Risk of injury comes with the thrill of sledding, and using inner tubes and snow disks. Sledding attracts people because it's fun, but also because the equipment cost is low and special training isn't required.

Sledders and onlookers get hurt. The U.S. Consumer Product Safety Commission estimates about 32,000 of the injured visit hospital emergency departments yearly. More than 4 percent of the injuries result in actual hospitalization.A Massachusetts study looked at 211 sled- and toboggan-related injuries of children and adolescents age 19 years or younger requiring emergency department treatment for a 3-year time period. They found that a single type of injury unique to sledding does not exist, and that injuries can occur with any type of sled. Twenty-nine percent of all injuries studied were lacerations; 26 percent, bruises; and 19 percent, sprains or strains. Twenty-one percent were serious injuries, which included concussions, internal injuries and fractures.

The Physician and Sportsmedicine journal cited several behaviors that put sledders at risk for an injury. For example, sledding down a hill in a prone position enhances the likelihood of head injuries if a sledder collides with trees or other objects.

During the evening, obstacles become more difficult to spot. People in their teens are likely to participate in the activity at night, after school or work - when it's dark. Falling out of a sled can produce a neck injury. A sudden stop forward can cause a cervical strain, similar to whiplash.

Inner tubes and snow disks may be more dangerous than sleds because of the lack of steering mechanisms. One Denver physician believes that a "tuber" is 25 times more likely to be injured than a skier. Any safe sitting position is difficult to find on tubes. The main injuries are obstacles such as trees, people, dogs, fences, cars and large bumps.

Connecting tube chains is another dangerous practice. This occurs when a group of tubers forms a line and places their legs under the arms of the person in front of them, making a tightly packed "chain." Though such a chain is exciting, tubers can quickly get into trouble.

Sledders should dress appropriately by dressing in layers. Wool repels moisture and retains body heat better than many other fabrics. If possible, wear a shirt and leggings made of polypropylene beneath cotton to shunt water away from the body, a water-repellent jacket, gloves or mittens, and a hat with earmuffs or a wood stocking cap. Wearing helmets can reduce the risk of head injuries during falls or collisions.

The sledding area should be free of obvious hazards, such as large rocks, debris and trees. The area should be far from automobile traffic. Slopes of less than 30 degrees should be used. A flat runoff at the bottom of the slope is necessary for the sled to slow down. Try to avoid areas that are crowded with people. The more people on a slope, the more likely sledders are to collide with other sleds and other people.

The American Academy of Pediatrics suggests that children should not be allowed to play outside when the windchill factor is -20 degrees or colder.

Though sleds, tubes and snow disks can plow through winter blahs, they also can be hazardous devices to unknowing, unprepared sledders and tubers.

- Alton Thygerson is a professor of health sciences at Brigham Young University.