TORONTO - Traumatic brain and spinal injuries appear to be on the increase on ski hills around the globe, say a team of Canadian injury researchers who suggest the rising popularity of acrobatics and high speed on the slopes could be responsible.

Encouraging or requiring skiers and snowboarders to wear helmets would help reverse the trend, they said in an article published Tuesday in the British journal Injury Prevention.

"We feel that every skier and snowboarder of every age, of every skill level should be wearing a helmet,'' said senior author Dr. Charles Tator, a neurosurgeon at Toronto's University Health Network and the founder of ThinkFirst Canada, a charity devoted to prevention of traumatic brain and spinal cord injuries.

"We really strongly recommend helmets. There's very good evidence that helmets provide protection.''

Tator and his co-authors did not conduct original research but instead did a systematic review of the scientific literature looking for studies linking these types of injuries with skiing and snowboarding. They found 24 medical articles from 10 different countries covering the period from January 1990 to December 2004.

A number showed evidence of rising numbers of serious injuries on the slopes. One U.S. study, for instance, showed an increasing trend in skiing-related deaths over a 21-year period.

Another reported that the incidence of spinal cord injuries in children in the study area rose by 130 per cent between 1972-73 and 1993-94; in adolescents, the rate rose by 407 per cent.

To be sure, the numbers of such injuries are low. One study estimated that for every one million visits to a ski hill, between 0.5 and 1.96 people would die. But when traumatic head or spinal cord injuries occur, the consequences can be severe.

"They cause death and lifelong disability,'' Tator said.

Alison Macpherson, an injury prevention expert at York University in Toronto, said what is happening on the slopes runs counter to what is happening elsewhere.

"I was surprised that the incidence of head injury and spinal cord injury is going up because in most other areas the rates are going down,'' Macpherson said. "Injury rates in general seem to be going down.''

The studies showed that snowboarders were substantially more likely than skiers to suffer serious injuries. Males and skiers or snowboarders under age 35 were more likely to be injured, the review showed.

"In our view, there is too much risk being taken on the hills. We don't want to discourage people from participating in these activities. These are great activities. But we want them to participate more carefully,'' Tator said.

"Aerial activity on a recreational mountain and `getting air' on a slope that is populated by people of a wide variety of skiing skills should be avoided.''

The authors call for increased wearing of helmets -- advice echoed by others in the field of injury prevention.

Macpherson noted that many snow parks, the cordoned off areas where snowboarders and aerialists perfect their tricks, require participants to wear helmets. "So it's not that much of a stretch to require helmets everywhere,'' she suggested, noting she and her entire family wear helmets when they ski.

But the president and CEO of Canada West Ski Areas Association, which represents 99 ski hill operators in Western Canada, said his members wouldn't be comfortable with mandatory helmet rules.

"We're not strong advocates of that. We're strong, strong believers in behaving in a responsible manner (on the hills),'' Jimmie Spencer said from Vernon, B.C.

"We tell everybody to consider the use of a helmet. But we would hate to see it become a regulation. . . . You should have a bit of a personal choice in the things you do.''

Shelina Babul, associate director of the B.C. Injury Research and Prevention Unit, said wearing helmets makes sense -- but she noted adults are going to have to model this behaviour for younger skiers if it is going to become accepted.

"I'll go up to a ski hill and I'll see the kids taking the lessons. And they'll be all wearing helmets,'' she said.

"But the instructor won't be wearing a helmet. So what's stopping that child from saying: `Well, why do I need to wear it if my instructor's not wearing it?'''