Strength training exercises with weights should not be undertaken before a child has developed appropriate balance and posture control, which typically happens around age 7 or 8. Parents whose children are of appropriate age and have the desire to lift weights can take some steps, including consulting with a pediatrician and finding an educated and knowledgeable trainer, to ensure that their child will be undertaking this activity safely.
While it is safe for children above a certain age to lift weights with proper supervision, it is important for the adults overseeing this activity to ensure the child is not pushing him or herself too hard in pursuit of big lifts. Children should not be driven to compete and push their limits with weightlifting. Proper technique should be emphasized above bigger lifts. The biggest health and safety concern in this area is to avoid permanent damage to growth plates and other tissue that has not finished developing, which could hinder a child's ability to properly grow and develop. Overall, it is important for children to be supervised when lifting weights, and the focus should be on building strength and developing proper form rather than adding muscle mass.