It could have been very different for Gareth Bale. During his time at Southampton’s academy, the Welshman — who would go on to achieve incredible success, winning five Champions League titles with Real Madrid — was almost released.
It was nothing to do with talent, but more his stage of development relative to his age.
“If you are an early developer and have already gone through your growth spurt, you’re probably performing quite well,” says Dr Sean Cumming, a senior lecturer at Bath University and internationally recognised as a leading expert on growth and maturation in sports.
“But if you’re in the middle of your growth spurt at the point of being assessed, there’s a good chance you’ll get released. Gareth Bale was close to it at Southampton. He survived a coaches’ vote by three to two because medical staff flagged he was in the middle of his growth spurt.”
As sport evolves and, in some cases, reforms, the concept of bio-banding grows in significance. Across different sports, inherent biases are being removed, improving the richness of development and ensuring precocious talents are not overlooked. In Bale’s case, he was lucky. There are countless instances of footballers, cricketers, gymnasts and even horses being hamstrung by physical biases.
Traditionally in team sports, young athletes are organised by year group. However, during the maturation phase — the progress towards adulthood — a child’s biological maturity can vary dramatically. In extreme examples, the difference can be as much as six years.
And the inherent trends — or biases — have always tended to favour early maturers, leaving the smaller athletes behind.
“What we’re seeing across the football academies is from the ages of 11, the bias increases towards the early developer,” says Cumming. “By the time you get to 16 or 17 years of age, 60 to 80 per cent of an age group are early developing boys.”
Clubs across Europe are progressively more aware of selection bias towards older, more physically developed players. This is illustrated in the recruitment of players. A study conducted with Dutch side PSV showed subconscious scouting biases towards more developed players. To mitigate this, trial days had players in age-ordered shirt numbers to keep watching scouts aware.
Other measures to overcome prejudices include specific trial days — several teams in the UK have hosted trials for players born in the last quarter of the competitive year, which is when the youngest of an age group are born and typically at an immediate disadvantage. One study from the U.S. backs this theory; research suggested late-maturing players born in the fourth quarter of an age group were 20 times more likely to be released.
“It is not because they’re great football players, but because they are simply bigger, stronger and faster,” says Cumming. “In places like Manchester United, there are only two per cent of late developers. In many of the academies we’ve worked at, we would not find any late developers from the age of 14 onwards. They had already been squeezed out of the system. Those maturing on time also got squeezed out.”
Cumming was approached in 2015 by the Premier League (Laurie Lapworth/University of Bath)
To combat bias towards early maturers, United, led by Sir Alex Ferguson, started to implement a practice that grouped children by their biological status — a process now known as bio-banding. This is when athletes are grouped on their timeline of maturation as opposed to their chronological age. United were considered best practice, with players including Jesse Lingard and Danny Welbeck, both late maturers, benefitting from more informed biological decision-making.
“United knew they had these biases,” says Cumming. “When Sir Alex was there, United set up a maturity screening programme to figure out why certain kids were getting injured through their growth spurt. They created a system for measuring physical development, so they could tell when kids were going through growth spurts because boys in the middle of one temporarily lose developmental attributes such as balance, coordination and technical traits. They are also more susceptible to getting injured. For example, when we did bio-banding at Bournemouth, by identifying which players were going through growth spurts, we reduced injuries by 70 per cent and reduced the injury burden by 90 per cent.”
Early maturers can become quite awkward and gangly, affecting their ability to control and manipulate the body as well as their general mobility. This, naturally, contributes to a downturn in performance.
Bio-banding is not a formative concept that began at United, however. In Auckland, New Zealand, junior rugby teams would be forged based on their weight and age, indicating a rough understanding of biological maturity. Indeed, while it was not coined as ‘bio-banding’ then, the idea was first endorsed early in the 20th century, when children were evaluated in their ability to do child labour.
Athletes are grouped by their biological maturity by using a percentage of their predicted adult stature. To ascertain an athlete’s biological age and therefore band, Cumming devised systems that were put into practice by the Premier League and form part of their EPPP (Premier League Elite Player Performance Plan) syllabus.
