Playing too hard? As young athletes train nonstop, doctors are seeing a big rise in injuries.

Jeret Adair, a top young pitching prospect from Atlanta who started 64 games in one summer for his baseball team, last year underwent an elbow reconstruction that was once reserved for aging major leaguers.

'YOU PLAY WITH PAIN'

"My arm hurt for years, but I never went to the doctor," says Adair, 16, a junior at Riverwood High School. "Like they say, you play with pain. If you're a good pitcher on a team of 14- or 15-year-olds, you're going to be throwing too much. Everybody wants to throw their ace out there."

When Ana Sani of Scarsdale, N.Y, was a 13-year-old budding soccer star, she practiced daily until she tore a ligament in her left knee. After a 10-month rehabilitation, she returned to playing soccer--on three teams at the same time. Now 18, Sani has finished her first season on the soccer team at Williams College in Massachusetts. She recently tore cartilage in the same knee.

Around the country, doctors in pediatric sports medicine say it is as if they have happened upon a new childhood disease, and the cause is the overaggressive culture of organized youth sports.

"They are overuse injuries pure and simple," says Dr. James Andrews, a prominent sports orthopedist who performed the elbow surgery on Adair. "You get a kid on the operating table and you say to yourself, 'It's impossible for a 13-year-old to have this kind of wear and tear.' We've got an epidemic going on."

EARLY SPECIALIZATION

Typical injuries range from stress fractures, growth-plate disorders, cracked kneecaps, and frayed heel tendons, to a back condition brought on by excessive flexing that causes one vertebra to slip forward over another. Most are injuries once seen only in adults.

One factor has been repeatedly cited as the prime cause for overuse injuries among young athletes: specialization in one sport at an early age and the year-round, almost manic, training for it that often follows.

"It's not enough that they play on a school team, two travel teams, and go to four camps for their sport in the summer," says Dr. Eric Small, who has a family sports-medicine practice in Westchester County, N.Y. "They have private instructors for that one sport that they see twice a week. Then their parents get them out to practice in the backyard at night."

Dr. Angela Smith of the Children's Hospital of Philadelphia says parents are pushing their children to excess in pursuit of college scholarships or the dream of a professional sports career. "The volume of training has increased beyond the maturing young body's ability to handle it," she says.

Doctors lament the loss of what has become a cultural artifact: the playground athlete. Two decades ago, "Children might have played baseball, basketball, and football all in the same day," says Dr. Lyle Mitchell of Boston Children's Hospital. "This was good for their bodies, which developed in balance. Now, young athletes play sports supervised by adults who have them doing the same techniques, the same drills, over and over and over."

IRREVOCABLE DAMAGE

It is not uncommon for the damage done by an overuse injury to be irrevocable, and the doctor's advice is to quit the sport. "To tell you the truth, the kids usually take it better than the parents," says Dr. Michael Busch, an orthopedic surgeon in Atlanta. "Many kids are relieved. They can be kids again."

The doctors who treat young athletes say participation in sports should be encouraged--that sports are vital to the health of America's children--but that athletes should take certain precautions.

One approach to limiting overuse injuries involves training that is specially designed to prevent injuries. Of special focus is teaching young athletes how to decelerate correctly because many injuries result from a sudden stop or change of direction.

Experts also advocate stopping year-round play in one sport, so that overused parts of the body have a chance to rest and recover.

'TAKE A REST'

"At least three months off," says Andrews. And for baseball and softball pitchers, he would also ban the radar gun, which measures the speed of a pitch. "That thing has wrecked more arms," he says. "I'm sick of seeing these kids being torn apart."

While Adair is still recovering from his elbow surgery, he is tossing a baseball again and is hopeful about returning to pitching--with a strictly enforced pitch count--by this summer.

"I'm the living example of someone who did too much," says Adair. "I would tell young kids coming up now: 'Don't be such a hero. Take a rest.'"

Bill Pennington is a sports reporter for The Times; additional reporting by Bruce Weber.