Taking Aim at the “Lifting Weights Stunts Kids’ Growth” Myth

Back in the day, athletes in many sports used to avoid the weight room, fearing that resistance work was going to make them “bulk up” too much, compromising their ability to run, jump, or whatever their activity required. This is just one of many myths that surround strength training. Another one I see all the time online is that kids shouldn’t lift weights because it will stunt their growth, damage their joints, and place too much stress on their still-growing skeletons. In this article, we’re going to put such claims under the microscope. So if you’re a young athlete, a sports parent, or someone who coaches junior competitors, read on. Back in the 1950s and 60s, physical education was still rooted in running, calisthenics, rope climbing, and the like. There’s nothing wrong with such modalities and in fact, today’s PE programs would benefit from incorporating more of them (and bringing back the trusty pegboard, as CrossFit did a few years ago). Yet at this point, weightlifting was still largely misunderstood. It wasn’t until research out of the Soviet bloc made it to the West that people finally started to sit up and take notice of the many potential advantages that strength training can offer. Still, such training wasn’t considered safe for kids, and myths developed about how it would halt their development, harm their growth plates, and possibly even break their bones. Despite these misgivings, there is now a scientific consensus that resistance training is not harmful to children.

In an article for the American College of Sports Medicine, Avery D. Faigenbaum, Rhodri S. Lloyd, and Jon L. Oliver stated: “No scientific evidence indicates that participation in a well-designed youth resistance training program will stunt the growth of children or harm their developing skeleton. In fact, childhood seems to be the best time to participate in strength-building activities that enhance bone mineral content and density. With qualified supervision and a sensible progression of training loads, regular participation in youth resistance training can have a favorable influence on bone growth and development in girls and boys.”

Reducing the Risk of Injury and Concussion

A group of exercise physiologists followed the progress of 52 young soccer players over the course of an entire outdoor soccer season. Out of the first group of 26 that did no resistance training, 17 sustained at least one injury. Yet only four of the 26 that did three strength sessions per week in four, three-week blocks got hurt. The latter group also performed better in sprinting, jumping, and an agility test. The authors concluded that “strength training accurately and efficiently scheduled in youth soccer players, induced performance improvement, and reduced the rate of injuries.”

Doing regular resistance work in the gym also appears to benefit young people who play sports with high strength, speed, and power requirements. Researchers from the University of Bath in England tracked 3,188 rugby players aged between 14 and 18. The program that half the participants underwent consisted of “balance training, whole-body resistance training, plyometric training, and controlled rehearsal of landing and cutting maneuvers” with the goal of “Conditioning the musculoskeletal system to tolerate external forces, through enhancing strength and movement control.”

The group that followed a resistance training program reduced contact and non-contact injuries in competitive play by a whopping 72 percent overall, with 81 percent fewer upper limb incidents than the control group. Players who regularly performed resistance training also experienced 59 percent fewer concussions, which the study authors attributed to stronger neck muscles. Though the intervention group was supposed to do three resistance training sessions a week, they averaged just two, showing the positive impact that a minimum training input can have on injury outcomes.

Boosting Physical Performance

The benefits of a well-balanced resistance training program aren’t limited to reducing injury and concussion risk. A review published in Frontiers in Physiology noted that regular resistance training helped improve throwing, kicking, serving, jumping, and other sports-related outputs in a variety of activities. The authors noted that a combination of plyometrics and resistance exercises was most effective in increasing jumping and other kinds of power-dependent movements.

If kids are willing to stick with it (and self-motivation is a significant factor in determining the long-term success of any child’s exercise program), resistance training can also yield significant strength dividends. A group of German exercise physiologists conducted a two-year study on young athletes and found that those who trained twice a week over several periodized blocks with breaks in between improved their front and back squat by a startling 230 to 250 percent. They also got faster, improving their sprinting performance over a 30-meter distance by an average of six percent.

A review published in the British Journal of Sports Medicine concluded that “Stronger young athletes will be better prepared to learn complex movements, master sport tactics, and sustain the demands of training and competition. An integrative training program grounded in resistance training and motor skill development can optimize a young athlete’s potential to maximize their athletic and sporting performance while reducing the risk of a sports-related injury.”

