If you thought that boys playing football had the highest rate of concussion in high school sports, you guessed wrong. That dubious distinction is owned by soccer-playing girls.

Not only that, high school soccer girls' concussion rate is significantly higher than their football-playing counterparts, according to a study out of Northwestern University’s Feinberg School of Medicine.

“While American football has been both scientifically and colloquially associated with the highest concussion rates, our study found that girls, and especially those who play soccer, may face a higher risk,” said Wellington Hsu, MD, lead author of the study. “The new knowledge presented in this study can lead to policy and prevention measures to potentially halt these trends.”

All told, around 300,000 American teens suffer high school sports-derived concussions annually. That number is bad enough, but it gets worse when you understand that children and adolescents have less resistance to brain damage than adults – what neurologists refer to as “less cognitive reserve.” Consequently, concussions pose a greater risk for more severe symptoms. These may include loss of memory, confusion, headaches, dizziness, and a more prolonged recovery.

Northwestern U's research examined a sample of injury data from 2005 to 2015 from the High School Reporting Information Online injury surveillance system. This period covered the years before the enactment of traumatic brain injury laws addressing training, return to play and liability (2005-2009); and the years when laws were in effect in all 50 states and the District of Columbia (2010 to 2015). The sports tracked were soccer, basketball, wrestling, baseball and football for boys; and softball, volleyball, basketball and soccer for girls. The database included detailed information on each player their injury, the mechanism of injury, and the situation that lead to the injury.

The study notes that while overall participation in the high school sports tracked increased by 1.04 fold from 2005 to 2015, the number of correlated injuries increased by 2.2 fold. Girls volleyball and boys baseball had the largest increase in the rate of concussions during the decade-long study period.

The researchers believe that girls may face a greater risk of concussions and lesser injuries in soccer due to a lack of protective gear, the emphasis on in-game contact and the practice of hitting the ball with one's head.

The research was presented at the 2017 Annual Meeting of the American Academy of Orthopedic Surgeons.