“We collect the heights and weights of the athletes,” Cumming explains. “We get their parents’ heights and dates of birth, so we can predict the kid’s adult height and express their current height as a percentage of their adult height. You may have two boys exactly the same height, but one might be predicted to be much taller and the other relatively short.”
But measuring a child’s height and weight only grazes the surface of bio-banding.
From arranging football teams, the first bio-banded cricket matches, overcoming ethical challenges in gymnastics and introducing the practice into horse racing, The Athletic has spent the past six months observing how bio-banding is applied across four different sports and whether it could fundamentally change talent identification…
Football — Southampton Football Club
Football had been a late entry into bio-banding, but the sport is pushing the envelope more than any other when it comes to research into physical growth.
Southampton are regarded as one of the forerunners in implementing best practice, having hosted the world’s first bio-banding tournament in August 2015 at Staplewood.
“It all started for me at the club,” says James Bunce, current director of performance at Monaco. Bunce started at Southampton before heading up the Premier League’s performance programme and then moving across the Atlantic to become U.S. Soccer’s director of high performance. “I was lucky enough to be (at Southampton) during a really golden generation.
“Alex Oxlade-Chamberlain was there. He was in the under-14s. He is what you call the epitome of a late developer. Back in those days, he was just small. Alex was really talented in drills — you could see his touch, his movement, his skill and finishing — but when he played in games, he would look so much poorer and wouldn’t look like he could cope.
“Rationally, it didn’t add up. How could this skilful and confident kid not be able to perform in games? So we had to decide what to do with him. Luckily, we had a really good academy director in Matt Crocker (now sporting director of U.S. Soccer) and with conversations with him, Alex and his parents — his mum was a physio and his dad, Mark, was an ex-player — we made the decision to keep Alex at the club but hold him back a year and stay in the under-14s. He then broke into the first team when he was 16. It was crazy, but it was a lightbulb moment in my head as a fledgling performance guy in the industry.”
Southampton had a head start on fellow Premier League sides at the time, with their sports science staff comprising several Bath University alumni and former students of Cumming. Research into bio-banding was led by Bath PhD student Megan Hill in collaboration with Southampton. She assisted academy staff in better accounting for developmental differences in young players.
(Laurie Lapworth/University of Bath)
“I joined Southampton three and a half years ago and they were already doing bio-banding,” says Joe Brookman, an academy strength and conditioning coach. “I came from Everton and it wasn’t a concept we were doing up there.
“We’ve tried to implement a different version of what we’ve done in the past. We’ve always done bio-banding games, but they’ve been quite singular at times. However, in the last two years, we’ve done it in what we call a ‘bio-block’ for a month in January.”
Players are banded into groups based on their levels of maturation and predicted adult height. Implementing bio-banding over a four-week block, as opposed to one-off games, enabled Southampton to learn trends and understand the more nuanced pros and cons within the mental and psychological development of players. Bio-banded groups remained the same across all aspects of the training programme, including gym sessions and martial arts work, put on by Southampton to encourage different physical skills including judo and taekwondo.
“We found that doing a bio-block gave all players time to find their way of playing and gel into the system,” adds Brookman. “We’ve seen good returns from the last couple of years. It allowed coaches to have a better idea of their perception of players in terms of their longevity at the academy.”
(Laurie Lapworth/University of Bath)
Bio-banding tests the technical and social development of an athlete. In 2019, sports scientists from the U.S. youth national team performed an experiment across 33 under-13 and under-14 players, focusing on their ability to assimilate technical and tactical information. It found that bio-banded groups helped to “significantly” increase the number of duels in games and decrease the amount of time spent on the ball. This improved the overall standards of competition and found players were all of relative similarity in their physicality.
“Athleticism is a key attribute in American sports, so again plays into the hands of stronger and early maturing athletes,” says Bunce. “In America, I was able to do things on a big scale. When we spoke to the early or maturers during tournaments, they all emphatically appreciated it. They really liked this ability to challenge themselves in a different environment.”
There was a notable trend towards a more even spread of possession, reducing running distances but not affecting the total number of passes completed, giving players a more technically and tactically challenging proposition.
