BoneScience Research Notes · Last reviewed: 2026-10 · General information, not medical advice
- Strength training can be safe for kids and teens when a qualified coach watches every session.
- It clearly makes kids stronger. Longer programs work better than short ones.
- Start light, learn good form, and train 2 to 3 times a week with rest days in between.
The worry many parents have
Lots of parents have heard that lifting weights is bad for growing kids. So what does the research say?
Strength training, also called resistance training, means making muscles work against a load. The load can be body weight, bands, or weights.
Is it safe?
A 2010 review looked at injury reports in young lifters. Injuries have happened. But most were accidents.
The review found three things behind many of them: poor form, loads that were too heavy, and no qualified coach. The authors said strength training can be safe and worthwhile for kids and teens. The condition is that a qualified adult supervises every session and teaches proper lifting.
A Canadian expert group came to a similar view. It said there is no minimum age, as long as the training fits the child.
Does it work?
Yes. A 2010 review in Pediatrics pooled controlled trials of kids and teens under 18. Strength training clearly made them stronger. The average effect was large.
What is an effect size? It is a way to compare results across many studies. Researchers often call 0.2 small, 0.5 medium and 0.8 large. So 1.12 means kids in training programs got clearly stronger than similar kids who did not train.
Older and more mature kids tended to gain more strength. But there was no special boost during puberty. Programs that lasted longer, and that included more sets, worked better.
A 2016 review looked at 43 studies of young athletes aged 6 to 18. Strength training gave moderate gains in strength and jumping. It gave smaller gains in sprinting and agility.
For strength, the best results came from programs that lasted more than 23 weeks. Those were coached programs for athletes, not a plan to copy at home.
What about bones?
Bones respond to load too. Strength training is one way to load them. Running and jumping are another. A 2014 review of 27 studies found that weight-bearing exercise raised bone mineral in kids. The gains were small on average and were bigger before puberty.
What this research says / doesn't say
Says: With a qualified coach and good form, strength training can be safe for kids and teens. It makes them stronger, and longer programs work better. Most injuries in young lifters were accidents linked to poor form, heavy loads or no coaching.
Doesn't say: That lifting at home without a coach is safe. It does not say strength training changes how tall a child will be. The athlete studies used heavy loads under supervision, which is not a starting plan for beginners.
Why form comes first
The 2010 safety review linked many injuries to poor technique and loads that were too heavy. That is why good youth programs teach the movement first. Kids practice with body weight or a light band. Load goes up slowly, and only when form stays clean.
A good coach also plans the week. The Canadian guidance suggests low to moderate effort, 2 to 3 times a week, never on back-to-back days. Each session starts with a warm-up and ends with a cool-down.
How to start
- Find a qualified coach. Look for someone who trains young people and watches every rep.
- Form before weight. Start with body weight or light loads. Add load only when form stays good.
- Two to three days a week. Leave a rest day in between. Begin with 1 to 2 sets per exercise.
- Make it fun. Kids stick with what they enjoy. That matters more than any single workout.
Sources
- Faigenbaum AD, Myer GD. Resistance training among young athletes: safety, efficacy and injury prevention effects. Br J Sports Med. 2010;44(1):56-63. doi:10.1136/bjsm.2009.068098
- Behm DG, Faigenbaum AD, Falk B, Klentrou P. Canadian Society for Exercise Physiology position paper: resistance training in children and adolescents. Appl Physiol Nutr Metab. 2008;33(3):547-561. doi:10.1139/H08-020
- Behringer M, Vom Heede A, Yue Z, Mester J. Effects of resistance training in children and adolescents: a meta-analysis. Pediatrics. 2010;126(5):e1199-e1210. doi:10.1542/peds.2010-0445
- Lesinski M, Prieske O, Granacher U. Effects and dose-response relationships of resistance training on physical performance in youth athletes: a systematic review and meta-analysis. Br J Sports Med. 2016;50(13):781-795. doi:10.1136/bjsports-2015-095497
- Behringer M, Gruetzner S, McCourt M, Mester J. Effects of weight-bearing activities on bone mineral content and density in children and adolescents: a meta-analysis. J Bone Miner Res. 2014;29(2):467-478. doi:10.1002/jbmr.2036
This article is general information, not medical advice. Check with your pediatrician before your child starts a new training program, especially if they have a health condition.
*These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.
BoneScience makes Dr's Grow UP, an AM/PM daily nutrition system for ages 10+, NSF Certified for Sport®.
The studies above were not conducted on BoneScience products.
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