Strength Training for Kids and Teens
Written by Nutrition Student Vivien Nereen Saguros
Staying active is a key part of a healthy, well-balanced lifestyle. Exercise can include sports, biking, yoga, or simply playing outside. As children grow into pre-teens and teenagers, they may become interested in resistance exercise also known as strength training. Many kids enjoy it as a hobby, a way to bond with friends, or even competitively.
For many parents, this raises questions: Is it safe? Can it affect growth? How much is too much?
There are many myths about strength training for youth, but when done properly and paired with good nutrition, it can support your child’s growth, health, and confidence. Let’s break down what it is, how to start safely, and how food can fuel their progress.
What is resistance training?
Resistance or strength training uses an external force to work muscles, promoting growth and strength. This can include:
Strength training with body weight or “Calisthenics” (1): Using body weight is the simplest form of strength training in which you use your own body against gravity as resistance to work your muscles. This can all be done in the comfort of your own home. No gym, no equipment, no extra costs!
Strength training with free weights (4): Free weights is just a fancy word for dumbbells, kettle bells, barbells and any sort of weight that isn’t attached to machines and can be moved around.
Strength training with weight machines (7): This form of strength training is the most popular method of strength building as it targets specific muscle groups and uses machines to add extra weights to your child’s workouts. This is different from using free weights because the machines can guide your child’s movements and ensure that proper technique is used to avoid injury.
All these types of strength training can improve muscle growth, endurance, and overall strength. The goal is to build healthy habits, not to “bulk up’ overnight.
Is strength training safe for kids?
You may have heard that strength training can stunt your child’s growth and that only children who are athletes can benefit from this type of exercise. However, these are just myths and research shows that with the proper guidance and supervision, strength training is safe for teenagers and children when done with proper form.
Strength training offers benefits that go beyond enhancing sports performance such as (5):
Promote better bone health and support growth and density, which has long-term effects as your child ages
Improves their mood and overall well-being
Better heart health and lowers risks of chronic disease development
Improves their posture
Maintains a healthy weight
These are long-term benefits that extend into adulthood and promote habits that fit into a healthy lifestyle as they get older.
In the meantime, letting your child or teenager start their fitness journey can improve their performance in gym class and encourage participation in extracurricular activities like sports and after school fitness programs to meet peers with the same interests and goals.
Exercise Recommendations to Get Your Child Started (7)
It can be scary introducing your child to strength training, especially with all of the safety concerns you may have. But here are some tips to get your child started safely and comfortably.
Start with a warmup: Your child might be eager to jump into doing strength training exercises right away, but it is important to get our bodies ready before starting a workout. To do this, your child should aim to stretch and do pre-workout warmups for at least 5 to 10 minutes and it can include movements such as:
Shoulder rolls
Arm Circles
Leg Swings
Side Bends
Hamstring Stretch
Begin with body weight exercises: When your child is new to strength training, it is a good idea to start with body weight exercises to build strength and learn the proper movements or form. This can include doing exercises such as:
Pushups and variations (assisted pushups on knees, wall pushups)
Planks and variations (up-and-down planks, side planks, reverse planks, spider planks)
Pull ups and monkey bars
Sit ups
Tricep dips
Lunges and variations (lateral lunge, curtsy lunge, reverse lunge)
Introduce Weights Slowly: Once your child has mastered the movements, you can start adding weights to their routine. This can include adding dumbbells or ankle weights to their current exercises to make it harder.
To do this, start light! Learning the proper form when you first start using weights is very important to avoid injury
Gradually increase the weight as they gain more confidence and get stronger
Supervise them or have coach or trainer guide them to ensure that they are using the proper technique and have help
Importance of Rest Days: Muscles need time to rest and recover, so limit working out to 3 or 4 days a week with each day focused on a different muscle group! Having days off from the gym will not ruin progress and can allow your child to prepare for their next workout.
In general, a workout with 3 or 4 exercises with 3 sets of 10 repetitions or 4 sets of 8 repetitions per muscle group is enough (7). Consult a health care professional and coach or trainer to
determine a personalized plan or recommendations fit for your child before you start.
Nutrition to Support Your Workout (2)
Nutrition plays a key role in building muscle, fuelling your child’s workout, recovery and overall growth in teenagers and children. To meet their energy needs, your child should have balanced meals throughout the day that include:
Protein - A key nutrient in supporting muscle growth and recovery that you can find in food sources like eggs, legumes (kidney beans, chickpeas and lentils) and tofu
Carbohydrates - This nutrient is our muscle and brain’s main source of energy, and it can be found in food like potatoes, bread, rice and pasta. Not getting enough carbohydrates can make your child feel tired quicker during physical activity.
Fat - Adding healthy fat can help your child meet the higher energy demands of physical activity while supporting growth and everyday activities. This is found in food like avocado, nuts and Greek yogurt.
Water and Hydration- Drinking water is important because your child will lose a lot of water through sweat during their workout. Staying hydrated will keep your child energized and focused.
