She may have retired from soccer, but Brandi Chastain has never stopped looking for ways to contribute to sports. Recently, that's meant collaborating with Chris Nowinski, executive director of the Concussion Legacy Foundation.

Chastain, a member of the 1999 World Cup-winning U.S. women's national soccer team and a prolific header of the ball, has decided to donate her brain to the foundation after her death, where it can be examined for signs of trauma.

Emerging scientific research has revealed the effects that repeat head trauma may have on the brain, but it's been focused on men's sports such as football, where Chronic Traumatic Encephalopathy -- a progressive degenerative disease -- has been posthumously diagnosed in dozens of former NFL players.

However, women have historically participated in contact sports less than men, so Chastain's donation is intended to raise awareness of female concussion risks, even in technically non-contact sports such as soccer, hockey and basketball. It's in those sports where women are more likely than male athletes to sustain a concussion.

And Chastain's donation could provide valuable information whether or not she developed the proteins that can lead to CTE.

"Brandi Chastain's decision to donate her brain to further research is a powerful and courageous act that will ultimately improve the future health of female athletes, military veterans and other women who experience repetitive brain trauma," said Ann McKee, a professor of neurology and pathology at Boston University, in a statement released by the foundation. "We currently know so little about how gender influences outcome after trauma; her pledge marks an important step to expand our knowledge in this critical area."

Research shows women and girls are more easily concussed than their male counterparts. However, scientists don't yet understand the long-term effects these injuries have on the female brain. Only seven of the 307 brains donated to the VA-BU-CLF Brain Bank -- which is overseen by McKee -- have been women's, and none were found to have CTE.

"I'm part of asking, why are we more susceptible to this?" said Chastain, who is part of Safer Soccer, a piece of the foundation that promotes the benefits of delaying the introduction of headers in youth soccer. "If I could help get to the bottom of this, that's great."

She made the decision to donate her brain after she and Nowinski discussed what her own personal legacy might be.

Chastain (left) and Canada's Charmaine Hooper head the ball during their semifinal match in the Women's Gold Cup Tournament game in Louisville, Kentucky, in July 2000. JEFF HAYNES/AFP/Getty Images

"I have been so fortunate in my lifetime to have participated in soccer with amazing people," Chastain said in a phone interview. "I've had incredible life experiences. And our team from '99, and the teams just before and after, was a really inclusive, proactive group trying to make a difference in the game."

There are several possible factors leading to a higher concussion rate in females, said Elizabeth Pieroth, a neuropsychologist and the associate director of the sports concussion program at NorthShore University HealthSystem. Women's neck muscles aren't as strong as men's, which could affect the way a female head sustains contact. Hormones may also play a role, and there is discussion of whether testosterone in men has a protective effect on the brain.

There also may be cultural factors, Pieroth said. Women and girls sometimes have fewer opportunities to play sports after college, meaning they could be more willing to self-report a head injury because the time needed to recover isn't perceived negatively, she said. And yet, Pieroth stressed, in the patients she sees, women and girls are just as motivated by the desire to help their teams when they become injured, and not to let down their teammates.

"There's not enough research on female athletes," Pieroth said.

Chastain also wants to spark a conversation about whether girls and boys should be learning to head the ball before a certain age.

Chastain said it's impossible to ask children at age 8 to 9 to self-report symptoms they may not understand. These children are getting faster and stronger and better at soccer, but adults still need to insulate them from the potential for long-term damage from head injuries.

"When I was growing up, no one was talking about concussions and what it meant," Chastain said.