An article in the journal from the American College of Sports Medicine shows that just four weeks of hard exercise in growing animals increases bone mass. That means that children who start training while they are still growing will have a great advantage over athletes who start training after puberty.

Turkey's Naim Suleymanoglu is the greatest weightlifter who ever lived, has won three Olympic championship. He started lifting weights when he was eight in Bulgaria. In most sports the strongest athlete wins. Muscles can only grow to be as strong as the strength of the bones on which they attach. People with the biggest bones are the ones who can grow the biggest muscles. People who start lifting weights when they are young will have the biggest bones and therefore the capability to grow the largest muscles. However, all children in weight-lifting programs should be supervised and should not lift weights that are heavier than they can lift 10 times in a row without shaking or losing form.

Why then does a Committee of the American Academy of pediatrics recommend against young children training for competitive sports, even though there is no evidence that young children are more likely than adults to injure themselves?

There is no data to show that hard exercise damages growth centers in bones to interfere with growth. There is no evidence that growing larger muscles stunts growth. However, there is great concern that some children will be subjected to abusive coaches and inconsiderate parents who place athletic training above the child's own wishes and desires. In one study from Southern California, 90 percent of female cross country runners under age nine stopped running before they reached high school. The concern about serious athletic training for young children is more mental than physical. Children should not begin serious athletic training unless they want to do it, that they take days off from training regularly and when they want to, and that their coaches and parents allow them to be children. As far as their bodies are concerned, young children can start training at a very young age for athletic competition, but as far as their minds are concerned, they should not train before they are ready to accept the regimented lifestyle required for athletic competition.

Gabe Mirkin, M.D.

Dr. Gabe Mirkin has been a radio talk show host for 25 years and practicing physician for more than 40 years; he is board certified in Sports Medicine and three other specialties.

Dr. Mirkin's daily features on fitness have been heard on CBS Radio News stations since the 1970's. He has written 16 books including The Sportsmedicine Book, the best-selling book on the subject that has been translated into many languages. His latest book is The Healthy Heart Miracle, published by HarperCollins.

Dr. Mirkin is a graduate of Harvard University and Baylor University College of Medicine. A Boston native, Dr. Mirkin did his residency at the Massachusetts General Hospital. He has served as a Teaching Fellow at Johns Hopkins Medical School, Assistant Professor at the University of Maryland, and Associate Clinical Professor in Pediatrics at the Georgetown University School of Medicine. He has run more than forty marathons and is now a serious tandem bicycle rider with his wife, nutritionist Diana Mirkin.