A parent watching their child play with those younger than them can cause tension, particularly if they are yet to understand the functionality of the practice. Some read into it as a slight of coaches not rating their child’s ability. Southampton have understood the importance of explaining the concept of bio-banding, reaffirming it is not based on technical aptitude but on what may be most conducive to a player’s development.
U.S. football has introduced workshops to parents wanting to remove the taboo of a player “playing down” as a bad thing.
“Everyone talks about little Tommy who needs a help,” says Bunce. “But the biggest danger for the sport is the big kid who is dominating. What we found with data is that you have an industry totally saturated with early maturers but not a high proportion become elite professional players. Therefore, the highest population percentage you are recruiting in the U.S. is the least amount actually coming into the sport. So we put a lot of emphasis on those bigger kids going up against bigger kids and finding it hard.”
At the start of every bio-banding block, Southampton send educational videos to parents and will receive feedback from players, parents and coaches once the block is over.
One key takeaway was that 20 per cent of parents said they did not see any palpable benefit in their child taking part. It is accepted that bio-banding will not necessarily stimulate or enhance every athlete. Some later-maturing boys, for instance, may already be excelling in their age group and do not need to play with biologically younger peers.
“Every player will have a different experience,” says Brookman. “It might be an older player who’s late developing goes into a younger age group. Suddenly you see their leadership skills. They might be demanding the ball more whereas they are shy in their age group. Purely from a physical perspective, bio-banding levels the playing field. You can see players able to utilise other aspects of their game.
“On the flip side, it paints a good picture of our early maturing boys. If they’re just cruising because they’re physically dominant, we’re probably not challenging them enough. Bio-banding is a tool to assess players’ potential and recognise selection shouldn’t just be early maturing players, because there are late maturers who are just as good, but you need to wait for them.”
Cricket — Gloucestershire Cricket Club
Marlborough College, Wiltshire. It is 8.40am in late May and the cricket season is well underway.
Gloucestershire Cricket, in collaboration with its partner county, Wiltshire, are about to host the first bio-banded cricket event in Britain. With analysts and coaches from both clubs, physical screening takes place for the next couple of hours, measuring the heights and weights of players from the ages of 12 to 14.
Jump test equipment and light gates that measure speed are set up. Parents’ heights have already been collected by Tom Brazier, the talent pathway strength and conditioning coach at Gloucestershire, who starts by explaining the process and how the day will work. He delivers an introduction, emphasising bio-banding is not about “physical skills, but physical assessment”.
“We’re thinking outside the box,” says Brazier. “As more resource comes into cricket, this will be the norm. But until then, one county has to set the standard. Hopefully, that’s going to be us.”
Physical testing has been completed and three games are scheduled to take place concurrently. Brazier gathers players into one line on each pitch. Twenty-four under-14 players are lined up in height order, with a picture taken. The smallest and tallest players stand next to one another, capturing the height discrepancy.
Each age group lined up in height order (Jacob Tanswell/The Athletic)
Players will stay in their age group for the first game — 20 overs a side or, for non-cricket watchers, 120 deliveries — before splitting up into bio-banded groups at 2.30pm, which Brazier organises. “You do know you relegated one of our players who scored a ton last week?” smiles one Gloucestershire coach.
“If you’re in the top third of maturation from Wiltshire, you’ll play against the top third of the Gloucestershire lads,” Brazier adds. “We’re not going in with too many expectations. There are only four lads across all three pitches that are late maturers. We had one lad that was around 30 kilograms and another that was 86 kilos in the under-13s — that highlights the difference.”
There is a camera behind the bowler’s arm and on top of the sight screen (which aids the visibility of the ball for the batter) on each pitch. This will be used for evidence when collecting the data, which will take a month to break down fully.
“We’re going to have everything filmed and coded so we can look through themes afterwards,” says Brazier. “I’d anticipate the more mature batters will have a higher strike rate, have a higher boundary per ball percentage and hit more boundaries. The early maturer batters who move up will struggle because they’re so used to dominating slower bowling.
Each pitch had a camera attached to the top of the sight screen (Jacob Tanswell/ The Athletic)
“If you see a player above his biological age (an early maturer) playing well and can hold his own with his technical skills, we could have a beast that we want to invest in. But if that player struggles, you might argue they only score runs or take wickets in their current age group because they’re big.”
