The end-of-August announcement that the National Football League will pay $765 million to settle a lawsuit involving thousands of its former players over problems related to head trauma is just one sign of the growing concern that the sport’s collisions pose a serious risk to long-term player health. But little is known about how a season of head hits affects the largest group of football athletes: the nearly 4.5 million youth and high school student players.

A study by researchers in North Carolina and Virginia is addressing this gap with the most comprehensive look at the relationship between impacts and injuries in players from ages 6 to 18. By combining biomechanics, brain imaging, and neurological testing, the team could develop tools to identify when a player has been hit hard enough, or repeatedly enough, to risk a concussion or other brain injury. In July, the researchers reported a new way to calculate head injury risk over a season based on data from accelerometer-equipped helmets. The researchers also used brain scans to examine those same players to search for links between measured head impacts and changes in brain tissue and function. Those results are still being analyzed.

Around one million Americans play high school football, and more than three times that many play in youth leagues. While athletic trainers and physicians stand on the sidelines of professional and college games, high school and youth players often depend on coaches and parents to watch for problems. “The younger that you get in football, the more people you have playing and the less attention paid to having medical personnel present at the games to assess function in players,” says Joel Stitzel, chair of biomedical engineering at Wake Forest Baptist University School of Medicine and an investigator in the study.