When Katie Weatherston caught an edge and fell during a game of pick-up hockey two years ago, the Olympic gold medalist knew she had sustained another concussion.
Her head wasn't right; she felt foggy and dizzy. The symptoms didn't go away and Weatherston, a member of the team that won gold in Turin in 2006, lost her chance to make it to the Vancouver Olympics.
"I still get symptoms," the 27-year-old says. "I've been in the postconcussion phase for two years."
Evidence is mounting that women, who are more likely than men to suffer a sports-related concussion, also have more severe symptoms in the days immediately following the injury. But what about the months and years afterward?
That's what the University of Montreal's Dave Ellemberg and his colleagues are investigating. They say their research could point to a need for rule changes in women's sports and lead to gender-specific protocols to determine when it's safe for females to return to the rink or the soccer pitch.
"The current clinical assessment protocols and return to play guidelines, which are almost entirely based on research with male athletes, are not only inappropriate for women but likely place them at a greater risk of suffering multiple concussions and experiencing long-term consequences of their injuries," Ellemberg says.
Researchers in Canada and the United States say they don't know why women are more vulnerable to sports-related concussions, but factors may include weaker necks, subtle differences in brain chemistry, and differences in the way females are coached or train.
With almost $400,000 in funding from the Canadian Institutes of Health Research, Ellemberg's team is tracking concussed male and female university athletes for two years or more to compare their symptoms, cognitive deficits, impairments in balance and anomalies in the electrical activity of their brains.
Concussions occur when there is a rapid acceleration or deceleration of the head. The brain moves or rotates inside the skull and different parts of it move against each other. Symptoms include headaches, confusion, amnesia and sensitivity to light or noise and can last days, weeks or months.
The National Hockey League is under intense pressure to come up with rule changes to reduce the number of concussions, also known as mild traumatic brain injuries, which have been linked to dementia later in life.
Far less attention has been paid to women athletes.
But female university athletes in the United States who play soccer, basketball, lacrosse and hockey have a higher risk of getting concussed than their male counterparts, says Tracey Covassin, a Canadian researcher at Michigan State University who began to study concussions in female athletes a decade ago. She says it is still not clear how much greater that risk is, but Ellemberg says evidence suggests that women are three times more likely than men to suffer a sports-related concussion.
In 2005, a team of American researchers reported that female high school and university athletes were almost twice as likely as men to show cognitive impairment, such as slower reaction times, following a concussion.
The studies have all been with high school and university athletes. Researchers don't know if young girls are more likely to get concussions than boys.
There are hints in the scientific literature about brain differences between men and women that may somehow be related to concussions. Women generally take longer to emerge from a general anesthetic than men, Ellemberg says, and animal studies suggest the female brain is more fragile, at least immediately following an injury.
Ellemberg also suspects that differences in coaching and training play a role. For example, because there is no checking in women's hockey, girls tend not to practise how to take a hit. This may mean they are less able to brace themselves if a collision can't be avoided.
Covassin is involved in a large American study of high school and university athletes to see if females take longer to recover from a concussion than males.
There are risks associated with all sports and all kinds of physical activity, Covassin says, and no one wants girls or women to stop playing hockey, soccer or other sports. She suspects that female athletes are getting more concussions because they are stronger, faster and more aggressive than in the past. Women are also more likely to be honest about their symptoms, she says, since unlike their male counterparts, they don't risk losing lucrative professional contracts if they are injured.
But they do risk losing their shot at athletic glory.
Weatherston, who runs a hockey school for girls in the Ottawa area, had her first concussion in 2006 when she was cross-checked from behind during a practice and went into the boards head first. She couldn't play for three months.
Then, in December of 2008, came the minor fall that jarred her brain and killed her dream of Olympic gold in Vancouver.
"It was devastating not to play," she says.