical axis shows the percentage of team members born in that month.

What do you notice?

You probably noticed that an extraordinary number of athletes – about twenty percent, or one in five team members – were born in October. Wow. Why October?

Let me put the figures into context.

The sport in question is an Australian summer sport, conducted in a season that takes place roughly between October and March. The age group eligibility cut-off date is 30 September. Therefore if you are born in October, you will be one of the oldest athletes in your age grouping. Let’s look at the chart again, with October listed first on the horizontal axis.

Team Member Month of Birth - Percentages

Does it now make more sense? What can you now see?

By further analyzing the figures, two other interesting observations emerge:

  1. Forty-three percent of team members were born between October and January.
  2. Seventy-four percent of athletes were born between October and April (i.e. in the first six months after the age group eligibility cut-off date).

These figures suggest that it could be an advantage to be born earlier in this sport’s age group eligibility period.

A surprising amount of research and reading is available on this phenomenon, commonly referred to as the “relative age effect”.

What is the relative age effect?

“The relative age effect refers to the overall difference in age between individuals within each age group, which may result in significant differences in performance.”

The relative age effect has been found to exist in many youth sport settings.

Malcolm Gladwell, in his book “Outliers – The Story of Success” examines the issue, citing Canadian youth ice hockey, where we learn the eligibility cut-off date is 1 January.

He says:

“A boy who turns 10 on January 2, then, could be playing alongside someone who doesn’t turn 10 until the end of the year – and at that age, in preadolescence, a twelve-month gap in age represents an enormous gap in physical maturity.”

It makes sense. The earlier-born athletes, benefiting from the critical extra months of growth and development. will have an obvious advantage in sports that require speed, strength and coordination.

Further to this, the younger the athletes, the greater the potential advantage. This is demonstrated in the following statement that can be found on Wikipedia:

“The difference in maturity – which can be extreme at young ages: a six-year old born in January is almost 17% older than a six-year old born in December in the same year – causes a performance gap that persists over time.”


A performance gap that exists over time? 

But wait – doesn’t the relative age effect flatten out over time? Won’t kids grow out of it?

Maybe not.

What happens when young kids – benefited by extra maturity over their later-born age group peers – are defined as “talented”? Malcolm Gladwell says they will most likely get better coaching, their teammates will be better, they will play more, and they will practice more.

He writes:

“In the beginning, his advantage isn’t so much that he is inherently better, but only that he is a little older. But by the age of thirteen or fourteen, with the benefit of better coaching and all that extra practice under his belt he really is better . . . “

This relative age effect is seen widely across junior sports. Contrary to popular belief, it is something that may not “even out” as the athletes reach and pass through adolescence. With the early talent identification systems and representative teams common in many sports, it may have further reaching effects than many people realise.

Coaches, sports parents and sporting organisations need to be aware of this phenomenon and avoid making decisions about who is good or talented at an early age. Otherwise, as Malcolm Gladwell surmises, we will “. . . end up giving a huge advantage to that small group of people born closest to the cut-off date.” He says we may also  “. . . prematurely write off people as failures”.

Will your date of birth influence your sporting success? The evidence seems to say that yes – it possibly can. The next question to ask is are we content with this situation and if not, what can youth sports do to address it?

What are your thoughts about the relative age effect?

Does the relative age effect really exist? What is your experience of it? What should be done to address it? Let me know by using the below contact details.

Further reading

Outliers – The Story of Success by Malcolm Gladwell from Amazon

Outliers – The Story of Success by Malcolm Gladwell from Booktopia

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Darren Wensor is a sports development professional, coach educator, specialist coach of young athletes and founder of the blog Learn more about him here and connect with him on TwitterFacebookLinkedin, Instagram or via email.

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