As the afternoon goes on, early hypotheses are formed. On the early maturer, typically under-12s pitch, a lot of the runs are scored through backward square (behind the batter’s back shoulder), requiring less power but greater precision. From a bowler’s perspective, there were more catches close to the bat, as the smaller batters struggled to clear the fielders close to them.
One player — an under-13 playing in the early maturer band group — times a crisp shot past the bowler’s right ankle. “You see, he’s just hit straight down the ground,” points out Brazier, who explains that type of shot demands more power. “He wouldn’t be able to do it in the older age group as he wouldn’t have the power, so he’s developing different attributes.”
The boys were split into bio-banded groups in the afternoon (Jacob Tanswell/The Athletic)
“Our cricket selection, not consciously, is generally late developers,” says Thorburn, formerly a professional cricketer at Durham. “What we are seeing today is cricket through a different lens. Ollie Pope was talented at 15 but his technique wasn’t mirrored by the runs he scored. He was small and didn’t have the power to pierce the field. Now he’s England vice-captain.”
There are 72 players at the event, with parents welcome to watch. One mother seeks out Brazier and queries her child (not pictured) being pushed down two groups and onto the youngest pitch. She says her son, smaller than boys his age, was sensitive to being weighed and lined up in height order. Brazier welcomes the feedback and explains that bio-banding’s purpose is to give biologically late developers time to come through the system.
All in all, the day runs smoothly, with positive cricket played. Brazier intends to hold a debrief with coaches, parents and players before analysing the outcomes.
“The coaches’ debrief afterwards will be the most interesting,” he says. “It will show whether there is a sweet spot to identify talent. Do we go with someone not as mature but taking more wickets — is it because they are more skilful? Do we need to give those guys more time and more of an opportunity? Bio-banding in cricket hasn’t been done before… it is exciting.”
Gymnastics — British Gymnastics
“Gymnastics is going through a massive reform and having to bring 21st-century sports science into a culture that’s been closed,” says Dr Tejal Sarika Patel, a pathway scientist at British Gymnastics. “It’s about gaining trust and delving into what the right thing to do is. It’s about changing hearts and minds.”
Generally, talent identification within gymnastics has always been geared towards late maturers, in contrast to other sports.
It is a sport differentiated by aesthetics and suppleness, meaning late maturers, yet to experience pubertal gains such as weight and increased body fat, have been favoured. Late maturers also tend to retain flexibility, agility and speed; all factors in analysing athletic performance.
The school of thought that a female gymnast hits their peak at age 16 has had to change, with Patel tasked with leading reforms. Patel recently completed a PhD looking at growth, maturation and training load in British gymnastics.
“As you go through puberty, your body changes,” says Patel. “If you go through adolescent awkwardness, you will lose skills. Girls will lose their body composition and power drops.
“Boys will get stronger because they’ll develop more muscle mass. But for girls, a lot of technical stuff comes pre-puberty. We are hopefully getting to a point as sport moves on that it won’t matter and we’ll be aware of when a gymnast is going through puberty and therefore know they’re going to go a little bit backwards.”
The purpose of bio-banding within gymnastics essentially hopes to provide a different function to both cricket and football. More informed insight and understanding as to when a female gymnast is going through a growth spurt or pubertal gains will aim to take the bias away from late maturers and offer greater leniency.
Across high-level performance gymnastics, weight measurements were initially encouraged, but ethical concerns have meant organisations are steering away from those methods, preferring to use parents’ data as guidance.
“We don’t know if that’s the right thing or not at the moment,” admits Patel. “Having that prepubescent body has been influenced by other cultures, from the Russians and Chinese. But the sport has changed slightly. Within the Western culture, gymnasts are trying not to be rushed.”
Female gymnastics is becoming a lot more about power, with varying body types more acceptable than what would be previously desired. But changing attitudes, Patel says, remains slow.
Fundamentally, a shifting approach means altering a culture that has been inherent within the sport for years. As a consequence, bio-banding is primarily used as a tool to educate and spread awareness. There is evidence that shows pubertal growth impacts the brain’s ability to process information about body positioning and can adversely impact neuromuscular control, crucial to gymnastic performance.
