American football is notorious for causing head injuries, but there's another sport that reports even more concussions: Women's ice hockey.
In a 2015 NCAA survey, it was found that female hockey players report concussions more often than male football players, and previous studies have found women's hockey to be on par with concussion rate in men's wrestling, football and hockey.
So why do women who play hockey have such a high rate of head injuries?
A new Vox video, released during the 2018 Winter Olympics, explains why.
Compared to American football, ice hockey is faster, involves more collisions and is played on a harder surface - all of which goes a long way towards explaning why concussions are so prolific in the winter sport.
Yet the explanation for why women report more head injuries than men is less intuitive.
According to all the experts interviewed by Vox, when men and women play the same sport, like soccer and basketball, female athletes report higher concussion rates than male athletes.
There are several factors that may feed into this phenomenon. For instance, female athletes are generally more knowledgable about concussion signs and symptoms, so they know when they need to report one.
There might also be biological factors involved, including hormones, strength of neck and the structure of nerve fibers, although research in this area remains young and inconclusive.
When it comes to ice hockey, style of play is also a factor. For instance, unlike men's ice hockey, female players are not allowed to "check" others with their bodies. This means that while male ice hockey players prepare more for contact, female players focus less on contact and more on skill and speed, leaving them vulnerable to concussions.
Still, it may have nothing at all to do with susceptibility. Compared to their male counterparts, female athletes may just be more likely to report head trauma.
"So it may not be the fact that men are sustaining less concussion than women," said Zachary Kerr, head trauma researcher and author of the NCAA survey.
"Maybe women have a better knowledge of concussions. Perhaps we as men are more stubborn with our healthcare. Women are more likely to disclose issues in general and we are just seeing that transferred over to the topic of concussions."
A lot of this has to do with social bias. Thanks to social, cultural and gender biases, men are considered stronger, more aggressive risk-takers, whereas women are told to follow the rules and play it safe.
Gender stereotypes become a problem when those who report head trauma are ridiculed for being weak. Far from celebrating athletes who make smart decisions about their body's health, we applaud athletes who push through the pain and play even when they shouldn't be.
Regardless of the true underlying factors, the data clearly shows that female athletes, and female ice hockey players in particular, are at great risk of head trauma.
Until the research catches up and science reveals more about female and male concussion rates, steps must be taken to protect female athletes from undue injury. Just like we do for men.