For many English footballers, the journey to a place on the national team begins in Premier League football academies. But home-grown talent doesn't always rise to the top.
Players like David Beckham and Steven Gerrard were part of England's 'Golden Generation', but failed to deliver international trophies. As that generation slips into retirement, the country is searching for new talent.
The 2014 World Cup squad featured promising young players like Adam Lallana, Raheem Sterling and Ross Barkley. But the team slunk out of the competition after three matches, two goals and placing last in the group.
English players account for less time played in their top home league than their German and Spanish counterparts.
Both the Premier League and its fans are keen to nourish a new generation of talented home-grown players.
But we may be missing out on some of our best potential talent.
Late developers like Lionel Messi and Diego Maradona have become some of the most successful players of all time. But for many talented footballers, a slow start for puberty can mean they struggle to succeed in the academy system.
Late bloomers struggle to catch up
Teenagers mature at different rates, and children of the same age can vary greatly in biological maturity.
When young footballers are 12 to 15 years old, the difference in physical maturity between players is at its widest. Early-maturing boys are almost adults, while late-maturing boys are still in the initial stages of puberty.
With strength and speed on their side, early maturers have a major advantage as clubs decide which young players will make the cut.
Countries who prize technical skills over physical styles of play are less likely to favour early maturers. But the physical nature of the English game means late bloomers struggle compared to their larger peers.
Strength and speed aren't the only advantages of early puberty. Players are spotted earlier and experience success more often. They receive more support, encouragement and access to coaching and training resources. They also have the opportunity to compete at the highest levels.
And late developers aren't just at a physical disadvantage, but a psychological one. Facing down one of their fully-grown peers on the pitch, a smaller player can doubt their own ability to compete.
The focus on physical ability can also be a disadvantage for early-maturing footballers. Coaches and scouts may believe that early physical advantages will carry on through adulthood. This creates unrealistic expectations for a young player's potential.
By age 18, physical differences between players have usually evened out. Late developers can eventually overtake their peers in physical tests and technical skills. The physical challenges they face early on can make them stronger technically and psychologically. Early maturers who focused on strength over technique find they can't compete with more balanced players.
But by this point, many talented players have already missed their shot at the stadium. And England may have missed out on its own Messi.
Understanding player potential
For all players to have the best chance to reach their potential, understanding growth is key. Clubs must consider maturity when making decisions about training, competition and team selection.
Dr Sean Cumming is a senior lecturer in our Department for Health. He researches growth and maturation in young athletes.
Sean works with the Premier League's James Bunce and Dan Hunt to support the Elite Player Performance Plan. The Plan aims to improve the selection, training and development of academy players.
Clubs have to make decisions based on attributes which young footballers haven’t yet developed. Being able to predict each young player's true potential is essential.
Sean leads a scientific advisory group of leading researchers and practitioners in the field. He has helped the Premier League establish guidelines and procedures for assessing and monitoring growth and maturation in youth footballers.
How bio-banding creates a more balanced competition
Sean has also helped enhance the league’s Player Management Administration (PMA) database. Academies can use the PMA to track and account for differences in growth and maturation when evaluating players. It monitors about 5,000 young footballers across the academy system. The system assesses players aged nine to 17 on growth, fitness and performance throughout their early careers.
The PMA also allows academies to group players for training and competition by biological age, not chronological age. This uses a process called bio-banding, which was first introduced in youth rugby. By matching training and competition to the athlete’s level, practitioners can optimise development and reduce injuries.
Sean recently helped the Premier League organise the world’s first bio-banded tournament. Southampton, Stoke City, Norwich City and Reading football clubs all participated. The players were between 11 and 14 years old, but competed against players of the same maturity level. Initial feedback suggests it was successful for players and coaches, with further analysis underway.
Late-maturers had the chance to use their technical skills, play creatively and take on leadership roles. Early-maturers found the competition more physically challenging, so they had to work harder and rely more on their technical abilities.
Once a club better understands a player's maturation, they can tailor their training.
One option is holding late developers back in a younger age group, so they can compete against players at the same maturity level. Sean has acted as an independent judge in such cases, looking at a player's height, weight and other development indicators. If he discovers the player is a late developer, he may recommend the Premier League holds them back.
Creating a new standard of footballer
Sean is also working with the Premier League to develop fitness standards based on age and maturation rate. This will allow clubs to better evaluate player ability and potential. The project aims to increase the number of home-grown players in the Premier League.
Clubs can use these standards when they make decisions about young footballers. By assessing talent through the lens of maturity, clubs can understand a young player's true potential.
The project will show how growth and maturation contribute to footballers' development and the academy selection process. It will determine how training and conditioning programmes impact player fitness beyond what can be expected from normal development.
The research has also contributed to educating staff working with young players. Over 120 practitioners across 29 academies participated in workshops about understanding growth and maturation. They can now give players the best training and conditioning for their rate of development.
Now today's small but gifted young players could develop into tomorrow's Premier League stars and World Cup winners.
Taking bio-banding beyond football
Bio-banding could benefit players and clubs in other sports too.
Sean is now spending a day a week with Bath Rugby at their academy as part of a six-month project, working with Mark Atkinson and England rugby legend Danny Grewcock. The project aims to bring the benefits of bio-banding to the development of young rugby players and contribute to the club's continuing success at nurturing new talent. A Proximity to Discovery grant from the Medical Research Council makes this work with the club possible.
By understanding growth and maturity, we could see the potential of young athletes across all sports - and help them live up to it.