High school football players with loose-fitting helmets have the highest rates of concussion, according to study being released this week at the American Academy of Orthopaedic Surgeons annual meeting.

Players with ill-fitted helmets also are slower to recover, according to the study that looked at data collected over nine years on more than 4,500 athletes who suffered their first concussion.

“Concussions are very complicated injuries, but (loose helmets) could be one more risk factor for experiencing more severe concussions," said study author Dr. Barry Boden, a sports medicine specialist at The Orthopaedic Center in Rockville, Md.

SEE ALSO: College team’s weekly helmet checks set a strong example for all levels

SEE ALSO: Learn more about USA Football’s Heads Up Football program

This news comes as no surprise to the 6,500 youth organizations and 1,100 high schools that signed up for USA Football’s Heads Up Football in 2015. Proper helmet and shoulder pad fitting have been a pillar of the health and program since its launch in 2012.

USA Football educates coaches, players and parents on how to properly fit helmets and shoulder pads to reduce the risk for injury, including concussions.