June 22 (HealthDay News) -- Many snowboarders and skiers who pursue their pastime off the main slopes are going slow enough so that a helmet would give significant protection from head injuries, a new study finds.

Currently, ski/snowboard helmets offer only limited protection in a direct collision at speeds greater than 15 mph. On open slopes, skiers and snowboarders can reach speeds of 25 mph to 30 mph.

But in this study, U.S. researchers clocked the speeds of expert skiers and snowboarders as they went through non-traditional ski areas such as terrain parks and gladed areas.

They found that the participants' speeds were below 15 mph 87.6 percent of the time.

At these slower speeds -- which result from the variation and change of direction needed to navigate non-traditional ski areas -- helmets would offer significant protection, the researchers concluded.

Each year, about 139,000 skiers and snowboarders suffer injuries that are serious enough to require treatment in an emergency department. While traumatic brain injury is the leading cause of death and serious injury among skiers and snowboarders, rates of helmet use are low, particularly among adults, according to background information in the study.

The findings are published in the latest issue of Wilderness Medicine magazine.