Children as young as 7 can benefit from lifting weights -- but only if they follow programs specifically designed for their age group, say Avery Faigenbaum and Wayne Westcott in their new book, "Youth Strength Training" (Human Kinetics, August 2009).
A professor in the department of health and exercise science at the College of New Jersey, Mr. Faigenbaum has written seven books related to youth fitness. Mr. Westcott is a fitness research director at the South Shore YMCA in Quincy, Mass., and an adjunct professor of exercise science at Quincy College.
In the past, children have been discouraged from lifting weights because of the risk of doing harm to their growing bones. But children who do strength training increase bone mineral density at a rate several times faster than children who don't lift weights, Mr. Faigenbaum and Mr. Westcott say.
Dr. Jeanne Doperak, a primary care sports medicine physician at UPMC, agrees.
"Historically, there was some thought in the sports medicine world that strength training among pre-adolescents would damage growth plates," she said. "And what was the point? Because pre-adolescents don't have the hormones necessary to build muscle mass. Over the last 10 years we've pretty much proven that's false."
"There is a lot of new literature coming out that says it is beneficial for kids to do it," said Dr. Sam Akhavan, a sports medicine physician for the West Penn Allegheny Health System who runs the Human Motion Training Academy Allegheny General Hospital has established at the Sportsplex in Green Tree.
"Strength training does have benefit, not only with strength, but with balance, increased bone density and self esteem," Dr. Doperak said. "The kids feel better about themselves.
"There are a lot of sports that have a higher rate of growth plate injury -- like Little League baseball," she added.
Strength training seems to be especially beneficial for overweight children, Mr. Faigenbaum said, because they often prefer resistance training to other forms of exercise, and do better at it.
But watering down an adult strength training regimen can be dangerous, the authors said.
"Because of variations in maturation, training age and stress tolerance, youth strength training programs need to be prescribed and progressed carefully," Mr. Faigenbaum said.
In their book, Mr. Faigenbaum and Mr. Westcott offer strength training regimens for 7- to 10-year-olds, 11- to 14-year-olds, and 15- to 18-year-olds.
With children, proper exercise technique is far more important than the amount of weight lifted, or the number of repetitions, they said.
Dr. Doperak agreed. "It has to be a supervised program, emphasizing technique over power. A 7-year-old shouldn't max out in the weight room."
"The motto is to start low and go slow," Dr. Akhavan said. "Once you have the technique down, you can increase the weight very slowly. You should be able to do six to 15 repetitions fairly easily. If the kid is straining, lower the weight."
For most youngsters, exercise machines are better for resistance training than free weights, Dr. Akhavan said.
Weight can be raised in lower increments with free weights, he said, "but the problem with free weights is you need a lot of balance and coordination to do it."
How young is too young?
"As a general rule of the thumb, the child has to be able to follow directions and demonstrate adequate balance," Dr. Doperak said. "For most kids, that's around age 7 or 8."