June 5, 2001 -- Kids of all ages are lifting free weights, trying to bulk up for sports or to look like their favorite athletes. But how safe is all this strength training for children and adolescents? And what exactly is the difference between strength training and weight lifting?
To help parents make sense of it all, a policy statement issued this week by the American Academy of Pediatrics outlines the risks and benefits of strength training. The report appears in the June issue of Pediatrics.
"We support anything that gets kids to become active and stay physically active -- and that doesn't cause injuries -- and strength training can be all those things," says study author Bernard Griesemer, MD, a pediatric sports medicine specialist at HealthTracks Training Center of St. John's Health System in Springfield, Mo.
"Especially for middle and high school students, this kind of training can help with sports performance," says Griesemer. It's especially popular in sports like football, where size and strength are desirable, he says, but it does not help much to enhance running speed or jumping ability.
So what's the difference between strength training and weight lifting?
Strength training, also known as resistance training, uses resistance methods -- like free weights, weight machines, elastic tubing, or the person's own body weight -- to enhance muscle size and strength. Workouts involve a group of repetitions separated by rest periods, for example, three sets of 20 reps.
In weight lifting or power lifting, how much an individual can lift at one time is the focus. Many kids don't know the difference between strength training and weight lifting, and that gets them into trouble, says Griesemer.
During 1991-1996, children under 21 suffered an estimated 21,000-26,000 injuries each year using strength-training equipment, according to statistics from the Consumer Product Safety Commission. Muscle strains account for 40-70% of all injuries.
Other statistics show that at the middle-school level, high injury rates have been associated with weight lifting and power lifting. "These occur when there has not been appropriate training or monitoring of technique," Griesemer tells WebMD.
"Young athletes should avoid major competitive lifts," he says. "They should also be realistic about their expectations. These kids will not bulk up -- that only comes with puberty -- but they will gain strength, which is positive."
In some cases, in fact, strength training might not always be the best use of an adolescent's time, Griesemer tells WebMD. "Many youngsters are probably going to get more benefit from practicing and perfecting the skills of their sport than from strength training." Plus, strength-training programs are not effective for weight loss, especially for girls trying to lose weight, he adds.
Therefore, Griesemer recommends that younger athletes focus on a well-balanced exercise program, not just lifting weights. "They need to be getting aerobic exercise," he says. "Kids should have fun and stay physically active."
The American Academy of Pediatrics' recommendations include:
- Make sure a pediatrician sees the child before starting a strength-training program. A sports medicine specialist may be necessary in some cases.
- If general health benefits are the goal, add aerobic exercise to the child's fitness program.
- Every strength-training workout should include a warm up and cool down.
- Children should start training with no load, or weight. Once the exercise skill has been mastered, incremental weight can be added.
- Before increasing weight or resistance, they child must be able to successfully complete 8-15 repetitions in good form.
- A general strengthening program should involve all major muscle groups and the complete range of motion.
- Any sign of injury of illness from strength training should be evaluated before continuing the exercise.
To make strength gains, workouts must be at least 20-30 minutes long, two or three times per week, and continue to add weight or repetitions as strength improves, says the report. Strength training more than four times per week offers no additional benefit.
Just make sure the child's coach has proper credentials, says Griesemer. "We don't let anyone assist a young athlete unless they have a master's degree -- are skilled in working with kids and aware of pediatric muscle physiology."
The child's maturity is also an important factor, says Joe Chorley, MD, assistant professor of pediatrics and a sports medicine specialist at Baylor College of Medicine in Houston.
"I get the question all the time -- when is my child ready to do [strength training]?" Chorley tells WebMD. "They have to have a certain level of maturity to do it correctly. There's no specific age when they're ready."
Also, they need to do strength training for the right reasons. "Is it because some coach told the baseball team that they need to look like Mark McGwire? To look like a big athlete is not a good reason," Chorley says.
While strength training is more effective than weight lifting in building muscle, schools often put the focus in the wrong place, Chorley tells WebMD. "Unfortunately, when you get into high school football, on the weight room wall the sign says, 'How much can you lift at one time?' So there's a lot of pressure to lift as much as you can."
Weight lifting-related injuries occur because "their form just goes horrible," says Chorley. "They're stressing and straining, doing everything they can to get all this weight up, and their form goes right out the window. When that happens, kids get hurt."
"Good form is when you're controlling the weight and are able to be in control at any time," Chorley tells WebMD. "With free weights, it's making sure you have good control of the weight, you're pushing and pulling in the proper direction. You're not bouncing the weight or using your body in improper ways of leverage that puts stress and strain on muscles."
Injuries also occur when the gym does not have proper equipment sized for young athletes, Chorley says. "You put a 10-year-old kid in an adult gym, nothing is going to fit so there's no way their form is going to be good."
What causes major injuries -- falling or dropping a weight on a bone -- is "messing around in gyms," Chorley tells WebMD.
So, when kids are emotionally mature, when they're working out for the right reasons and having fun with it, Chorley says, "that's when they're more likely to stick with it."