Pre-Workout and Post-Workout Nutrition (2, 3, 6)
Planning and scheduling meals or snacks is part of building a workout routine as timing can optimize muscle building and recovery and ensure your child has the energy to exercise. When choosing meals and times for your child to eat:
Aim to have meals about 2 to 3 hours before your child’s workout. (0.3 g/kg on average 20 g to 30 g protein plus 1g/kg to 1.5 g/kg carbohydrates)
If not, your child can add in a protein-rich snack an hour before his or her workout. (0.5 g/kg to 1 g/kg carbohydrates plus 0.11 g/kg on average 10 g to 15 g protein)
After your child’s workout, try to have a protein-rich snack within 30 minutes to an hour to optimize muscle growth. (0.5 g/kg to 1 g/kg carbohydrate plus 0.11 g/kg protein)
Meals, ideally 3 to 4 hours following a workout, should also consist of protein combined with carbohydrates (1 g/kg to 1.5 g/kg carbohydrates plus 0.3 g/kg protein)
To help you visualize, a meal-time serving of protein can look like anything from the size of your child’s palm and a serving of carbohydrates can look like anything from the size of your child’s fist. A snack time serving of protein and carbohydrates would be about half of what your child would have during a meal.
Some snack ideas that your child can add to their routine are:
Tuna or chicken breast with a slice of whole wheat bread or multigrain crackers
Carrots and hummus
Apples or bananas with nut butter or a handful of nuts
Greek yogurt with berries
Cottage cheese with their choice of fruit, multigrain crackers, slice of bread
Protein Powder and Supplements - Does Your Child Need it? (2, 3)
A food first approach and eating is encouraged before considering supplement use because adding protein-rich food offers more nutrients that are not found in supplements and makes your child feel full or satisfied. In fact, most children and teenagers can meet their protein needs through a proper diet.
However, supplements such as protein powders, protein bars or shakes may be useful in some cases like older teenagers who engage in high intensity workouts. These should not be used to replace food and if used:
Stick to one serving (about 11 g - 15g protein) before or after workouts
Look for simple, high-quality options without unnecessary additives
Consider protein-fortified foods as alternatives (protein yogurt, protein pasta, fortified milk)
Bottom Line
Strength training can be a safe and rewarding activity for kids and teens, if approached the right way. Encourage them to:
Start slow and master the basics
Make rest and recovery a priority
Fuel their bodies with balanced meals and snacks
View exercise as part of a healthy lifestyle, not just a way to “look stronger”
With your guidance, strength training can boost not only physical health but also confidence, resilience, and lifelong habits.
References
Alves, J. G. B., & Alves, G. V. (2019). Effects of physical activity on children's growth. Jornal de pediatria, 95 Suppl 1, 72–78. https://doi-org.ezproxy.lib.torontomu.ca/10.1016/j.jped.2018.11.003
Capra, M. E., Stanyevic, B., Giudice, A., Monopoli, D., Decarolis, N. M., Esposito, S., & Biasucci, G. (2024). Nutrition for Children and Adolescents Who Practice Sport: A Narrative Review. Nutrients, 16(16), 2803. https://doi-org.ezproxy.lib.torontomu.ca/10.3390/nu16162803
Jäger, R., Kerksick, C. M., Campbell, B. I., Cribb, P. J., Wells, S. D., Skwiat, T. M., Purpura, M., Ziegenfuss, T. N., Ferrando, A. A., Arent, S. M., Smith-Ryan, A. E., Stout, J. R., Arciero, P. J., Ormsbee, M. J., Taylor, L. W., Wilborn, C. D., Kalman, D. S., Kreider, R. B., Willoughby, D. S., Hoffman, J. R., … Antonio, J. (2017). International Society of Sports Nutrition Position Stand: protein and exercise. Journal of the International Society of Sports Nutrition, 14, 20. https://doi-org.ezproxy.lib.torontomu.ca/10.1186/s12970-017-0177-8
McQuilliam, S. J., Clark, D. R., Erskine, R. M., & Brownlee, T. E. (2020). Free-Weight Resistance Training in Youth Athletes: A Narrative Review. Sports medicine (Auckland, N.Z.), 50(9), 1567–1580. https://doi-org.ezproxy.lib.torontomu.ca/10.1007/s40279-020-01307-7
Miao, T., Li, X., Zhang, W., Yang, F., & Wang, X. (2025). Effects of high-impact jumping versus resistance exercise on bone mineral content in children and adolescents: a systematic review and meta-analysis. PeerJ (San Francisco, CA), 13, Article e19616. https://doi.org/10.7717/peerj.19616
Ravindra, P. V., Janhavi, P., Divyashree, S., & Muthukumar, S. P. (2022). Nutritional interventions for improving the endurance performance in athletes. Archives of physiology and biochemistry, 128(4), 851–858. https://doi-org.ezproxy.lib.torontomu.ca/10.1080/13813455.2020.1733025
Stricker, P. R., Faigenbaum, A. D., McCambridge, T. M., & COUNCIL ON SPORTS MEDICINE AND FITNESS (2020). Resistance Training for Children and Adolescents. Pediatrics, 145(6), e20201011. https://doi-org.ezproxy.lib.torontomu.ca/10.1542/peds.2020-1011