Is Weight Training Safe for Kids?

Experts say weight training is safe for healthy children -- with some precautions.

Medically Reviewed by Louise Chang, MD on February 03, 2010
4 min read

Is strength training safe for children and teens? Will it help them stay fit, compete in sports -- or will it hamper their growth and pose an injury risk?

Fitness and children's health experts answer those questions and more.

According to the American Academy of Pediatrics (AAP), strength training -- which includes lifting free weights, using weight machines, or doing exercises that use elastic tubing or one's own body weight for resistance -- can be safe, if these rules are followed:

  • Wait until the child is old enough.
  • Get a check-up first.
  • Don't overdo it.
  • Make sure the child's workouts are supervised by a qualified trainer who emphasizes safety and correct technique.

Weight training improves strength in teens and preteens. "Not the way an adult male would increase muscle size -- they won't get bulky and big like an adult, but will have increased strength," says Teri M. McCambridge, MD, a pediatric sports medicine specialist in Towson, Md. who chairs the AAP's council on sports medicine and fitness.

McCambridge and colleagues wrote the AAP's 2008 policy statement on strength training in children and teens. That project involved reviewing recent research on the topic.

At least 7 or 8, McCambridge says. It takes that long for the child's balance and posture control to mature, according to the AAP.

The child's age also affects how much weight they should use. ''The younger they are, we recommend light weights, proper form, higher repetitions," McCambridge says.

But children 7 to 8 probably don't ''need'' to strength train to have a well-rounded physical activity regimen, McCambridge says.

Weight training programs must be appropriate for the age and development of the child. Supervision is crucial, especially with younger children.

Free weights may be better than machines, which are typically designed for longer limbs, says Debi Pillarella, a certified personal trainer and fitness program manager for the Community Hospital Fitness Pointe in Munster, Ind., and American Council on Exercise spokeswoman. That may change, she says, as "some companies are making youth-sized equipment."

Not if it's done in a safe, supervised, appropriate manner, according to the AAP. Fears about weight training affecting growth are unfounded, Pillarella says.

Body building and competitive weight lifting is another matter. In its 2008 statement on strength training for children and teens, the AAP says it is "hesitant" to support competitive weight lifting in children whose skeletons are still maturing. The AAP also says it is "opposed to childhood involvement in power lifting, body building, or the use of one-repetition maximum lift as a way to determine gains strength."

The data on whether strength training improves children's sports performance is inconsistent, McCambridge says.

Pillarella's 13-year-old son, Joe, says weight training several times per week at home or at a gym has helped him as an athlete. "In baseball, it made my swing stronger," he tells WebMD.

Some research suggests that "prehabilitation" -- strength training that targets body areas often hit by overuse injuries -- may reduce injuries in teens. But it's unclear if the same benefit applies to preteen athletes.

There is no evidence that strength training can reduce ''catastrophic" youth sports injuries -- the kind that could bench a young player for a season or longer, according to the AAP.

Pillarella says she's seen weight training improving children's posture, body composition, and self-image.

In the teen program she directs, the kids are asked when they come in, "On a scale of 1 to 10, how do you feel about your body?" Over time, with weight training, the scores improve. "We can see over time, their self-esteem numbers will go up," Pillarella says.

Yes, if their doctor approves. "In obese kids, it's actually a good activity," McCambridge says. It can improve their cholesterol levels, build strength, and perhaps help them lose weight.

And, for teens and pre-teen who aren't into sports, weight training may evolve into a lifelong exercise, McCambridge says.

Of course, the same rules about supervision and safety apply, regardless of the child's size.

Joe Pillarella says he would advise other teens to take it slowly when they start weight training. "Start off light and slowly increase your weight as your body allows you to," he says.

Here are the AAP's tips for any kind of strength training:

  • Take it easy. At first, there should be ''no load," or no resistance, while learning the exercise. Add weight in increments of 10% only after 8 to 15 repetitions can be done.
  • Focus on technique. It's better to do the exercise correctly than to do more repetitions or to take on more resistance.
  • Ensure proper supervision and safety. The AAP says instructors or personal trainers should be certified and should have specific qualifications in pediatric strength training.
  • Don't lift weights rapidly or do "explosive" lifting. The AAP discourages power lifting and body building until someone reaches physical and skeletal maturity.
  • Strengthen all major muscle groups, including the core muscles.
  • Warm up and cool down. Devote 10-15 minutes to your warm up and another 10-15 minutes to cool down after strength training.
  • Remember, strength training is just one part of fitness. Don't overlook aerobic conditioning. And be sure to stay properly hydrated and eat a nutritious diet to help muscles recover.