It can be a weighty decision for parents. Should their children be allowed to work out with weights? If so, at what age? What are the pros and cons?
The place to begin any discussion is to learn about the growth plate, an important part of the anatomy of children and teens.
According to the National Institutes of Health's National Institute of Arthritis and Musculoskeletal and Skin Diseases, the growth plate -- also known as the epiphyseal plate or physis -- is the area of growing tissue near the ends of the long bones in children and adolescents. Each long bone has at least two growth plates -- one at each end -- that determine the future length and shape of the mature bone.
When growth is complete during adolescence, the growth plates close and are replaced by solid bone. The growth plates are the weakest part of the growing skeleton and are vulnerable to injuries, often called fractures.
According to the NIH, one-third of growth plate injuries are the result of competitive sports such as football, gymnastics or basketball. Another 20 percent are caused by recreational activities such as skateboarding, sledding or skiing. An injury that would cause a sprain in an adult can cause serious injury in a child.
It is important that a child not do exercises or workouts that can damage the growth plate.
Len Saunders, who wrote his master's thesis on the subject, believes that children and teens can benefit from using weights.
"In my experience, you can use weights at almost any age. I've seen them start as early as 7 or 8. It shouldn't be controversial as long as they are used in a controlled manner," he says.
Weight training has a special appeal for young athletes. Saunders, the author of "Keeping Kids Fit," notes that some young people get interested in working out with weights when they see others using them.
"For example, the freshmen on a high-school football team may look at the seniors who work out with weights. They figure, 'If they can do it, so can I,' but don't realize the older guys have been doing it for quite a while," he says.
Marc Sickel, founder of Fitness for Health, recommends that kids not use weights until about seventh grade because their bodies are still changing and maturing. Experts agree that weight training must be done properly under the supervision of a qualified trainer.
Weight machines are now being specially designed and made for children. Even if they are too young to lift weights, children can do other workouts that will help them develop physically.
Sickel recommends children at younger ages use their own body weight, performing isometric exercises like squats and pushups or using bands that leverage the child's own flexibility.
"I'm all for kids starting early, especially as the childhood obesity rate rises in this computer/video game age. Proper exercise at a young age can help build the foundation for success in any future weightlifting or sports endeavor," says James Cipriani of Cutting Edge Personal Training.
He adds that parents should not confuse strength training with weightlifting.
"Intense weightlifting and training with the goals of increasing muscle mass is not recommended for kids. According to MayoClinic.com, they can cause strain to young muscles, tendons and growth plates," says Cipriani.
Training in a more intense manner and/or with the goal of stimulating muscle gains should be left till they start going through the hormonal changes of puberty. Anything before that should be focused on improving basic endurance and strength."
Kids as young as 7 can start building strength through bodyweight activities, such as pushups, pull-ups and crunches.
"It is imperative that they practice proper form and techniques," he says.
The bottom line is that parents must be vigilant in overseeing any weight training done by their children.
"If a parent is unsure what is the correct technique for his or her own child, consult a qualified fitness professional who can design and help implement age-appropriate sports training or fitness programs that can reduce the potential of injury while making physical activity fun," advises Sickel.
"Parents have to be careful to ensure their child is not overtraining and using weights at too young an age."