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What is bio-banding? Can it help reduce the relative age effect in sport?
Anyone who has coached young athletes for any length of time knows about the relative age effect (RAE). Even if you've never heard the term before you've seen early maturing youngsters outperform their later maturing comrades even though both groups are technically the same age. Over time this leads to an accrued selection bias that is all but hardwired into sport development systems worldwide. This bias sees relatively older athletes receiving the benefits of selection, coaching, and competitive opportunities not available to their relatively younger counterparts primarily due to a perception of higher abilities. A USSA Malaysia analysis illustrates this effect with fitness testing data.
The RAE occurs as a result of the relationship between chronological age and administrative cut-off dates for age determination. Early attempts at mitigating the RAE centered on adjusting age cut-offs to something that allowed for more accurate age calculation and smaller age cohorts in competition. For individual sports this is an easy fix: Simply calculate ages of competitors based on the first day of a competition and reduce competitive divisions to single year groupings. But for team sports, and for general training in all sports, calculating ages on 'the day of…' is not really practical.
But even the 'day of...' method of calculating age is not always the best way of grouping children for competition; additionally it has no real use in grouping for training.
Grouping young athletes by their biological rather than chronological age
Bio-banding is a more sophisticated attempt to mediate the relative age effect in youth sport. It takes a more sport specific approach to grouping athletes than simply relying on age cohorts, though age is still a factor. Size, weight, skill, experience, and other factors peculiar to certain sports are all considered when bio-banding athletes but determining a maturity category for each athlete is the key to the bio-banding method. (You can download a tool that helps calculate this from the Science for Sport website. The tool is a spreadsheet that uses a few simple measurements like height, weight, and parent height to calculate a maturity category.)
The categories are pre-, early-, mid-, and late-pubertal and knowing which category a youngster is in helps assign them to training groups and competitive divisions. But while the categories may offer more accurate or specific groupings than age they are only guides. Real bio-banding has to consider experience (training age) and sport specific skills, as well as psychological attributes for strategy, tactics, and leadership.
Another way to describe bio-banding is grouping young athletes by their biological rather than chronological age. This takes a certain amount of know-how on the part of coaches and club administrators.
Is bio-banding practical?
As a coach I read the details about bio-banding and think that this is the way it could or should be done but then I have to get back to reality. The kind of science and support required to administer a real bio-banding system rarely exists at the youth sport level. Youth sport clubs and teams will have to come up with their own bio-banding methods which may vary depending on the number of athletes they are dealing with and with the knowledge and experience of their coaching staffs. Larger numbers of athletes make it more practical to assign training groups by maturity category but knowing each athlete's maturity level can aid experienced coaches even with small training groups.
As a former swimming coach I know that most clubs already assign swimmers to training groups based on a combination of age and ability.
There are practical concerns though. Older athletes just joining a competitive swimming program won't have the same level of skill as others their age who have already been involved in the sport for a number of years and already possess well developed skills. Assigning a new athlete to a group with a much higher level of skill development is not really a good idea if we are concerned with him having a good sport experience. On the other hand assigning him to a group equal to his beginning level of ability would mean training with much younger athletes. Following the science in this example would create an uncomfortable social situation, one the new athlete is unlikely to enjoy.
Depending on the technical expertise of club administrators some form of bio-banding may help keep late maturing athletes involved in sports longer and encourage early maturers to focus more on their skills and technique rather than rely on their physical advantage. Both of these outcomes would be good for youth sport overall; not only would more youngsters stay in sport longer but their level of performance would be higher as a result.
It's not yet clear if bio-banding is a practical solution to the relative age effect. It certainly looks good on paper but real-life implementation will tell the tale. It's also not clear exactly how bio-banding ideas will be implemented in various sports and it will be interesting to see if some sports have the will to reject the 'easy' age categories and try something that is new and maybe better.
Bill Price (email@example.com) is the owner and Chief Data Scientist at Sportkid Metrics.