Proper nutrition is crucial for adolescents, as they experience a growth rate second only to infants.
A typical 10-year-old requires a minimum of 2,000 calories a day, while 15- to 18-year-old boys require 3,000 calories a day. Add sports to the mix and you have one hungry teenager, says Gail Allen, P.N.P., a pediatric nurse practitioner in Chester, Virginia.
To be sure your teenage athlete isn't running on empty before practice or a game, Allen offers these reminders:
Parents often tell their kids to "use their heads." When it comes to soccer, that might not be such good advice. A study of 53 Dutch professional soccer players found that "heading" -- hitting the ball with your head -- too many times may impair memory and recognition skills.
And while very few studies have been done on kids, Dr. Lyle Micheli, of the sports medicine department at Children's Hospital in Boston, believes that no one under age 12 should "head" a soccer ball. Before that age, children's muscles aren't fully developed. He compares the impact of a soccer ball to taking a punch in the face in a boxing ring.
To be safe, Dr. Micheli suggests letting some air out of heavier soccer balls for less impact. Or ask the coach about using a size 4 ball. It's lighter than the professional size 5 ball used by most American kids. European kids play with the smallest and lightest ball -- a size 3 -- and don't move up to a size 5 until they're 18.
It's extremely rare, but about two children die each year after being struck in the chest by a baseball. The most susceptible kids are those between 6 and 9 years who weigh under 90 pounds.
Children's ribs are more elastic and less protective than adult ribs. Although it's unclear what exactly causes the heart to stop, doctors think the impact probably disturbs the heart's natural rhythm.
The American College of Sports Medicine, however, says routine use of chest protectors isn't justified based on what's known. But it says catchers at all levels of play should always wear chest protectors, and it encourages more research and experimenting with lighter, softer balls.
Most kids who play on organized football or hockey teams wear mouth guards because they have to, but only 7 percent of the rest of young athletes wear them.
This is troubling considering 15 to 17 percent of all sports injuries happen around the face. Every year, 5 million teeth are knocked out in sports such as basketball, baseball, soccer, volleyball, rollerblading, mountain biking, and the martial arts.
The good news is that mouth guards prevent 200,000 oral injuries each year, says H. Douglas Mougey, D.D.S., a dentist in Scottsdale, Arizona, and spokesman for the Academy of General Dentistry.
Most athletes who buy mouth guards get them from sporting goods stores. These $3 to $25 boil-and-bite guards are less protective against oral injuries and concussions, but are much less expensive than the $150 custom guards made by dentists (which usually are not covered by insurance). Dr. Mougey says the extra money is well worth it.
Custom mouth guards fit better and interfere less with breathing and speech; they're also more comfortable, he says, so young athletes are more likely to wear them. But he admits they're a tough sell to patients -- until one of them loses a tooth.
"People don't think anything of paying $120 for sports shoes that last six months," he says. "But they wonder about paying a little more for a year or two of protecting your mouth. And if there's an injury, it could cost thousands of dollars to repair."
Students who punch and tackle in sports may be doing the same thing on the playground.
Nancy G. Murray of the University of Texas-Houston School of Public Health studied sixth-grade girls and boys for one week. Students who played football, wrestled, lifted weights, or boxed were the students who did the most teasing, name-calling, threatening, and hitting. Students who played volleyball, jumped rope, and biked did fewer aggressive acts during the week.
Murray says, "A sports setting would be a great place to deliver violence-prevention interventions, such as teaching kids to walk away from fights."
Your 11-year-old, the one with the pencil neck and pipe-cleaner arms, comes home one day and announces he's going to play football. To prepare, he wants to start lifting weights. Should you let him?
Until the 1980s, resistance training wasn't recommended for prepubescent and adolescent kids. The thinking was that youngsters couldn't bulk up because their bodies don't produce the hormones needed to increase muscle mass, and they would risk fracturing developing bones.
But research in the past 10 years has shown that children can gain strength from weightlifting without suffering injuries, regardless of age, says Harvey Newton of the National Strength and Conditioning Association.
While it's true muscles don't grow without testosterone, resistance training causes changes in the nerves controlling the muscles, which leads to increased strength. Resistance also strengthens ligaments, tendons, and bones, which helps prevent injuries.
The best place to train is a supervised school site. Weight gyms may be OK, says Newton, but some children are encouraged to lift too much too soon.
Training at home is convenient but not always safe. Adult supervision is a must. Parents can buy a 110-pound weight set (barbell, two dumbbells, and weights) at most sports stores. Expect to pay around $200 for a set that includes a workout bench and squat rack.
Workouts vary by sport and goals. Start with 5 to 10 minutes of warm-up (light jogging followed by stretching), and then select a weight that can be lifted easily. Do two or three sets of eight to 15 repetitions, training two to three nonconsecutive days a week.
Playing high school sports can do many things for young women, and now it may help them get a running start on preventing osteoporosis later in life.
Researchers at Purdue University found that participation in high school sports increased mineral content of hip bones by about 7 percent and of all bones by 5 percent.
Dorothy Teegarden, Ph.D., an assistant professor of foods and nutrition, studied bone mass development resulting from past physical activity levels in 204 minimally active women age 18 to 31. The women in the study had participated in a variety of weight-bearing sports such as cross-country, track, soccer, and basketball.
Not only can exercise build bone density while women are young (females cannot build bone density after 25 or so), but working out may also help slow the decline in density as women age.
"It seems that if you want to maximize your bone density potential, you need to start at an early age," Teegarden says. "If we can have young women reach maximum bone density while they can, then we might be able to prevent osteoporosis later."
One-fourth of all white women will have osteoporosis in their lifetime, Teegarden says. More than 25 million people already have the disease, in which bone breakdown occurs faster than replacement. As a result, bones become weak and fracture easily.