The toll taken by five other sports, including soccer and baseball, is also broken out in the study — as well as what steps could be taken to help prevent such potentially devastating injuries as concussions, brain contusions and brain hemorrhages.
"Studies up until now really haven't put a lot of focus on the reason why children and youth are getting brain injuries in sports," said principal researcher Dr. Michael Cusimano, a neurosurgeon at St. Michael's Hospital in Toronto.
"And if we're going to keep people in sports, which has tons of benefits to it, we need to understand why they're getting hurt.
"If we understand why they're getting hurt, we can develop means by which to prevent them and make the sport relatively safer."
The study looked at almost 13,000 injured children aged five to 19 between 1990 and 2009, using data from the Canadian Hospitals Injury Reporting and Prevention Program (CHIRPP), which tracks visits to emergency rooms at 11 pediatric hospitals and three general hospitals across the country.
More than 80 per cent of children and teens with brain injuries were male, with an average age of 13.
Researchers found that hockey accounted for 44.3 per cent of all brain injuries, with almost 70 per cent of them occurring in children 11 and older as a result of player-to-player contact or being hit into the boards.
Surprisingly, said Cusimano, young hockey players are still getting hurt because of being checked from behind by an opponent — a move that's been banned by organized leagues for more than 20 years.
"But still 10 per cent of the kids with brain injuries — and this amounts across Canada to several thousand kids a year — are still getting their brain injury because someone hit them from behind," he said. "So they've been body-checked from behind either into the boards or into another player and sustained a brain injury."
Cusimano said hockey leagues at all levels need to make penalties for such infractions harsher and more strictly enforced as a means of preventing brain trauma in young players, which can potentially have life-long cognitive and psychosocial consequences.
The study, published Thursday in the journal PLoS ONE, categorized injuries by players' ages, what sport they occurred in — both informal and organized activities — and the mechanisms that caused them.
Soccer was second on the list, accounting for 19 per cent of those with a sports-related brain injury. Most of those injured were aged between 10 and 19, with the most common reason being struck by another player, a kick to the head, or a head-on-head collision.
Among players ages five to nine, brain injuries occurred most often from striking a surface or slamming into a goal post.
"There's a really straightforward solution here," said Cusimano. "Padding the goal posts could have potentially prevented a large number of these brain injuries in young children."
Football and rugby were behind 13 per cent and 5.6 per cent, respectively, of the brain injuries sustained by young people who sought treatment at a hospital ER. Being struck by another player, usually in a tackle, was the most likely cause.
Basketball also led to brain injury victims, most of them hurt from being elbowed on the court, especially as kids got older.
"It's getting more common across more sports," Cusimano said of player contact causing injury. "Kids are getting more competitive and therefore more aggressive as they get into the higher age groups.
"As well, their weight and speed is increasing. These are prime physical factors that are going to predict brain injuries as well — the speed of the collision and the momentum that somebody hits another player with."
Baseball, too, ran up its score of harms, accounting for 6.5 per cent of sports-related brain injuries. Young kids were at the highest risk for getting seriously hurt, mostly by contact with a ball or bat.
"We could do a lot of prevention with the young kids, because they're primarily getting hit by the bat and the ball," often because they're standing too close to the batter, said Cusimano.
"So this says a lot for parents in supervision of children, not to just give a five- or six- or seven-year-old kid a bat to go play in the backyard. They've got to be properly supervised and properly taught not to stand too close to the batter."
Helmets also should be used by young children, no matter whether they're on an organized team or playing in the school yard or in a park, he said.
"I think we can instill the idea at a very young age that it's important to protect your brain."
Alison Macpherson, an assistant professor of kinesiology and health sciences at York University in Toronto, said knowing where and how children are getting hurt when they play sports is important.
"And I think that's important first because we really, really want to keep kids in sports," she said Thursday.
Macpherson, a researcher in childhood injuries who was not involved in this study, said children shouldn't play sports only in organized leagues, but also should be free to play informally, with parents supervising some of those activities to help prevent injuries.
"Parents should not take studies like this as a cue to withdraw their children from sports. It's important to be active," she said.
"The take-home message is not 'Don't play these sports.' The take-home message is 'Play these sports in the safest way possible.'"