Is Lifting Weights Safe for Kids?

Every now and again I’ll see someone post a question on social media.

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When is it ok for my son/daughter to start working out?
— Facebook friend

And most times I show good restraint by not weighing in on social media posts, especially ones that involve hot button issues such as politics and religion. 

However a question on strength and conditioning is another story and falls into my wheelhouse and area of expertise. Unless of course the question was whether I believe the pope deadlifts with a conventional or sumo stance? The answer of course is conventional and no further debate is needed.

So after passing on my advice to my friend I thought I would organize my thoughts and provide some references to back up the claims. Here is what you need to know about resistance training (RT) for young athletes. This includes why RT is a good idea and how effective it can be, what the risk factors are, some considerations as to when RT is age appropriate, some guidelines for RT, how plyometrics can be incorporated into a program and some things to keep in mind regarding training males and females.

Is RT for youth a good idea? And how effective can it be?

At our gym we see two main reasons young athletes look to get started with RT. The first is to improve sports performance. They see what their idols do and look to emulate them. My generation grew up with Michael Jordan and the ‘Be Like Mike’ tagline applied to everything MJ did including training in the gym. 

And if not for sports performance young people tend to want to hit the gym to improve their health or address an injury. 

What the research tells us is that the complex neural adaptations required with RT make childhood an ideal time to start (1, 3, 4, and 10). There are huge benefits in terms of bone health and we can also see a decrease in injury and disease later in life (2). This is kind of like an insurance plan whereby making the investment in RT at an early age can offset some of the health problems that may arise later in life.

In terms of the effectiveness there is no doubt that children and youth that participate in a RT program develop more strength than those who don’t. Besides the physical changes that occur there are also psychosocial developments that happen with training of this type. Lastly, RT has been shown to be effective in improving functional movements (1, 3, 4, and 10). In other words, young people involved in a RT program become more athletic as a result.

 

 

But is it safe? 

When the topic of RT for youth comes up there are typically two groups with very strong viewpoints on the topic.

There is one group that recognizes the benefits that could be available to a young person getting started in a RT program. And then there is the second group that believes RT for children is unsafe, leads to injuries and should be saved until full physical maturation, or even later. I say later because recently we consulted with a young athlete almost done high school who was told to avoid RT until they were finished growing for fear of injury. This is unfortunate as this athlete is developmentally ready for RT and is missing out on many of the benefits associated plus may be at an increased risk for injury by being weaker.

In terms of injuries and RT for pre-adolescents and adolescents most of the claims of injuries trace back to the 1970s and 1980s (10).

If we think back to these times, this was the decade when Arnold Schwarzenegger won his seven Mr.  Olympia titles and the popularity of the Nautilus equipment took off. It’s not too much of a stretch to picture young athletes trying to use machines designed for adult-sized bodies or following training programs of bodybuilders taking steroids. It’s not surprising that injuries would follow.

What is interesting is that the prevailing opinion of RT being risky for children or young athletes really took hold in the 70s and 80s, as mentioned. However, if we are to be evidenced-based and guided by what the research tells us, and not our emotions, there is a different story. Research on children and RT was first published in 1986 and studies of plyometric training and children originated a little later in 1999 (10). 

The concern of RT for young athletes typically focuses on growth cartilage and the impact on linear growth (3). I can remember as a young boy growing up to be careful with ‘working out’ as I might get injured and it might stunt my growth. So I didn’t really get started with resistance training and I shot up all the way to almost 6’ and have now had bilateral ACL reconstructions.

It’s hard to say what my growth and injury history would have been had I been introduced to weight training at an earlier age, but what is certain is that I wouldn’t make it as a forward on any basketball team and I can tell when the weather is changing.

A review of the literature shows that RT for young athletes is quite safe (1, 3, 4, 8 and 10). Instead of the risk it potentially poses to the growth cartilage and epiphysis, the opposite is actually true. At certain stages of a young person’s development there can be benefits of being exposed to the forces of RT. And compared to other sports RT has a much lower rate of injury compared to rugby, football and soccer. 

