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The Effects of Weight Training on Childhood and Adolescent Growth

Author: Joanna Xu

Editors: Hwi-On Lee, Viola Chen

Artist: Jade Li

“Weight training stunts your growth.” This is the typical parent’s response when their child shows interest in weight training. Whether you’re one of these disappointed children, or you’ve never even considered lifting, we’re here to address these misconceptions. 

In recent years, increased social media presence and exposure to children, from youth to adolescence, has popularized the idea of “hitting the gym”. This development was first encouraged when children were stuck at home during quarantine, forcing them to look towards other sources of entertainment and exercise. Whether it is the many “exercises for weight loss” videos on YouTube or just the general bodybuilder showing his physique on Instagram, the increased accessibility of these forms of media has encouraged many of the younger generation to pick up various types of exercise. Out of these, the one with the seemingly worst reputation is weightlifting. But why is it considered “bad”? The general idea is that the regular use of heavy weights disrupts growth. What research has found, on the other hand, suggests the opposite. 

In a sports medicine study, the results showed that resistance exercise, such as weightlifting, affected hormonal activity in the study’s subjects. This hormonal response just so happened to be related to tissue growth and remodeling, which suggested that rather than stunting growth, weightlifting may have actually stimulated it. Specifically, researchers found a significant jump in anabolic hormones such as testosterone, which promotes growth in bones and muscles, as well as growth hormones (GH) in the 15-30 minutes following exercise. This is significant not only for the drastic role that testosterone plays in growth, but also because of the influx in GH, which is the family of hormones that fuels childhood growth and helps with tissue and organ maintenance throughout your lifetime. As a matter of fact, doctors will often prescribe synthetic growth hormones to help children with impaired hormone levels grow. Since weight training is able to stimulate the release of growth hormones naturally, we can see that rather than stunting our growth, weight training may boost it instead.             

In addition to increasing the release of growth hormones, weight training also serves to reduce the hormones that work against it. This is because the extra calories burned during exercise cause a decrease in body fat composition while increasing muscle volume over time. Adipose tissue, otherwise known as fat, is responsible for creating aromatase, the enzyme that converts testosterone produced by our bodies into estrogen, which is responsible for the development of female sexual characteristics as well as the maintenance of the  female sexual and reproductive health. With the decrease of adipose tissue, one can then decrease the production of aromatase, resulting in greater levels of testosterone and lower levels of estrogen. What many don’t know, however, is the role estrogen plays in growth. When it comes to bone growth, estrogen signals the closure of growth plates, also known as epiphyseal plates. The growth plates, a cartilaginous portion at the ends of long bones such as the femur, tibia, and fibula in your legs, are where bone growth takes place. When estrogen causes these areas to “close,” growth ceases for the time being. Since women naturally have higher levels of estrogen, they are typically shorter. When they start weight training, however, these estrogen levels decrease, and their increased testosterone is able to stimulate Insulin-like Growth Factor 1 (IGF-1), a hormone that manages the effects of  GH on your body.  This reason is also why one will often see drastic differences in men after a period of weight training in comparison to women who have been training for a similar period of time. Either way, there is substantial evidence to suggest that weight training does not stunt growth, whether it is in boys or girls. 

Based on these studies, it is safe to say that there is little correlation between weight training and an inability to grow. Rather than prevent growth, it has been proven that weightlifting actually aids in the process of childhood growth. Of course, it is still important to be careful when it comes to weightlifting since ego lifting and improper form can lead to joint issues among other potential problems. However, risks aside, weightlifting may not be what parents initially thought. In fact, it may be better than anything they could have imagined, given its benefits, such as strength and muscle building, bone growth, and overall joint health. So next time you hear an adult say, “Weightlifting stunts growth,” make sure to correct them!

 

Citations:

Pierce, Kyle C et al. “Weightlifting for Children and Adolescents: A Narrative Review.”

Sports health vol. 14,1 (2022): 45-56. doi:10.1177/19417381211056094 

Kraemer, William J, and Nicholas A Ratamess. “Hormonal responses and adaptations to

resistance exercise and training.” Sports medicine (Auckland, N.Z.) vol. 35,4 (2005): 339-

61. doi:10.2165/00007256-200535040-00004 

Gharahdaghi, Nima, et al. “Links between Testosterone, Oestrogen, and the Growth

Hormone/Insulin-like Growth Factor Axis and Resistance Exercise Muscle

Adaptations.” Frontiers, Frontiers, 18 Dec. 2020,

Ağırdil, Yücel. “The growth plate: a physiologic overview.” EFORT open reviews vol. 5,8

498-507. 10 Sep. 2020, doi:10.1302/2058-5241.5.190088

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