“It’s just about working out how to engage and educate coaches,” says Patel. “The message is being ingrained but we’re probably at a point where we need to do more work.”
Horse racing — Kubler Racing
Sarsen Farm, Upper Lambourn, Berkshire — 70 miles west of London. It is 9am and the horses are making their way out of the barns and toward the fields. The Athletic is invited into Kubler Racing’s office — situated in a bespoke racing yard — where, if you peer through the back windows, there is a circular, treadmill-like revolver with horses warming up. Bio-banding, remarkably, underpins Daniel and Clare Kubler’s training and development of horses.
“Bio-banding, for us, is to use physiological markers in the horses to sort them into groups,” says Daniel.
(Jacob Tanswell/The Athletic)
Daniel and his wife Clare learned about Cumming’s work on social media, having already implemented a form of bio-banding themselves. Flat racing is age-specific, with horses competing from the age of two, first racing in age groups before facing older horses. Daniel and Clare found performances in two-year-olds largely tended to favour those born in January compared to, for example, those in May due to the additional period of maturation.
“People wouldn’t necessarily call it bio-banding,” says Daniel. “They would say is it a forward, backward or a mature horse? There is a big difference if a horse is born earlier in the year than in the middle of it. We found there was a bias towards horses born in February because you could get faster-maturing two-year-olds.”
Daniel and Clare began to look at the growth plates in a horse’s skeletal system, indicating what stage it is at in its maturity.
Daniel shows The Athletic X-rays of a horse’s knee joints (below), explaining the purpose of bio-banding in horse racing. How they group horses is largely influenced by these X-rays, which shows how physically developed a horse is.
“The bones will either be open, fused together or somewhere in between,” says Daniel. “We can then make a judgment. If the joint is closed, they’ll be ready to do more and push training levels. If they’re still wide open, they’re probably quite an immature horse, so there’s no real benefit to pushing them to train harder. You have to give them more time before they compete. We will do most checks on horses once or twice.”
Unlike humans, a horse’s cardiovascular ability is straightforward to train, but the skeletal system is the slowest part to adapt, meaning the formative years of a horse’s life are spent building up its physical load. “The risks associated with training an immature body means the animal goes too hard too soon,” adds Daniel. “Bio-banding is essentially about welfare.”
We venture out onto the racing track. The early maturers and older horses are going through speed work, having been put into groups to increase their training load. The week is mapped out to ensure Wednesday is a horse’s lighter training day, helping to lessen the load on their skeletal system.
“This horse is ready for more training”, says Daniel, pointing to one at the front. “So we will increase its training load appropriately.
(Jacob Tanswell/The Athletic)
Allowing a horse more time to mature means they are introduced to competitive racing and against older horses at a later stage. In short, bio-banding gives horses room to progress and not be judged as to whether they are effective racehorses in their first two years. If they do race, they will be grouped against horses two years or younger.
“Bio-banding is a useful tool to explain to someone ‘your horse is immature, here’s an X-ray of a mature horse — can you see the difference? This is why we need to give your horse a bit more time to develop’.”
Emerging evidence suggests bio-banding can be used as a supplementary tool in youth development — in both humans and animals — to challenge technical and physical skills and contribute to removing biases in selection.
It is, however, stressed that it is not to remove age-group sports but to operate as a complementary part of a sporting programme.
“Age groups are great if you want to match kids on factors that closely align with age,” adds Cumming. “Think about experience, time playing football, social development and cognitive development; all of those things follow much more closely to age rather than biological development.”
Bio-banding is not a novel or abstract idea, but its awareness and how to implement best practices is becoming prevalent across multiple sports and may well shape the future of athlete development.
Talent identification is changing and bio-banding is changing attitudes and removing biases. The hope is that early maturing athletes are no longer hamstrung or overlooked and are now able to develop at the rate equivalent to their biological age. Better, more structured practice will aim to challenge athletes of all bio-bands, relative to their strength and skill. It could ultimately shape and elevate talent development.
“So much research has been done about it,” concludes Brookman. “Lots of positive research as to understanding the impact of bio-banding and understanding the reasons why. Sport is now at a place where it’s not a secret anymore.”
(Design: Sam Richardson; photos: Laurie Lapworth/University of Bath))
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