The risks of RT for children and adolescents relate to the program supervision, loading and other variables (4).  When properly supervised by a qualified professional, proper technique is used, with reasonable loading and progressions, RT can be quite safe for young athletes. 

So at what age can a young athlete start RT?

The short answer is when they are ready to play organized sport, they are ready for RT (1, 3, 6 and 10).

This involves both physical and mental readiness. When we consult with a young athlete and the parents in our gym I’ll ask most of the questions to the young athlete. I can look at someone and make a pretty accurate assessment as to their strength, mobility, fitness and athleticism just by the way they walk into the gym, their posture and the way they carry themselves. For example, a 12 year old hockey player that weighs 170 lbs, has a solid hand shake and is scanning our facility checking things out is different from the late bloomer 13 year old that shuffles in, keeps their head down and doesn’t want to be noticed. Both would benefit from a RT program but one may be more ready than the other.

What is harder to assess is what is going on inside their head. And so we’ll have a conversation, and I’ll ask them questions about who they are and what they like. I’ll ask what their goals are and why they want to get started. And I’ll ask about obstacles, nutrition, sleep and previous injuries. These can be tough questions sometimes even for an adult so I’m not expecting too much content-wise but instead I want to see how they communicate and if they do. It’s not uncommon for the athlete to instantly go mute and defer all answers to mom and dad.

If we had to assign ages to the readiness of RT, the youngest might be 6 years old (6, 10).

 


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At this stage of development, boys and girls can be doing the same things training-wise. And the elements of a program would include fundamental abilities such as agility, balance, coordination and speed. It can include athletic skills of running, jumping, throwing, catching, swimming and activities on snow and ice (6).

Obstacle courses can be a great tool at this age as well as hiking. We’ll regularly take our 5 and 7 year old girls out for hikes that require climbing loose shale, side stepping down steep pitches and sprinting down moderate grades when their mom isn’t looking.  This Fundamental Stage is appropriate for boys 6-9 years and girls from 6-8 years (6).

The next stage for young athletes is known as Learn to Train (6). We start introducing proper technique of the main lifts including squatting, pressing, pulling and hinging at the hips. Tools may include med balls, stability balls, bodyweight, bands, tubing, suspension trainers and more. In terms of age, athletes would be 8 or 9 through the onset of puberty. And at the pre-adolescent stage there is typically less risk with training compared to adolescents as the growth cartilage is stronger and more resilient to shearing forces (6). 

During the Learn to Train stage skill acquisition, as well as stamina and speed, are key aspects to develop (6). As a result, it is crucial that athletes develop as many athletic skills at this time as possible. Playing a wide variety of sports is crucial not only to optimizing development but also helps minimize burnout and repetitive strain injuries. Take a look at the top drafts in any major sport and you will see a trend that the top performers played multiple sports all the way through high school and in some cases into college as well. 

One thing parents can start doing with their kids is measure their height every 3 months from the age of 6 years (7). Then produce a graph with time on the horizontal axis (in months) and growth on the vertical axis (in cm).  At a certain age you will see a drop then an increase in growth. For example, maybe a young athlete was growing at a rate of 7 cm every 3 months. This may drop down to 5 cm then jump up to 9 cm. The point where the young person grows the most is known as their peak height velocity (PHV) and after this phase strength training is ideal for girls. Boys should wait 12-18 months. 

What are the guidelines for RT for youth?

Alright, so now that we know the benefit of resistance training for youth, and that it’s relatively safe for them to do, what does the program look like? What are some of the guidelines to keep in mind?

We should look at this as a marathon and not a sprint. And I mean that figuratively and not literally. I’m suggesting that we starting training all young athletes to compete in 26.2 mile races but instead that we should look at this as a process that will span their entire lives.

