The idea that lifting weights as a child or adolescent can permanently halt or stunt height growth is a persistent and common concern. This query arises from a misunderstanding of how the human skeleton grows during the years of rapid development. Modern scientific research and major pediatric health organizations have provided a clear, evidence-based answer. This analysis explores the biological structures responsible for growth, addresses the origin of the myth, and outlines the proper, safe approach to youth resistance training.
Understanding Growth Plates
The basis for the myth lies within the mechanics of bone lengthening, which occurs at specialized structures called growth plates. These are areas of developing cartilage situated near the ends of long bones, such as the femur, tibia, and bones in the forearm. These plates are responsible for all longitudinal bone growth, determining a person’s final height.
The growth plate is composed of cartilage cells that continuously divide and mature, eventually being replaced by hard bone tissue. This process continues throughout childhood and adolescence. Once a child reaches skeletal maturity—typically around ages 13 to 15 for girls and 15 to 17 for boys—the cartilage is completely replaced by solid bone. This process is called fusion or “closing” of the growth plates. When the plates close, the bones can no longer lengthen, and height growth stops.
Directly Addressing the Stunted Growth Myth
Decades of research have shown conclusively that properly structured and supervised resistance training does not impede linear growth or damage the growth plates. The fear that weightlifting stunts growth likely originated from early observations of injuries in unsupervised, competitive youth weightlifting, or from conflating resistance training with general traumatic accidents. In reality, the risk of injury from organized, supervised resistance training is lower than in many common youth sports like soccer or football.
The American Academy of Pediatrics (AAP) and other major medical organizations confirm that resistance training is safe and beneficial for children when managed correctly. A properly designed program focuses on technique and controlled movements, which strengthens the surrounding muscles, tendons, and ligaments, offering a protective effect to the joints and growth plates. This strengthening of the supporting structures can lead to increased bone mineral density and enhanced resistance to injury.
A review of experimental training programs found that resistance training did not negatively impact the growth in height and weight of pre- and early-pubertal youth. The positive stress applied by moderate resistance training encourages the musculoskeletal system to adapt and strengthen without disrupting the cellular process of bone lengthening at the growth plate. The primary risk to the growth plate is not the physiological act of lifting itself, but an acute, high-impact injury resulting from poor technique or dropping a heavy weight.
Essential Safety Guidelines for Youth Resistance Training
Since the myth of stunted growth is debunked, the focus shifts entirely to injury prevention, primarily through proper form and supervision. All youth resistance training must be overseen by a qualified adult, such as a certified strength coach or physical education teacher, to ensure safety and correct technique. Supervision is necessary because young participants may overestimate their physical abilities or lack awareness of inherent risks.
Training programs must prioritize learning the correct form and movement patterns before any external weight is introduced. Children should begin with bodyweight exercises or very light resistance to build a foundational understanding of the movement. Progression should be gradual, focusing on lower intensity with higher repetitions, typically 8 to 15 reps for 2 to 3 sets per exercise.
Maximal lifts, such as attempting a one-repetition maximum (1RM), should be avoided until a child has reached full physical maturity. High-intensity activities like competitive powerlifting or bodybuilding are generally not recommended for preadolescents. Every session should also include a dynamic warm-up before exercise and a cool-down with stretching afterward.