Study reveals six-year biological age gap in young football players

A major football study has found players of the same age can differ biologically by up to six years, raising concerns about fairness in youth development.

Researchers assessed over 1,000 academy players in Scotland’s Club Academy Scotland system, collecting birth dates, current height and weight, and parental height to estimate biological maturity.

The study, carried out between January and April 2024 by the University of Bath and the University of Edinburgh, was commissioned by the Scottish Football Association.

It found that only 80 per cent of boys were developmentally aligned with their calendar age. In one case, a 13.8-year-old had a biological age of 12.3, while another player aged 15 measured biologically at 18.

Late developers – who make up around 15 per cent of the population – were vastly underrepresented in the academy system, confirming a strong bias towards early-developing players.

Professor Sean Cumming is lead researcher from the Department for Health at the University of Bath.

The researcher said: “Academies are often populated by players who have simply matured earlier,.

“This project and the new pilot rule allow us to create more equitable environments for all players to thrive – especially late developers, who are typically underrepresented.”

Based on the findings, the Scottish FA has introduced a pilot policy allowing clubs to group players by biological rather than chronological age.

The aim is to give later-developing players a fairer environment to build confidence and develop their skills among similarly developed peers.

The pilot was announced at the Growth and Maturation Workshop at Hampden Park, where researchers presented the data to clubs and academy staff.

Steve Curryn, Scottish FA PhD researcher from the University of Bath, said: “Only around 80 per cent of boys were developmentally aligned with their calendar age.

“Some players in the same age group differed biologically by up to six years.

“This discrepancy can profoundly impact how players are perceived, selected, and coached.”

The pilot lifts the previous cap of three players who could be moved across age groups, allowing a more tailored approach to long-term athlete development.

Mark Leslie, sports science and data manager at the Scottish FA, said: “The University of Bath’s expertise has provided us with an unprecedented insight into growth and maturation in elite youth football.

“We’re confident this research will have lasting impact not only in Scotland but across global talent pathways.”

The next phase of the project will explore links between growth and injury in academy football.

Selected CAS clubs will track injury rates alongside growth and maturation data to better understand risk during periods of rapid development.

Using this data, the University of Bath will help design and deliver a growth-spurt-specific injury prevention programme.

This will include adjusted training loads, skill-based progressions and individualised strength and conditioning.

The programme is based on a pilot at AFC Bournemouth, where injury rates fell by 86 per cent and injury burden dropped by 90 per cent.