Differences in training may also be a factor. Ingersoll explains how in ice hockey, for example, men are allowed to body check opponents whereas women are not. As a result, men practice checking in scrimmages and become accustomed to that style of play. Women are less prepared to be smashed against the ice because it doesn't happen as often.
From an anatomical perspective, men have stronger and more developed neck muscles, allowing them to better absorb a blow to the head. "Because girls' neck muscles are not as developed, they may be at a higher risk and may suffer more serious concussions," says Comstock.
Cultural factors might also explain the differences in concussion rates. "Coaches and parents may be more sensitive to injury in the female head," says Ingersoll. "Culturally, it may be OK for girls to talk about a concussion. Athletes who play tough, macho sports may not be as open to talking about a concussion."
Comstock agrees. "As a society, we protect girls more than boys. Boys have to be tough and learn to play through pain, so they will be less likely to report a concussion."
Researchers were most concerned about the fact that concussion rates in general are increasing in high school sports.
"It appears that concussion rates are increasing in high school sports," says Comstock. "We found that they account for 9 percent of all high school athletic injuries. A decade ago, concussions caused only 5.5 percent of all sports-related injuries."
A couple of other factors may also explain the overall rise in concussions. It may be that high school kids are bigger, stronger and faster these days so that collisions between players are more forceful and dangerous.
It may also be that athletes and coaches are doing a better job of documenting them.
"More athletes, coaches and athletic trainers are more aware that concussions are a serious injury," says Comstock. "That's good news, because concussed athletes will be more likely to receive medical attention."
To further protect young athletes from serious injury, researchers recommend educational programs, improved protective equipment and better enforcement of rules.
"We need to make sure athletes, coaches and parents are aware that concussions are a serious injury," Comstock says.
Says Ogborn: "Parents and coaches and primary physicians should all know the definitions of concussion, the signs of continued post-concussion syndrome, the guidelines for return to normal activity ... and the signs that should keep an athlete out of play for the entire season or longer."
And although more research is needed, concussion prevention may eventually be tailored for different sports.
"The more we understand the differences between male and female sports, the more we can do to address them," says Ingersall. "We need to focus prevention efforts on a case by case basis. For example, in soccer, goalkeeping causes more concussions in men, whereas defending causes more concussions in women. We need to look at the rules, the training and the technique for these positions."