Sometimes she’d run 50 miles a week.

At first the extra miles paid off, and Elaine cut several minutes off her 5K cross country time. Then, during a race, a bone in her foot broke. Now, she can’t run at all.

Such is the plight of a growing number of athletes, both male and female, who train their young bodies past the point of diminishing returns and right into injuries.

The American Academy of Pediatrics estimates that more than 30 million children and teens participate in organized sports each year. Of those, about 3.5 million seek treatment for overuse injuries and chronic fatigue from overtraining. Though no data exist, local sports medicine specialists say they’ve seen a steady increase in the number of injured and over-trained athletes between ages 8 and 18 by as much as 25 percent in recent years.

Experts attribute that increase to more and more children specializing in only one sport and playing it year-round for school, select and traveling teams. That leaves no down time for rest and repair.

Sometimes, experts point out, it’s because parents and coaches put pressure on children to excel. But kids often put the pressure on themselves. Elaine, a sophomore at Gateway Academy in Chesterfield, created her own high-mileage program to supplement workouts with her track and cross-country teams at school.

"I really have a fixation on doing the best I possibly can, whether it’s (academically), running or cheerleading. And this is one of those things I felt like I could do better," Elaine said.

A couple of years ago, Claire Dreyer, 15, quit playing several sports to focus on tennis. Soon, she was on-court 14 to 15 hours a week.

Six weeks ago, her athletic career also came to a screeching halt when she suffered a torn tendon in her left foot in a match. Claire, a sophomore at Webster Groves (Mo.) High School, said her two older brothers were always ultra-competitive, which rubbed off on her.

Steve Stahle, primary care sports medicine physician at U.S. Center for Sports Medicine in Kirkwood, Mo., said that kids are also susceptible to growth plate injuries. The growth plate is the area of growing tissue near the end of long bones in children and adolescents. The femur in the thigh and the humerus in the upper arm are two examples and each one has a growth plate at both ends of the bone. Those plates determine the future length and shape of the mature bone.

"You can strengthen your muscles, but you can’t strengthen your growth plate," Stahle said. An overdeveloped muscle will pull on the slower growing, soft-tissue plates, increasing the risk of injury.

"Kids think they need to be training every day, when it’s often better for them to take a few days off," Stahle said. "But it’s hard to convince them of that and sometimes their parents, too."

He often tells them they might have the best 12-year-old pitcher in the history of Missouri but that if he injures that growth plate, his arm will stay 12 years old, while everyone else’s is advancing.

"Kids are constantly told, ‘Work hard and you’ll get recognized. You play more, you get more exposure,’" Stahle said. "And they know they have to train hard to make it to the elite level. So a lot of times their parents don’t even have to tell them that."

Dr. Mark Halstead is a pediatric sports medicine specialist with St. Louis Children’s Hospital and Washington University. He attributes the increase in overuse injuries and overtraining, which is a condition of chronic fatigue, to the explosion in the number of select and travel teams as well as performance enhancement training.

"When I participated in high school sports 20 years ago, the sports environment was nothing like it is now, especially with girls, who often have an even more intense drive than boys," Halstead said.

Scott Roberts, director of performance training at the Sports Medicine and Training Center in Webster Groves, agrees. He sees athletes come to the center who play soccer or volleyball for school and select teams, with one season practically running into the next.

"You’re talking about a total of six weeks off all year long," he said. "It’s unbelievably intense and the time demands are staggering."

But many young athletes and their parents feel the select teams are necessary because they’re a higher level of competition that offers the most exposure to college recruiters, he said.

"I think recruiting has shifted. In the early ’90s there was still an emphasis on high school sports, and recruiters would go to those games. Now they can go to a showcase tournament for soccer or volleyball select teams and see the best of the best."

Elaine Gill spent five weeks hobbling around on crutches with a boot and then a cast. And while she’s back in tennis shoes, Elaine is still unable to run or do cheerleading.

But she’s well on her way to a full recovery and said she’s learned an important lesson: "Absolutely," she said. "Not to over-train. The consequences far outweigh the benefits."