When it comes to exercise, American youngsters often fall into two extremes: overweight "tater tots" who watch up to five hours of TV a day and overbooked athletes who engage in an excessive amount of sports activities.

The result, sports medicine experts say, is an alarming increase in both the number and severity of youth sports injuries.

"Kids today don't walk and bike and participate in the kind of free play that keeps them in shape," notes Letha Griffin, orthopedist for Georgia State University's varsity athletic teams. For a variety of societal reasons, she says, many children now get most of their exercise in organized sports.

When out-of-condition kids play a sport, they're at increased risk of getting hurt. On the other end of the spectrum, highly conditioned young athletes are vulnerable to overuse injuries from performing repetitive movements to excess.

"Youngsters also are especially susceptible to injury because their muscles, bones and ligaments are still growing," says Griffin, who is a spokeswoman for the American Academy of Orthopaedic Surgeons (AAOS). This summer, the academy launched a national public education campaign, "Play It Safe," to teach parents and children fundamentals of sports injury prevention.

Up to half of all youth injuries in organized sports could be prevented, says the American College of Sports Medicine (ACSM). In its statement on "the prevention of sports injuries in children and adolescents," the ACSM says injury risk could be reduced through the use of pre-activity exams, proper safety equipment and appropriate physical and psychological training.

Researchers at Duke University in Durham, N.C., have uncovered an association between fatigue and injury in youth soccer, the country's fastest-growing team sport. In 1997, they launched a study to catalog injuries suffered by more than 6,000 Raleigh-Durham area soccer players ages 11 to 18, 67 percent of whom are male.

Just-released findings from the first year of data collection show that 90 percent of injuries happened during games, not practice. "Most injuries occurred at the end of the first and second halves of games," says associate investigator Marco Rizzo, an orthopedic surgery resident and former college soccer player. "The speculation is that kids play harder during games than practice, and that they tend to lose form and get sloppy when they're tired, which can lead to injury. That's why there's no substitute for good athletic training, so kids are in condition to play their sport."

Most injuries were minor, with 87 percent of hurt players missing fewer than seven days in a season for each injury. Defending players were more likely to be injured than offensive players, and the rate of injury increased with age. "This may occur," Rizzo says, "because the older the players, the bigger the impact when they collide."

Ankle sprains were the most common injury, and more than 80 percent of all ankle injuries involved previously injured ankles. "We know that once you injure ligaments, they're never going to return 100 percent," he notes. "That's why it's advisable to use protection--such as a brace, Ace wrap or tape--to support that ankle. Yet 90 percent of these injuries occurred in people not using any support."

Proper safety equipment also is essential to prevent sports injury, says orthopedic surgeon David H. Janda, who directs the Institute for Preventative Sports Medicine (IPSM) in Ann Arbor, Mich. His studies have shown that padded goal posts can reduce the risk of serious injury to soccer players and that shinguards--particularly those with bubble-like air systems--can reduce the risk of minor injuries.

Proper training techniques are also crucial, Janda says. As an example, he points to soccer drills involving the practice of "heading" the ball. When improperly done, he says, "heading drills can leave kids staggering around the field like punch-drunk" boxers. To teach the technique safely, he advises coaches to use lightweight beach balls and to instruct youngsters to stabilize their heads by tucking their chins and hitting the ball at the hairline, slightly above the forehead, the spot where the skull is thickest.

One of the best ways to prevent youth sports injury, Janda says, is to "make sure your child is being taught by a knowledgeable individual who understands training and conditioning principles that are age-appropriate."

Resources

* "Play It Safe," a brochure from the American Academy of Orthopaedic Surgeons, is available free by calling 1-800-824-2663 or visiting the academy's Web site, www.aaos.org.

* The Institute for Preventative Sports Medicine offers information by writing P.O. Box 7032, Ann Arbor, MI 48107, or visiting the Web site www.ipsm.org.

* The American College of Sports Medicine offers a copy of its guidelines. To get one, send a self-addressed, stamped envelope to Youth Sports Injuries, ACSM, P.O. Box 1440, Indianapolis, IN 46206. You can also visit the college's Web site, www.acsm.org.

What Parents Can Do to Prepare Young Athletes

As parents, you can do a lot to help young athletes get ready to play sports. Experts advise that you make sure your children:

* Get to practice early enough to warm up and stretch. "There's an assumption that all kids are flexible," says Letha Griffin, team orthopedist for Georgia State University, "but this is not necessarily true--especially during times of rapid growth."

* Are well-hydrated and fueled. Offer a pre-practice snack such as a banana or peanut butter on a bagel, and fill a drink bottle with watered juice or a sports beverage.

* Wear proper apparel and protective gear. This includes batting helmets with face guards for baseball, helmets for bicycling and helmets, knee pads, elbow pads and wrist guards for in-line skating. It also includes sport-specific footwear that is laced and tied.

* Have a pre-participation medical exam. For competitive athletes age 13 and up, this should include a cardiovascular screening.

* Focus on fun. "Some injuries are sustained because kids are working so hard to please Mom and Dad," says David H. Janda of the Institute for Preventative Sports Medicine. "Sometimes the best thing a parent can do is ease up."