Around the country, little girls are donning leotards and tumbling into gymnastics classes — a surge of interest that typically happens every four years after the summer Olympics.
But as their daughters dream of becoming the next Shawn Johnson or Nastia Liukin, parents have new worries. Accusations that two members of the Chinese women’s gymnastic team were too young to compete have renewed focus on the Olympic rule that bars gymnasts under 16, an age limit that seeks to protect young athletes from health risks like the incessant pounding that can take a toll on a developing body.
Such worries are hardly limited to gymnastics. While pediatricians encourage children to exercise more, there is growing concern about specializing in just one sport, whether baseball, soccer or ice skating.
Growing bones can’t handle the same stresses as mature bones. When a child specializes in one sport early in life, certain body parts — the arm of a Little League pitcher, the spine of a gymnast — are subjected to repetitive stress and overuse. Especially among young soccer players, there has been an alarming rise in injuries to the anterior cruciate ligament, the main ligament that stabilizes the knee joint — a particular concern because repair involves drilling into a growth plate, an area of developing tissue at the end of the leg bone.
Many gymnasts and coaches say the fears about their sport have been overstated. “Very few athletes make it to the top level where they are pounding their body six or seven hours a day,” said Shannon Miller, an Olympic gold medalist who started the sport at age 5 and competed in 1992 at 15 and again in 1996. (The age limit was adopted after the 1996 Olympics.) “Gymnastics is a great sport to get kids involved in because it leads to so many other things, not just the Olympic Games.”
But this spring the medical journal Pediatrics published a troubling study of gymnastics-related injuries treated in hospital emergency rooms over a 16-year period ending in 2005. on average, 26,600 gymnastics-related injuries are treated by emergency room physicians every year, a rate of about 5 injuries per 1,000 participants. While only 3 percent of the patients were admitted to the hospital, many of the injuries were still serious: nearly half were strains or sprains and nearly a third were fractures or dislocations. Most were to the shoulders, arms and wrists, but a frightening 13 percent involved the head and neck.
The researchers, from Ohio State University, concluded that gymnastics had one of the highest injury rates of all girls’ sports. Lara McKenzie, the study’s lead author and a principal investigator for the Center for Injury Research and Policy at Nationwide Children’s Hospital in Columbus, said that the study shouldn’t discourage parents from enrolling children in gymnastics, but added that they should be diligent about finding a reputable gymnastics program that emphasizes safety. Children should be discouraged from practicing while unsupervised.
“We don’t want them to give up the sport,” Dr. McKenzie said. “Some of these injuries are occurring when kids are doing gymnastics at home or unsupervised. We know when they do it at home they don’t have the same type of training mats or spotting that they would have in a more traditional setting.”
Steve Penny, president of USA Gymnastics, the sport’s governing body, says the study doesn’t accurately reflect gymnastics in an organized setting because it counts things like injuries on school playgrounds and mishaps during a backyard cartwheel. “I think most people view gymnastics as a very healthy thing for young girls,” he said.
At gymnastics centers, business is booming in the wake of the Olympics. At the California Sports Center in San Jose, enrollment jumped 33 percent in August. The owner, Dave Peterson, said parents should look for programs that help children develop skills that will enable them to compete all the way up to college if they choose.
Once children reach a skill level that allows for competition, he said, they train just two hours for three days a week. Over time, the program increases to about 21 hours a week. He added that the coach-to-athlete ratio should be about 6 to 1 in preschool and about 8 to 1 for older athletes.
In the absence of firm data about the best age to start competitive sports, the solution may not be to discourage young athletes from working out too much, but instead to encourage them to try out more sports. The journal Pediatrics reported last year that young athletes who participated in a variety of sports had fewer injuries and continued longer than those who specialized before puberty.
For young athletes determined to specialize, doctors recommend breaks from training at least one to two days a week, and long breaks every two to three months to allow the athlete to do another activity or at least cross-train to exercise different muscle groups.
Ms. Miller, the gymnast, says her sport can give children coordination, flexibility and strength that will help them in other sports. And she adds that the focus shouldn’t be on competition.
“The biggest factor is how excited they are to be there,” she said. “Are they enjoying it and having fun?”
E-mail: well@nytimes.com.