Science of Sports Stars
How Bath is finding future champions, reducing injury and helping young athletes reach their full potential.
Harry Kane is the all-time top goalscorer for Tottenham Hotspur and England, but the final whistle was almost blown on his career when he was just 12 years old. Later, former Arsenal academy boss Liam Brady admitted to releasing the budding footballer for being “a bit chubby”.
“I was definitely a late developer,” Harry told OneFootball. “I didn’t physically develop until I had a growth spurt around 15 years old and caught up with some of the other guys in the age group... it took me until probably 21 until I felt like I was physically in really good shape.”
He was one of the lucky ones, and was eventually picked up by another club – but how many other would-be superstars have slipped through the net before realising their true potential? There isn’t a “crystal ball”, the ex-Gunners chief grumbled.
No, there’s something better: biobanding.
Professor Sean Cumming from our Department for Health is an internationally recognised sports scientist and expert in growth and maturation. He’s implemented a clever method of calculating how tall a child will grow in the future by using their current height and weight, date of birth and their parents’ height.
“By knowing what their future height will be, we can assess how physically developed they are for their age and sex at any given point in time,” says Sean. The children are then grouped by their physical maturity rather than their age – levelling the playing field among budding athletes by giving the smaller, later developers a chance to shine, and challenging the bigger, early developers in a way that supports their progress, too.
“We know from the data that smaller kids will eventually catch up and there won’t be any differences between early and late developers. Often, they end up being taller as adults as they grow for a longer period,” he adds. “The problem is, if you’re trying to identify the best talent at say 13, you’re going to go with the early developers every time because they’ve won the genetic lottery of being the first to obtain the physical and athletic advantages of puberty.”
Game, set, match
Development varies so much during adolescence that there can be as many as six years’ biological difference between children of the same age – giving those taller, stronger and bigger early developers the upper hand in most sports. In the long term, however, this could be their downfall if they’re not stretched enough in their development. The Lawn Tennis Association (LTA) grew wise to the problem, and enlisted Sean’s help in 2015.
“The LTA had noticed the top kids in every age group, for both boys and girls, were the tall, early developing kids,” he explains. “There were some 12-year-olds who were over six foot [1.82 metres] who were excellent tennis players, but once they stopped growing and the other kids caught up, the coaches realised it was just a temporary advantage.”
Sean set up systems of measuring and monitoring players’ growth and the bearing this had on selection biases. What he found was that a bias towards early maturing boys started aged 12, while for girls it was around nine because puberty naturally starts earlier for them. Despite late developers making up 15% of the population, they had little representation as players progressed through the system.
“For sports such as tennis, being taller than the opposition is going to offer a major advantage,” says Sean, “but imagine a 10-year-old girl who’s five foot five [1.67 metres] – it’s tall for that age group, but it’s incredibly small for an adult female tennis player. So these girls weren’t developing the kind of game they’d need in the future in order to be successful.”
Biobanding isn’t a new phenomenon, as Sean points out. It’s been used in combat sports such as judo and boxing, where age and weight are considered for children’s safety, for decades. But this was the first time it had been used to address selection bias.
Hearing of Sean’s work with the LTA, the English Premier League got in touch wanting to tackle the same issue. Director of Football Development Ged Roddy, former head of Team Bath, was developing the Elite Player Performance Plan to nurture a new generation of homegrown talent at a time when clubs were heavily investing in international players.
“Ged sat down with the academy heads and they all agreed they had problems with growth and maturation,” Sean explains. “They didn’t know how often to measure it, the best way to measure it or how to interpret that data, but they all had this belief that they were investing in big, early-maturing boys and potentially losing out on some later-developing talent.”
Sean and colleagues launched a screening project, measuring the players every three to four months. Not only did this data tell them whose biological clock was late, early or right on time, it also, crucially, meant they could tell who was going through a growth spurt and at greater risk of injury.
“Children usually grow relatively steadily, about five centimetres a year, and it’s all in the legs and arms,” explains Sean. “In puberty, the growth is in the torso and during a growth spurt, they can grow ten, sometimes 20, centimetres per year, so it can be really quite rapid.”
“We ran workshops across the country,” he continues, “educating sports scientists and medical staff on how to effectively measure and understand child development. At the same time I was delivering educational workshops on growth and maturation for the academy coaches on behalf of the English FA. Suddenly, we started seeing clubs make decisions based on growth and maturity. They started biobanding.”
Scoring results
The world’s first youth biobanded football tournament kicked off in 2015 between the youth academies for Reading, Stoke, Norwich and Southampton – the latter also trains here at the University of Bath. Players were matched by maturity rather than age, seeing some ‘playing up’ with older children and others ‘playing down’.
Without their physical advantages, early maturers had to find new ways to succeed. They had to think faster and release the ball quicker. For the late developers playing against younger children, they had the opportunity to command the game and show the coaches their skills. For Sean, it was a chance to find out what the players really thought.
