Karolina Urban remembers most of the game. It was the last of her 2008-09 season. As captain of the University of Toronto women’s hockey team, she followed the puck on the ice. “The puck popped out and I got it,” she said. “The girl … just smoked me so hard that I twisted in the air before I landed.” That was Urban’s first concussion. She has suffered two since. They haven’t discouraged her.

Coach Mike Babcock claimed that in order to beat the Russians, Ryan Getzlaf, Dan...