Despite all the evidence presented in this post, I’m not advocating for taking your toddler into the gym and putting them in a squat rack with a loaded barbell. That being said, research conducted by Ratey and many others show that young kids improve overall development when they’re involved in active play daily. Once a child is seven or eight, they should be coordinated enough to join you in doing some bodyweight movements like air squats, planks, jumping jacks, and pushups.

As with an adult who’s beginning a new exercise program or has a low training age, it’s best to begin slowly and make sure kids get basic movement patterns like a hinge, lunge, squat, vertical and horizontal push, and pull down. From there, you can start to layer on a little more load, intensity, and volume as they enter adolescence, to complement whatever sports they’re already playing in either informal settings like pickup basketball or formal ones such as a soccer league. Doing sessions for 20 to 45 minutes two to three times a week should allow them to explore and get competent at performing a wide variety of movement patterns.

Once they’ve got unweighted movements and static holds (isometrics) down, then you could have them use a TRX Suspension Trainer, which will challenge their stability and balance while still providing a safe training experience. Low-level plyometrics like hopping, bounding, and skipping rope not only start to develop young athletes’ speed and power but can also make their joints and connective tissues stronger ( check out our recent article for more on how strength training does this). Plus, these exercises are lots of fun.

When a child transitions into their teenage years, they should be ready to handle a little more load, assuming that you’ve helped them lay a solid movement foundation. As the Frontiers in Physiology study authors put it, “physiological reasons may also explain the larger adaptive potential in adolescents compared to children because adolescents have larger muscle mass and type II fibers compared to children.” Kettlebells, dumbbells, and even lighter barbells can become appropriate training tools at this point, as long as you take a careful approach, supervise training at all times, and back off if the combined load of sports-specific practices, resistance training sessions, and games/meets becomes too much to handle.

Check back soon for part two, in which we’ll explore how regular exercise helps kids improve emotional control, overcome behavioral and mental health issues, and increase academic performance.

[i] Avery D Faigenbaum, Rhodri S Lloyd, and Jon L Oliver, “Myth: Lifting Weights is Unsafe for Children and Will Stunt Their Growth,” American College of Sports Medicine, March 25, 2020, https://www.acsm.org/all-blog-posts/acsm-blog/acsm-blog/2020/03/25/mythbusting-youth-resistance-training.

[ii] Sghair Zouita et al, “Strength Training Reduces Injury Rate in Elite Young Soccer Players During One Season,” The Journal of Strength and Conditioning Research, May 2016, available online at https://pubmed.ncbi.nlm.nih.gov/26918277/.

[iii] Michael D Hislop et al, “Reducing Musculoskeletal Injury and Concussion Risk in Schoolboy Rugby Players with a Pre-Activity Movement Control Exercise Programme: A Cluster Randomised Controlled Trial,” British Journal of Sports Medicine, May 17, 2017, available online at https://bjsm.bmj.com/content/51/15/1140.

[iv] Urs Granacher et al, “Effects of Resistance Training in Youth Athletes on Muscular Fitness and Athletic Performance: A Conceptual Model for Long-Term Athlete Development,” Frontiers in Physiology, available online at https://www.frontiersin.org/articles/10.3389/fphys.2016.00164/full.

[v] André Sander et al, “Influence of a 2-Year Strength Training Programme on Power Performance in Elite Youth Soccer Players,” European Journal of Sport Science, November 13, 2012, available online at https://www.tandfonline.com/doi/abs/10.1080/17461391.2012.742572.

[vi] Avery D Faigenbaum et al, “ Citius, Altius, Fortius: Beneficial Effects of Resistance Training for Young Athletes: Narrative Review,” British Journal of Sports Medicine, December 23, 2015, available online at https://bjsm.bmj.com/content/50/1/3.

Tim DiFrancesco, PT, DPT spent 6 seasons as the Head Strength & Conditioning Coach of the Los Angeles Lakers and is the founder of TD Athletes Edge. He is nationally renowned for his evidence-based and scientific approach to fitness, training, nutrition, and recovery for athletes and fitness enthusiasts.

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Originally published at https://blog.tdathletesedge.com.