We want their first impression to resistance training to be so fun that they can’t wait to do it again. We want them to finish a session with a smile on their face, feeling proud for having learned or accomplished something and not being able to wait to share this with their parents and family. When we recognize something will have a positive impact on a young person’s life we want to ensure that they reap all the benefits of whatever it is continuing to take advantage of all the benefits for years to come. 

For example, imagine trying to get a young person to try a new food, specifically a vegetable. Now let’s say this vegetable was a Brussels sprout. And let’s say the Brussels sprouts had been left on the kitchen counter for a few weeks and had gone bad. But we still go ahead and cook them. In fact we boil them for a couple of hours and salt them heavily for feeding them to the young person. 

What are the chances this young person is ever going to want to eat Brussels sprouts again? 

We have to make sure the first taste (experience) is as positive and memorable as possible to leave them wanting more. Otherwise, it’s very possible to turn them off the idea of fitness and resistance training which can lead to unfulfilled athletic potential, possible injuries and a lifetime of health issues.

So put the coaching hat away to start and make the sessions fun. Disguise drills as games and include lots of variety (6). This is not the time to spend an entire session trying to teach proper technique for a lift. While we always want to move as well as possible don’t be too much of a stickler on technique where things momentum i.e. fun, grinds to a halt and it starts to feel like work.

To start out keep the frequency, volume and intensity lower. So this could look like 1-2 days per week, of 2-3 sets, 8-20 reps with bodyweight movements (1, 3, 4 and 10). 

Eventually this could progress to 2-3 days per week, of 3-4 sets per exercise with external loads at 50-60% of 1 RM (rep max) (1, 3, 4 and 10). The total exercises in a workout might be 8-12. All of the ranges should be on the lower side for younger athletes and athletes with a lower training age. For example, a 12 year that has been training for 2 years might handle more than a 13 year old just getting started.

Really take some time to groove the basics. Get good at squatting, hinging, pushing, pulling, ground work and locomotion.

 


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As for exercises to check each of these boxes, think of goblet squats, stability ball leg curls, push ups, pull ups, get ups and running technique.  An athlete that will spend the time work on and develop each of these qualities will be on the right track to minimizing injury and athletic performance.

The last thing to mention when it comes to the guideline of resistance training and young athletes is to slow down. By nature, young children are full of energy and like to move quickly. For example, have you ever seen a three year move around the house or a play ground? They don’t walk, they run. They don’t have anywhere they need to be like work or school yet they always have to run when they’re moving.

This carries over a little bit as young athletes get started with resistance training. And we don’t do ourselves any favours with the culture we’ve created. We’ve told young athletes to compete and reward finishing first. So what happens when you introduce a new exercise or drill to a group of young athletes? They race to see who can complete it first. This is exactly the opposite outcome of what we are striving for.

When young athletes start resistance training, really encourage them to go slowly on the eccentric phase (3, 4, 5 and 8). For example, when performing a push up, challenge them to take 5-10 seconds to lower their body to the ground. The same would apply on any resistance movement, loaded or just bodyweight, Resistance the pull of gravity as much as possible. 

As you focus on going slowly through the eccentric phase you give the young athlete a better chance to learn the movement. For a coach this also helps to spot technical flaws in movement and correct them before they become too ingrained. Athletes can also get stronger, sooner then they slow do on the eccentric phase. And as many injuries happen in this phase of the muscular contraction i.e. landing after a jump, we can greatly reduce the potential for injury.

As a coach, you can drill the eccentric phase by using an audible tempo count or by using a metronome so the athletes learn how slow to go. Incorporate different games like ‘Simon Says’ so must control and slow down movement. And remind them that nobody cares how quickly you can do a drill wrong.

What about plyometrics?

When a young athlete gets started with resistance training, pretty soon plyometrics enter the equation. Is this a good idea? Is it ok for young athletes to do plyos?

Back when I was studying for my credential as a strength and conditioning coach I remember reading a position statement regarding plyometrics and children. And basically the guideline was that children needed to be able to squat 1.5 times their bodyweight before they could start on a plyometric program. 

