As long as proper technique is used, lifting weights is completely safe. The belief that it might stunt growth is completely false.
As children age, their bones lengthen. In-between the bones, is where the growth plates are located (called epiphyseal plates). When signaled by the brain through a hormonal process, the epiphyseal plates extend the bones overtime, until puberty is finished. At that time, with the hormone estradiol, the growth plates are closed, and the height of the individual is set. For this reason, height growth is purely hormonal. The only way strength training could affect growth would be if the bone itself would break, which is almost impossible, and far more likely to happen with more common sports.
Health care and fitness professional groups – including the American Academy of Pediatrics, the American College of Sports Medicine, the American Orthopaedic Society for Sports Medicine, and the National Strength and Conditioning Association agree that a supervised strength training program that follows the recommended guidelines and precautions is safe and effective for children [1-5]
If a child is interested in strength training, it should be encouraged. Children of all ages can safely exercise in the weight room, as long as it’s supervised and the training program is individualized. Proper exercise progression should be used, and there’s little benefit to having a program with high volume, high frequency, or sets taken to failure. Proper technique should be emphasized, and the goal should be adherence above everything else. Weight-lifting has many benefits for health and wellness, such as improved coordination, strength, bone density and even cardiovascular fitness. Therefore, it’s of high importance to make sure the child enjoys the training provided, so that a habit is built from a young age, and the individual can enjoy the benefits of strength training for many decades to come.
There’s no minimum age required, but around 7 or 8 years of age is a good guideline, assuming the child is interested. A simple routine consisting of 1 to 2 sets of compound movements (such as goblet squats, rows, Romanian deadlifts etc) 2 times per week is a good starting point. It should be adjusted depending on the individual needs and preferences.
In a world where inactivity is becoming the norm, strength training shouldn’t be discouraged based on myths without any evidence supporting it.
 American Academy of Pediatrics Committee on Sports Medicine and Fitness Strength training for children and adolescents. Pediatrics. 2008;121:835-840
 American College of Sports Medicine Current Comment: Youth Strength Training. Indianapolis, IN: American College of Sports Medicine; 1998
 Cahill BR. American Orthopaedic Society for Sports Medicine: Proceedings of the Conference on Strength Training and the Prepubescent Chicago, IL: American Orthopaedic Society for Sports Medicine; 1998
 Faigenbaum AD, Kraemer WJ, Cahill, et al. Youth resistance training: Position statement paper and literature review. J Strength Cond Res. 1996;18:62
 Schafer J. Prepubescent and adolescent weight training: is it safe? Is it beneficial? J Strength Cond Res. 1991:13:39
Originally posted on: