Bio-banding groups athletes based on growth and maturity, not just sex and age

Can it help reduce the relative age effect in sport? Yes, and it can also reduce selection bias between early- and late-maturing athletes. But it's not for all sports.

Photo by John Torcasio on Unsplash

Bio-banding, if used effectively can reduce some consequences of the relative age effect. It can also help diminish selection bias, which often relegates late-maturing athletes. However, in a 2017 article (see below) I questioned its practical implementation because the maturity assessment of athletes requires several physical measurements and the understanding of what to do with the data once it’s collected. Most youth sport organizations have neither the expertise nor the logistical resources to sustain a full bio-banding scheme.

“Bio-banding is the process of grouping athletes on the basis of attributes associated with growth and maturation rather than chronological age.”

Grouping by height and/or weight is common in combat sports and has also had limited use in collision sports, but most use sex and age to categorize youngsters. This works well enough but does not account for differences in weight, height, or skill levels, which can be significant especially when early maturing youngsters are in the same training group or competitive classification as same-age, late maturers. Bio-banding mitigates maturational differences so that athletes receive appropriate physical challenges regardless of their maturational status.

Using sex and age categories alone sometimes produces significant relative age effects, and perpetuates long-term consequences for both early- and late-maturing youngsters.

How it can be used

Bio-banding considers the athlete’s current maturational status, the athlete’s age at peak height velocity (APHV), and the athlete’s rate of growth. APHV is determined by calculating the athlete’s maturity offset, which I have written about previously. The rate of growth is determined from the percentage of predicted adult height (PAH). 

In 2016, the English Premier League, an organization with plenty of logistical support and expertise at its disposal, tested a bio-banded soccer tournament with athletes grouped by maturity rather than age. Clubs played athletes between 11 and 14 years old and whose percentage of PAH was between 85% and 90%. Clubs were also asked to consider each players psychological and technical development during selection.

Since peak height velocity (PHV) occurs between 88% and 96% of PAH, the 85 to 90% PAH grouping in the tournament represented athletes who were in the early-adolescence period of growth, or early puberty.

You can read about the league’s and players experience with this kind of grouping here, but results of the grouping method were positive.

“…players described their experiences as positive and agreed that the bio-banded games presented them with unique challenges and a more diverse learning experience.” Source: Bio-banding in sport: Applications to competition, talent identification, and strength and conditioning of youth athletes.

Bio-banding may not make sense for all sports but for organizations that have the resources to use it it’s a good way to reduce both the relative age effect and the selection bias baked into the system when sex and age are the only grouping variables used. 

---

This article was originally published in December 2017

What is bio-banding?

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 allowing 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. 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; it’s an interesting idea but I’m not convinced it’s realistic. 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 most clubs already assign swimmers to training groups based on a combination of age and ability.

There are practical social 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 new and maybe better.