About three million young people in the United States are involved in cheerleading. People often think of cheerleaders when they think of school spirit. Cheerleaders are a tradition at football games and other sports events. They help get the crowds excited for their team.

In the past, cheerleading at American schools mostly involved shouting cheers and jumping up and down. But cheerleading has grown into a sport of its own. The moves are more physical. Cheerleaders, for example, are often thrown into the air.

The difficulty of modern cheerleading has led to more injuries. A new study shows that the number nationwide increased one hundred ten percent during the years examined. It says hospital emergency rooms treated more than two hundred thousand cheerleaders between nineteen-ninety and two thousand two.

During that same period, the number of students who became cheerleaders increased by eighteen percent.

Two children's medical researchers in Ohio did the study. The report appeared this month in the Journal of Pediatrics.

Almost all of the injured cheerleaders were female. Eighty-five percent of the injuries were in those between the ages of twelve and seventeen.

Leg and foot injuries represented the largest share of cases, thirty-seven percent. Nineteen percent were injuries to the head or neck.

But the study says few cheerleaders were injured seriously enough to be admitted to the hospital. Almost ninety-nine percent were treated and released from the emergency department.

Researchers say cheerleaders often attempt difficult performances before they are physically ready. They are often expected to perform risky moves when they compete for honors against other schools.

Most school sports are played during one season. Cheerleading is done all year. So it is difficult to compare the injury rates to other sports.

In many American schools, cheerleading is not considered an official sport. This means it is not held to the same rules and requirements. Because of this, the adult coaches who direct cheerleading programs are often not required to complete any special training.

In their report, the researchers call for steps to increase the safety of cheerleading. These include required safety training for all coaches.