Title IX has provided females in the United States with equal opportunity in athletics.

In terms of gender equity, however, high school girls appear to be getting more than their share when it comes to concussions.

Experts in the field of head trauma can't fully explain it, but young female athletes have a higher rate of concussions than do their male counterparts.

Football players, as you might expect, have the highest rate on concussions among all athletes, but girls who play soccer have a higher rate than their male classmates who play the same sport. The same goes for basketball and softball/baseball.

A study published in "The American Journal of Sports Medicine" found that girls suffered twice as many concussions as boys in similar sports.

Welcome to the unfairness of fairness.

Some experts believe that boys suffer fewer concussions because they have heavier muscles in their neck and upper torso. They are better able to absorb blows to the head or are less likely to have their heads snapped back by a collision.

Some researchers have suggested that the difference lies in perception, not anatomy.

As a society, we may be more protective of girls than boys and therefore more cautious in allowing girls back onto the field after a head injury, suggested Dawn Comstock, an assistant professor at the Ohio State University College of Medicine in Columbus.

"Boys have to be tough and learn to play through pain, so they will be less likely to report a concussion," Comstock suggested.

Another expert theorizes that girls may self-report concussions at a higher rate than boys, thereby skewing test results.

"Women may be more honest in admitting that they've had post-concussion symptoms," Dr. Robert Cantu of Brigham and Women's Hospital in Boston told The New York Times.

Dr. Kathleen O'Brien, who practices sports medicine and pediatrics at the Alfred I. DuPont Children's Hospital in Wilmington, Del., is not ready to embrace any of the theories.

"We need to sort through this a little more before we can make any blanket statements," she said. "I don't know that we should jump to any conclusions."

Indeed, research in the entire area of concussions is in its infancy; much is not known about the injuries or their most effective treatment.

"If you look back over the past five years at what we've learned, it's been remarkable," O'Brien said. "It seems like what we're doing now is vastly different than what we were doing 10, 15, 20 years ago. Our knowledge base continues to expand and evolve."