While cheerleading injury rates are lower than for many other high school sports, the accidents that do happen may be more severe and more likely to result in concussions, a U.S. study suggests.

On average, cheerleading typically has less than one injury for every 1,000 minutes of participation time, meaning there's no more than one accident every 17 hours, the study found.

That's far less dangerous than most other high school sports - only track and field and swimming are safer. Injury rates are more than four times higher for football, for example, and three times higher for girls' soccer.

"We believe cheerleading had a lower rate of injury than most sports because there is less athlete-athlete contact in cheerleading than the collision sports like football and lacrosse or even sports like soccer and basketball," said lead study author Dustin Currie, a public health researcher at the University of Colorado Anschutz Medical Campus.

Concussions were the most common injury for cheerleaders, accounting for about 31 percent of cases, the study found. Even so, concussion rates were significantly lower in cheerleading than in all other sports combined, and all other girls' sports.

"Although injury rates are low, when injuries do occur in cheerleading they tend to be more severe than when injuries occur in other sports (i.e. they tend to be concussions, fractures, etc.)," Currie added by email. "That may be because cheerleaders, due to the nature of the sport, are more likely to have falls from elevation - for example, flyers during stunts - or to land awkwardly or be struck by another athlete landing awkwardly - for example, bases during stunts."

More than half of all accidents happened during stunts, the researchers reported in Pediatrics.

Although almost all of the injuries happened to girls, the injury rate was 33 percent higher for male cheerleaders than for females. That may be because boys are more often at the base of pyramids and other formations used in aerial stunts and are also more likely to participate in flying stunts, Currie said.

To assess cheerleading injury rates, Currie and colleagues analyzed data from a national registry of high school sports injuries from 2009 through 2014.

Over the study period, there were 1.1 million athletic exposures (AEs), or competitions or practices with a potential for injuries, and 793 cheerleading injuries.

That amounts to an overall cheerleading injury rate of 0.71 per 1,000 AEs, 63 percent lower than all other high school sports combined and 51 percent lower than all other girls' sports.

The most commonly injured body sites were the head and face, ankles, hand and wrist, or trunk. After concussions, the most common type of injuries were ligament sprains, muscle strains and fractures.

For about one third of cheerleading injuries, athletes resumed participation in less than one week, while about 41 percent of cases kept them sidelined for one to three weeks. Another 11 percent of injuries required cheerleaders to sit out for a more than 3 weeks and 5 percent resulted in medical disqualification for the entire season or ended the athlete's career.

One limitation of the study is the reliance on school athletic trainers to report injuries to the national registry, which excludes data from schools that don't have these trainers on staff, the authors concede. The study also lacked data to compare injury rates between elite squads and cheerleaders who don't regularly participate in competitions.

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Injuries may be more likely when cheerleaders are practicing new maneuvers for competitions, such as stunts, throws and pyramid routines, said Larry Cooper, chair of the secondary school committee for the National Athletic Trainers' Association and head athletic trainer at Penn Trafford High School in Harrison City, Pennsylvania.

"It's important that cheerleaders have good instruction on individual stunts; that mats are at all practices, competitions and performances; and doctors and athletic trainers are on the sidelines to monitor incidence of concussion and to provide appropriate care should an injury occur," Cooper, who wasn't involved in the study, said by email.