Children who wait until they're older to specialise in high-level sport are less likely to burn out, while the month they're born also should not affect long-term prospects, according to the results of a recent study.
Researchers from the University of Sydney, in collaboration with Swimming Australia, examined the impact age had on overall performance.
They looked into the representation of 6,000 athletes at the National Swimming Championships between 2000 and 2014, examining the birth month of each swimmer and their ongoing participation over the time period.
The study found that in the younger age categories (between 12-14 years), the older swimmers born in the category had greater involvement, while in the older categories (between 17-18 years) younger swimmers in the category were over represented.
The research was conducted in the lead-up to the Tokyo Games and has lead to the review of Swimming Australia's competition guidelines.
Lead author and sports and exercise psychologist Dr Stephen Cobley said the results tested the 'relative age affect', which took into account maturity and early growth. As a result, it generally saw older competitors within age groups given greater access to development programs and selection advantages.
"However our research shows there are a lot more relatively younger athletes making the qualification times and competing at national swimming at the time of transition to adult competition, so if you just wait the influence of early physical difference will slowly disappear," Dr Cobley said.
And in girls the 'relative age effect' dropped off earlier than their male counterparts.
They also examined the impact early specialisation had on representation in each age bracket.
"We also found athletes who started competing in the earlier years tended to drop off and not return annually, compared to those who didn't compete until the older age brackets," he said.
"This could be due to a number of things including intensive training loads, burn out and loss of interest related to earlier specialisation.
"From a sports development perspective our research suggests you are more likely to pick genuinely promising athletes if you delay talent identification, athlete selection and specialisation until 15,16 or even later to account for the later development trajectories of some athletes."
Swimming Australia's High Performance Pathway Manager Jamie Salter said the research supports the organisation's athlete development program and as a result it's made some changes to better support pathways into elite competition in the lead-up to the Tokyo 2020 Olympics.
"For many young swimmers, their age and the difference in physical size can have a big impact on swimming times which often results in some swimmers gaining an advantage and the same time, discouraging others purely based on the month of the year that they were born," Mr Salter said.
"As such we have changed the minimum age for swimmers to compete, and this will be different for boys and girls due to girls maturing earlier.
"We are also implementing events and strategies to help maintain involvement in later post-maturation years."