“What we found was that both the earlies and lates loved the concept for completely different reasons,” he tells us. “The earlies came back saying, ‘It was difficult, but it was a better learning environment – the older boys were mentoring me, and I was making friends.’
“The late developers were saying, ‘Yes, it was less of a challenge’, but they had a chance to demonstrate their abilities because even if technically, tactically, and psychologically they might be the better athlete, sometimes they just can’t compete [against larger players].
"For those players to survive the system, they have to be off-the-charts and when they eventually come through as the best player, the last thing clubs want to see is them in the opposing team.” Like Arsenal losing Harry Kane to Tottenham.
In recent years, Arsenal has worked closely with Sean to implement biobanding. Their academy’s former Head of Sports Medicine and Athletic Development, Des Ryan, has spoken of how such insights helped identify talent such as Eddie Nketiah, who currently plays for the first team, and Folarin Balogun, who recently joined Monaco for €40 million.
“They were classic late developers who often struggled when they were going through their growth spurt as well,” explains Sean. “Because the coaches knew where they were in their development, they were much more capable of managing them effectively.”
Des adds: “Sean was a great support to me and the team at Arsenal Academy. It resulted in aligned assessment and interpretation of growth and maturation in Premier League academies.
"It helped us understand the individual better and thus provide a high level of support. There are numerous examples of how we helped players in the context of them being early, on time and late developers, the excellent support and education from Sean.”
Des is currently Director of Sport and Physical Wellbeing at the University of Galway and Chairperson of the Gaelic Games Athletic Development working group, bringing these insights and experiences to the sporting community in Ireland.
"The expertise available at the University of Bath has provided a valuable resource to the Premier League and its Clubs"
Matthew Green, Head of Elite Performance at the Premier League
Exercise restraint
An important part of managing athletes’ development is monitoring growth spurts and adjusting training programmes to reduce injury. Sean explains: “We know that if a kid is at 85% of their future height, their growth spurt is about to take off and that at 90%, they’re growing incredibly rapidly, with bones growing quicker than muscles and tendons. That’s when injuries like Osgood-Schlatter’s and Sever’s disease come in.”
To prevent this, Sean and his University of Bath colleague, Dr Sean Williams, work with clubs to tailor their training programmes, swapping intense sessions for ones focused on improving mobility and building core strength. The results have been remarkable.
“We worked with AFC Bournemouth for a year and by swapping one training session per week for players going through growth spurts, we reduced injuries by 70% and the amount of training time lost by more than 90%."
He continues: "Injuries can have a huge impact on an athlete’s future career. You’re not getting the chance to train and develop, and you’re more likely to pick up future injuries. We have a number of PhD students starting with the Scottish FA and Manchester City who will be investigating this.”
Other sports are reaping the benefits of biobanding, too. Sean’s past PhD students, Dr Siobhan Mitchell and Dr Tejal Sarika Patel, carried out research in ballet and gymnastics, respectively, where the selection bias is reversed.
Lower body fat and a longer leg-to-torso ratio are traditionally favoured, and as formal selection strategies coincide with puberty, those who mature earlier may not make the cut, while those who mature later experience increased training and testing at a time when they’re growing rapidly. Both can be harmful physically and psychologically.
Siobhan said of her findings: “Those who more readily conform to the physical, social and psychological ideals are the dancers who tend to progress. Young dancers can enter full-time, vocational training from when they are just 11 years old, training up to six days per week. As a consequence, differences in the timing of maturity have important implications for health, talent identification and development.”
Working with the national bodies, One Dance UK and British Gymnastics, they developed education resources on how to support athletes during those crucial points in their development. “We want children to grow into healthy adults,” Sean adds, “because most aren’t going to be professional sportspeople and we want to make sure we’re looking after them.”
Biobanding might seem like a no-brainer, but there has been some pushback from sports psychologists. “There was some criticism that biobanding would ignore psychological development, but that isn’t the case at all,” he explains. “Clubs such as Southampton actually align their psychological support for the boys based upon whether they are playing up or down.
“The big, early developers are taught how to cope with failure, which will be an important skill in the future when they don’t have the physical advantage anymore. In contrast, the late developers who are playing down are taught about leadership and mentoring. We’ve seen the same benefits for girls, having worked with US Soccer.”
As Sean is keen to point out, biobanding isn’t a replacement for age groups, but an additional part of the programme that exposes young athletes to new challenges, helps them reach their goals and reduces risk of injury. Wouldn’t it be great if it were introduced in schools, too? Sean thinks so.
In partnership with the charity Podium Analytics founded by former F1 boss and Bath honorary graduate, Ron Dennis, the aim is to apply what’s been achieved with the Premier League and share that knowledge and understanding with schools nationwide.
“We’re creating a free, online educational programme that all schools can access,” says Sean. “The hope is that young people – not just those in performance pathways – benefit from fairer opportunities in sport.”
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