Parents who reach for a ski helmet when their children are going tobogganing may not be making the safest choice, a new study shows.

The study from the University of Ottawa and the Children's Hospital of Eastern Ontario shows that hockey helmets performed better than ski helmets in most instances of crashes - and even bicycle helmets performed better at high velocities.

"Alpine helmets had limited effectiveness at both the low and high velocity impacts," the study concluded.

But any helmet is better than no helmet - and yet only about five per cent of kids who go tobogganing wear one, says the study published in the Journal of Neurosurgery: Pediatrics.

Doctors who led the study said the results point to a real need for the development of a new multi-impact helmet for winter sports - and the need for some improvements to ski helmets in general.

"I think ski helmets could do better," said Blaine Hoshizaki, director of the Neurotrauma Impact Laboratory at the University of Ottawa. "There's no reason they couldn't be a little thicker. Even one-eighth of an inch would be better."

Hoshizaki and Michael Vassilyadi from the CHEO tested three types of helmets that children age seven and under might wear to go tobogganing: ski, hockey and bicycle helmets.

They were impacted at two, four, six and eight metres per second at the front and side to simulate the kind of impact a child might experience while sledding.

While the hockey helmet did best at every speed except eight, Hoshizaki said a ski helmet should have done better, particularly at six. "This really showed that alpine helmets could be more protective," said Hoshizaki.

"I was taken aback by the performance of the alpine helmet," said Vassilyadi.

But he cautioned parents who might think a bicycle helmet is great for tobogganing: Once you put even a thin hat under it, the helmet becomes almost useless because the fit is compromised.

Last week, a study from Université de Montréal showed that concussions are a regular occurrence in winter sports and parents are making a mistake if they believe their children are resilient enough to "play through" a head injury.

The study found that concussions in children were as serious and long-lasting as those in adults - and those suffered by adolescents had the most serious consequences of all.

Debbie Friedman, director of the Montreal Children's Hospital Trauma Centre, said children should be wearing helmets for all winter sports. Every year, the centre sees about 200 injuries from skating, 150 from snowboarding, 140 from skiing and 120 from tobogganing. About half are concussions, she said.

Ottawa-based Impakt Protective has developed Shockbox helmet impact sensors that can alert a coach (or parent) to the severity of a blow on the ice so a player can be pulled if necessary.

"Concussion symptoms often appear after the impact so this lets a coach know how hard a player has been hit," said CEO Danny Crossman.

He developed the device for the British and U.S. armies to measure blast acceleration. With a focus now on hockey and football, said Crossman, he's just moved from one war zone to another.

kseidman@ montrealgazette.com