Well if you’ve ever checked out a playground with kids playing hop scotch you’ll see endless violations of this ‘training rule’. I don’t think anyone has ever checked to ensure all the kids hopping, skipping, bounding and jumping could squat 1.5 times their bodyweight.  And aside from regular accidents that can happen in a playground, hop scotch hasn’t resulted in significantly more injuries than any of the other schoolyard games.

 


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So plyos can be slowly introduced into a youth resistance training program. Because not only can these drills be safe to do they can also help lower the risk of injuries (5, 8). Younger pre-adolescent athletes can be benefit hugely as their growth cartilage can be stronger than adolescent athletes and more resilient to shearing forces (5).

Not only does the additional growth cartilage strength for pre-adolescents make this a good idea to start teaching some hops, skips, bounds and jumps but usually younger athletes have smaller masses than older ones (5,8,10). So it might more sense for the 10 year old by that weighs 95 pounds to be introduced to plyos than the 150 pound 13 year old. 

Starting out select bilateral (i.e. drills on 2 feet) before unilateral. Include options that take out the impact of gravity such as jumping up onto a box and then stepping down. Keep the volume low initially and this can measured in terms of the number of foot contacts with the ground. Put the emphasis on quality landings i.e. remember the section above that talked about developing eccentric strength. Use descriptive language and proper demonstrations before have athletes perform reps. Cues such as “the take off should look the landing”, “imagine landing on a carton of eggs”, “land as softly as you can”, “land as quietly as you can”, help convey the  concept of optimal force reduction to the young athlete. 

Sometimes plyos can be introduced to help with an athlete’s quickness. However this doesn’t maximize the potential benefits of plyos (5, 8). Plyos will help more with developing power than with enhancing speed (5, 8). So if a young basketball player wants to improve their vertical to one day dunk a basketball, plyos may help with this. However, if this goal is to move faster, then resistance training would be the better choice.

This is because when young athletes sprint they need to have enough strength, specifically lower body strength, to reduce the force of impact on the lead leg. If they aren’t strong enough they will yield to this force of impact and won’t be able to fully take advantage of the stretch-shortening-cycle. Additionally, most plyometric training for youth is done bilaterally, which is a good idea, yet sprinting is a unilateral activity furthering the rationale of plyos benefiting power more so than speed development. 

One last comment to make with plyometrics is that they are great to combine with a resistance training program. Younger, smaller athletes make respond well to them but be careful when introducing them to adolescent athletes that carry a greater mass yet haven’t developed the strength to go along with it. Plyometric training is also enhanced with balance and postural control. So a young athlete could do a few drills for their posture and balance first, followed by some plyometric training, would get the best results.

The difference between boys and girls

 In terms of whether boys and girls can do the same resistance and plyometric training the answer depends on the stage of development. Pre-pubescent boys and girls can train together and perform many of the same drills (2, 9). Girls can typically keep pace, and sometimes, outperform their male counterparts. Once puberty hits males have an advantage due to the extra androgens, mainly testosterone, lower average fat-mass and as well as differences at certain joint angles i.e. Q-angle.

Although boys benefit from an increase in testosterone at puberty that is not to say girls don’t benefit from resistance training. Female athletes that follow a resistance training program will become stronger than girls who don’t train (2). 

To be clear most of the research performed on young athletes has been with boys. This doesn’t discount the validity of the existing research however we need to be aware of this fact, and recognize the differences between boys and girls. For example, if a study included only boys from 5-9 years old, we may be able to predict similar outcomes when training girls of the same age. However, if a study looked at boys from 11-14 years old we shouldn’t expect similar results for girls.

Once puberty hits the changes between boys and girls are more evident. Boys will have an advantage on upper body strength exercises. And girls may need some more time working on eccentric strength and landing mechanics (2, 9). It’s also recommended at this time that boys and girls train separately if possible to eliminate the potential for behaviours that attempt to draw attention of the opposite sex.

