functional body weight training
About 30 million children participate in organized sports in the United States; every year, three million to four million of them get injured. Dr. Metzl points to the rising number of young athletes suffering injuries to the anterior cruciate ligament -- the main ligament that stabilizes the knee joint -- as evidence of the need for greater emphasis on strength training in youth sports. Exercises like squats can strengthen the muscles around the knee joints, making them less vulnerable.
"A number of studies show that strengthening the muscles around the knee reduces the risk of A.C.L. injuries," Dr. Metzl said. "Stronger muscles make you a better athlete, but also a safer athlete."
"We want kids to play sports," he added, "but we also want to figure out how to make them safer."
But exactly what constitutes safe and effective strength training for young people? Dr. Metzl says the most important thing to realize is that strength training is not the same as powerlifting. For youngsters, the emphasis should be on low weight and high repetitions. If a child cannot lift a weight for 15 reps, then it's too heavy, Dr. Metzl says. In fact, many of the most useful strengthening exercises for children are full-body movements that do not involve any weights at all.
Many of these movements are demonstrated in a video that Dr. Metzl and the American Academy of Pediatrics released this month for parents and adolescents, called "Home Strength Training for Young Athletes".
The video looks like any other workout series, except the instructor -- a buff Dr. Metzl, who is preparing for an Ironman race -- leads a group of children ages 8 to 16 through a variety of exercises that can be done at home. The only equipment required is a set of light dumbbells.
Many of the exercises involve functional body weight training -- essentially using your own weight for resistance. Dr. Metzl leads his pint-size workout warriors through exercises like jump squats, biceps curls and overhead "presses" with weights (done while balancing on one foot). Some other movements Dr. Metzl teaches his young athletes are push-ups, single-leg squats and a tough, core-building exercise called mountain climbers, as well as burpees, a series of movements executed in rapid succession that develop agility, coordination and strength.
Doing these exercises at home -- in a roughly 45-minute session two or three times a week -- has several advantages, said Dr. Gregory of Vanderbilt Children's. For one, it allows parents to watch or join in on the workout. Many commercial gyms have a minimum age limit that forbids adolescents, and most children would risk injury trying to use machines designed for adults anyway.