Adults recall childhood as an endless blur of running and jumping, full of little cuts and bruises, but blissfully free of those nagging injuries that follow exercise later in life -- tendinitis, bursitis and stress fractures.
Now, however, orthopedists and pediatricians say these injuries are cropping up with alarming frequency in children: from stress fractures of the lower spine in young gymnasts to shoulder tendinitis in swimmers to shin splints in aspiring marathoners.
"People are suddenly recognizing that it's a problem," said Dr. Carl L. Stanitski, chief of orthopedic surgery at the Children's Hospital of Michigan in Detroit. "We are seeing more and more stress fractures in children and more and more injuries cause by repetitive use."
They attribute the rise in such so-called overuse injuries to intensive sports training programs for young children, longer playing seasons and specialty sports camps in which children may spend hours lobbing balls on a tennis court or throwing hundreds of pitches each day.
In addition, doctors say they are now identifying injuries that in the past might have been ignored.
"In my practice, overuse injuries are much more common than acute injuries, like lacerations and broken bones," said Dr. Gregory L. Landry, a staff pediatrician at the University of Wisconsin Sports Medicine Clinic. "Part of that may be we're getting better at diagnosing these things in kids. In the past, pediatricians did not expect these syndromes in children, so they overlooked the diagnosis or called them growing pains."
Although overuse injuries generally respond well to rest, if ignored they can cause major problems.
". . . If kids are caught in an environment where there is pressure to throw through the pain or tough it out, these injuries tend to progress to chronic injury, sometimes lifelong disability, which is really a crime," said Dr. Barry Goldberg, director of Sports Medicine at Yale University Health Services.
Experts say children are particularly prone to injury from intensive sports. The quality of their equipment and coaching is often not on par with the athletic demands. And children's immature bones have soft areas that are common sites of injury.
"The most ill-equipped athlete in America is a third-string middle-school football player, who's running his heart out on an adult-size field, wearing a hand-me-down helmet and shoulder pads," Dr. Stanitski said. To prevent overuse injuries, he and others have advocated that young children should play on smaller fields, using smaller, lighter balls that are proportioned to their size.
Dr. Landry said that at the start of the school soccer season each fall he sees an epidemic of heel pain caused by tendinitis. He said poorly designed shoes were partly to blame.
"Soccer shoes for children have not caught up with the rest of the sports shoe industry," said Dr. David Bernhardt, a sports medicine fellow at the University of Wisconsin. "They don't provide enough support."
All too often children's coaches, who are often volunteers and rarely have formal training, drill children the way "some troglodyte coached them in high school or college," Dr. Stanitski said. They also do not teach proper techniques, which puts excess stresses on young bodies.
"In Little League, the coach takes the biggest, strongest kid and says, 'You're the pitcher,' " Dr. Stanitski said. "And he throws with his arm, not using his leg or his body as real pitchers do. Until someone shows that kid how to pitch, he's a setup for overuse problems."
Young baseball players may suffer from tendinitis of the shoulder and elbow, he said, as well as bursitis, an inflammation of a fluid-filled cushion in the shoulder.
Some overuse injuries in pre-adolescents are peculiar to children, occurring at the attachment of tendon to bone, a particularly weak junction in the young. Before puberty, the bone beneath these sites is soft, more like a gristle, and vulnerable to microscopic fractures and inflammation.
The heel pain that afflicts children in running sports like soccer, called Sever's disease, is caused by irritation where the Achilles' tendon from the calf attaches to a bone in the foot.
In children, overuse injuries occur most often at the start of the season, when bodies are out of shape, or at its peak, when they are bearing the maximum forces they can tolerate.
Regular exercise causes microscopic trauma to tissue, which generally heals during the hours or days of rest in between. As long as the body is given adequate time to repair itself, the person builds up muscle and becomes better conditioned.
But when a child exceeds the body's ability to heal the damage, doing too much, too fast, the tissue starts to break down and overuse injury occurs.