M.D. 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, but they should be supervised and not lift qweights that are heavier than they can lift 10 times in a row. 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.