Keep in mind as well the concept of absolute and relative strength when it comes to resistance training for girls. Relative strength refers to how strong you are in relation to your mass. For example, body weight exercises such as push up and pull ups can be good indicators of relative strength. Absolute strength on the other hand simply refers to the magnitude of the load that can be moved. For example, pressing 400 lbs on a leg press machine would be an example of absolute strength. 

When she is a younger, a female athlete may have higher levels of relative strength but lower levels of absolute strength. For example, a 105 pound 11 year old might be able to do 7 pull ups. Fast forward 5 years and this same athlete could weigh 145 pounds and struggle to do 4 pull ups. An ill-informed parent or coach might chalk this up to resistance training not being effective or of the athlete being lazy. At the same time this athlete at 16 years old might have increased their deadlift from 95 to 275 pounds.

The Bottom Line

Resistance and plyometric training can be very beneficial to young athletes for injury prevention, athletic development and reduced health problems later in life.

When a program is designed and overseen by a strength and conditioning professional the risk of injury is minimal. Athletes that are in organized sports, and possess the mental maturity may be introduced to a resistance and plyometric training program.

Start slowly with moderate loads, lower volume, teaching foundational movements on non-consecutive days. Put on a priority of developing eccentric strength and recognize when to adjust programming for boys and girls based on the stage of development.

By: Chris Collins MSc CSCS

Chris Collins is a strength & conditioning coach located in Kelowna BC Canada. He is the owner and head coach of Okanagan Peak Performance. He works with a range of athletes from swimmers to cyclists and many team sports. Chris works with a lot of youth athletes, highly prioritizing a long term athletic development model.

References

1. Faigenbaum, A. D. (2007). State of the Art Reviews: Resistance Training for Children and Adolescents: Are There Health Outcomes?. American Journal of Lifestyle Medicine1(3), 190-200. 

2. Heinonen, A., Sievänen, H., Kannus, P., Oja, P., Pasanen, M., & Vuori, I. (2000). High-impact exercise and bones of growing girls: a 9-month controlled trial. Osteoporosis international11(12), 1010-1017.

3. Behm, D. G., Faigenbaum, A. D., Falk, B., & Klentrou, P. (2008). Canadian Society for Exercise Physiology position paper: resistance training in children and adolescents. Applied physiology, nutrition, and metabolism33(3), 547-561.

4. Behringer, M., vom Heede, A., Yue, Z., & Mester, J. (2010). Effects of resistance training in children and adolescents: a meta-analysis. Pediatrics126(5), e1199-e1210.

5. Peitz, M., Behringer, M., & Granacher, U. (2018). A systematic review on the effects of resistance and plyometric training on physical fitness in youth-What do comparative studies tell us?. PloS one13(10).

6. Long Term Development in Sport and Activity. https://sportforlife.ca/wp-content/uploads/2019/06/Long-Term-Development-in-Sport-and-Physical-Activity-3.0.pdf

7. Balyi, I., & Way, R. (2005). The role of monitoring growth in long-term athlete development. Can Sport Life, 8-10.

8. Behm, D. G., Young, J. D., Whitten, J. H., Reid, J. C., Quigley, P. J., Low, J., … & Prieske, O. (2017). Effectiveness of traditional strength vs. power training on muscle strength, power and speed with youth: a systematic review and meta-analysis. Frontiers in physiology8, 423.

9. Moran, J., Sandercock, G., Ramirez-Campillo, R., Clark, C. C., Fernandes, J. F., & Drury, B. (2018). A meta-analysis of resistance training in female youth: its effect on muscular strength, and shortcomings in the literature. Sports Medicine48(7), 1661-1671.

10. Faigenbaum, A. D., Kraemer, W. J., Blimkie, C. J., Jeffreys, I., Micheli, L. J., Nitka, M., & Rowland, T. W. (2009). Youth resistance training: updated position statement paper from the national strength and conditioning association. The Journal of Strength & Conditioning Research23, S60-S79.