Growth and Maturation in Soccer Academies | Sean Cumming, Xabier Monasterio & Alberto Fílter - FSI Talks #15

A player's biological maturity can be the difference between being released and becoming a professional. In youth football, assessing talent without accounting for each player's growth rate is one of the most common — and costly — mistakes academies make.

In episode fifteen of FSI Talks, Alberto Fílter, coordinator of FSI Lab, speaks with Dr. Sean Cumming, professor at the University of Bath and an internationally recognised expert in growth and maturation in sport, and with Xabier Monasterio, physiotherapist at Athletic Club and lecturer at the University of the Basque Country.

Together they explore how differences in biological maturity affect performance and player selection, and what strategies academies can implement to make fairer and more accurate decisions.

Chronological age vs. biological maturity in football

Two players in the same age category can have radically different physiological profiles depending on their biological maturation rate. This gap — which can be equivalent to several years of physical development — distorts the assessment of real talent in football academies.

Chronological age measures the time elapsed since birth and forms the basis of traditional categories: under-12, under-15, under-18. However, it does not reflect the actual physical development of each player.

Biological maturity, on the other hand, measures how far the body has progressed towards adulthood. Within a single under-15 category, there can be players with the physical profile of a 12-year-old alongside young men who already have the body of a 17-year-old footballer.

This gap creates clear competitive inequalities and can lead to talented players being released simply because their physical development is slower.

Methods for assessing biological maturity in football academies

Elite academies are incorporating biological maturity monitoring systems to make more informed training and recruitment decisions. The most widely used methods are the following.

Height and weight tracking

Regular monitoring of height and weight is the most accessible and widespread tool in youth football development. The Premier League applies it systematically across all its academies.

Although it does not directly measure biological maturity, it provides a low-cost functional indicator that allows significant changes in player development to be detected throughout the season.

Skeletal maturity assessment

Skeletal maturity is determined through wrist X-rays, which allow the state of bone development to be analysed with great precision.

It is the most accurate method available, but its financial cost and radiation exposure limit its use to occasional assessments rather than regular monitoring.

Peak height velocity (PHV)

Tracking peak height velocity, known as PHV, is the method that provides the most practical information for training management. It involves measuring growth rate every three to four months to identify the exact development phase of each player.

Knowing when a player is at their growth peak allows coaches to anticipate injury risks, adjust training loads and avoid hasty decisions about their potential.

How growth affects performance: the awkward phase

During periods of accelerated growth, many players experience a temporary drop in their technical performance. This phenomenon is known as the awkward phase and occurs because the body grows faster than the nervous system can adapt to its new physical configuration.

Studies conducted at Southampton FC's academy have documented this temporary decline: players lose fluency in movements they previously mastered, and coaches may perceive it as a regression in their level.

However, once growth stabilises, performance not only recovers but surpasses previous levels. Releasing a player in the middle of their awkward phase is one of the most costly mistakes a scout can make.

Biobanding: grouping by biological maturity instead of age

Biobanding is a strategy that groups players according to their biological maturity level rather than their chronological age. Academies such as Athletic Club are already applying this approach with positive results in talent assessment and development.

The main advantages of biobanding include:

• Eliminates extreme physical mismatches that distort the assessment of real talent
• Forces physically advanced players to rely on technique and tactical intelligence rather than just their physical advantage
• Allows late-maturing players to develop in an environment where their potential is not overshadowed by their size
• Reduces early dropout among players with high potential but slower physical development

At the same time, biobanding presents an interesting challenge for early maturers: unable to rely on their physical advantage, they are pushed to develop technical and tactical resources that might otherwise remain untapped.

Adapting training to each stage of growth

Elite academies have introduced individualised load protocols based on each player's maturity phase. The goal is to maximise development without increasing injury risk during the most vulnerable periods.

The most widely applied strategies include:

• Reducing training volume during rapid growth periods to avoid muscle overload and apophyseal injuries
• Incorporating strength and coordination work to compensate for temporary coordination loss and strengthen stabilising muscles
• Measuring PHV every three to four months and proactively adjusting planning according to the development phase
• Identifying early discomfort in bone growth areas and acting before symptoms become chronic

A player at peak growth should not be assessed using the same criteria as one whose development has stabilised. Doing so means comparing two completely different physiological realities.

Growth-related injuries in young footballers

Accelerated growth significantly increases the risk of specific injuries related to bone development zones. The apophyses — the points where tendons attach to growing bone — are particularly vulnerable during PHV.

The most common injuries in players going through a growth peak include Osgood-Schlatter disease at the knee and Sever's disease at the heel. Both are directly linked to the mismatch between bone growth and the adaptation of soft tissues.

Continuous PHV monitoring allows the coaching staff to anticipate these risks and adjust training loads before the first symptoms appear.

Biological maturity as a strategic factor in football academies

The conversation concludes by highlighting that integrating biological maturity monitoring into an academy's methodology is not just a health issue — it is also a competitive advantage in talent identification and development.

Academies that assess players with biological maturity in mind make fairer recruitment decisions, reduce injuries and make better use of each player's potential.

Biobanding, PHV tracking and individualised load adaptation are tools that are already available. The question is no longer whether they are worth implementing, but how much talent is being lost in academies that still have not.