For decades, a common belief has persisted that lifting weights at a young age can halt or limit a person’s final adult height. This concern often surfaces when young athletes or children show interest in resistance training, which includes any activity that forces muscles to contract against an external resistance, such as free weights, machines, or bodyweight exercises. Parents and coaches frequently worry that this activity will interfere with a child’s natural growth process. To address this concern, it is necessary to examine the biological structures involved in height development and determine what current scientific evidence says about strength training.
The Biological Foundation of Height
The foundation for this enduring myth lies in a misunderstanding of the anatomy responsible for longitudinal bone growth. Height increases primarily due to the activity occurring in specialized areas of cartilage located near the ends of long bones, known as the epiphyseal plates, or growth plates. These plates are essentially factories of new bone tissue, where cartilage cells continually divide and are then replaced by hardened bone, causing the bone to lengthen. This process continues throughout childhood and adolescence.
The growth plates are softer and more vulnerable to injury than the mature bone surrounding them. They remain active until the end of puberty, when hormonal changes cause the cartilage to fully ossify, or harden, into solid bone, a process called physeal closure. Once the growth plates close, the long bones can no longer increase in length, and the individual has reached their final adult height. Because these plates are the weakest point in the developing skeleton, severe trauma to a growth plate could theoretically lead to a disturbance in bone development.
Addressing the Stunted Growth Myth Directly
Scientific research and the consensus from major medical and sports organizations clearly state that properly supervised strength training does not stunt growth. Organizations like the American Academy of Pediatrics (AAP) and the American College of Sports Medicine (ACSM) confirm that resistance exercise, when appropriately prescribed, has no measurable negative impact on a youth’s growth potential or growth plate health. Moderate, controlled loading of bones through resistance exercise can have positive effects, such as increasing bone mineral density. This strengthening effect helps build a more robust skeleton, beneficial for long-term bone health.
The fear of stunted growth stems from a conflation of controlled exercise with acute, traumatic injury. Damage to a growth plate that could cause a growth disturbance typically results from a sudden, uncontrolled impact, such as a severe accident, an awkward fall, or dropping a very heavy object. The issue is excessive, acute force applied incorrectly, not the act of lifting a weight under control. An injury to a growth plate from a weight training program is rare and almost always linked to lifting an inappropriate load with poor technique or a lack of supervision.
The vast majority of studies show that the risk of growth plate injury in supervised strength training is significantly lower than the risk of injury in common youth sports like soccer, football, or basketball. The controlled environment and predictable movements of a well-designed resistance program offer a safer alternative for developing strength and coordination compared to the chaotic nature of many competitive team sports. A properly executed strength program can also reduce the risk of sports-related injuries by strengthening muscles and connective tissues that support the joints.
Actual Risks of Youth Strength Training
While the risk of stunting growth is negligible with appropriate practice, youth strength training is not entirely without risk, though the actual injuries are generally minor. The most common issues seen in young athletes are soft tissue injuries, which include muscle strains and ligament sprains. These injuries typically occur when a child attempts to lift a weight that is too heavy for their current strength level or uses incorrect form for an exercise.
Overuse injuries are another risk, often manifesting as tendinitis or specific conditions like Osgood-Schlatter disease in the knee. These problems arise from repetitive stress on a muscle or joint without adequate rest and recovery time. Poor program design that increases training volume or intensity too quickly, without allowing the body to adapt, is a major contributing factor to overuse issues. These risks are comparable to those found in any repetitive physical activity, and they are largely preventable through education and sensible training practices.
Guidelines for Safe Youth Strength Training
A successful and safe strength training program for children and adolescents must place an absolute priority on proper technique over the amount of weight lifted. Young athletes should begin by learning movements with no external resistance, using only bodyweight or a very light bar, to ensure mastery of the correct form. Once the technique is consistent and repeatable, resistance can be gradually added.
Mandatory qualified adult supervision is non-negotiable for all strength training sessions. The instructor should be experienced in working with youth and possess the expertise to correct form instantly and adjust loads appropriately. A general guideline is to use a light resistance that allows the child to comfortably complete 8 to 15 repetitions of an exercise with perfect technique. Progress should be tracked by gradually increasing the number of repetitions or sets first, and then slowly increasing the resistance.
The training schedule should be balanced, incorporating flexibility and aerobic activities in addition to resistance work, and should allow sufficient time for rest between sessions. Before beginning any formal strength program, a young person should receive medical clearance from a physician. Competitive lifting, such as maximal single-repetition lifts or powerlifting, should be avoided until an individual has reached skeletal maturity, which typically occurs after the pubertal growth spurt is complete.