T Nation 🔥 Super Kids: The Latest Training & Nutrition Science 🚀

Super Kids: The Latest Training & Nutrition Science

Cy Willson

Strength, Technique, Rep Ranges, and More

Gotta kiddo or two? Here's what the latest research says about lifting weights, protein intake, creatine, and more.

Decades ago, people believed strength training and everything that improve it – getting adequate protein, taking creatine, maxing out, etc. – were reserved for older teens and adults. The consensus was that lifting causes permanent damage to growing adolescent bodies. Those notions are long outdated. Check out the latest research.

Kids and Resistance Training

The American Academy of Pediatrics is on board with resistance training for kids. As long as they're learning proper technique and someone trustworthy is supervising them, the potential benefits are significant:

• Improved body composition
• Strength
• Power
• Speed
• Muscular endurance
• Cardiorespiratory fitness
• Decreased risk of injury (1-3)

Before puberty, however, increases in muscle mass are smaller, and strength gains come primarily from increased motor neuron recruitment. This isn't bad news, though. Learning technique and gaining motor neuron recruitment sets kids up for faster success when they do hit puberty.

But doesn't lifting weights stunt kids' growth? There's zero evidence. On the contrary, resistance training may promote bone development (1-3). There's also no evidence that well-trained and supervised kids are any more likely to be injured in the weight room than playing out at recess.

Sure, without proper training, a kid risks injuries, especially with Olympic-style weightlifting where more complicated lifts require better technique. If you're not comfortable training and supervising your kid, hire an experienced coach to give them a good foundation (after a doctor has cleared your kid to participate).

• Technique – Research indicates that learning proper technique is paramount in reducing the risk of injury (1-3). That is common sense, but because some kids want to push themselves early, so it's important to supervise them closely. Kids may find flawless form boring, but that's why they have adults around to guide them. If using a barbell isn't feasible, starting with PVC or broomstick is useful for getting the basic movements down.


• Age – It varies, but getting your kid to start weight training as early as age 7 (1-3) isn't unreasonable. Even those as young as 4 to 5 can begin bodyweight exercises.


• Frequency – Two or three days per week is a good starting point.


• Rep Ranges – Younger kids do well with a rep range of 10-15 at or less than 60% of their max. Do it while reinforcing strict form. As they progress and get stronger, they can use shorter periods of heavier weights in the 6-12 rep range at or less than 80% of their 1 RM. And after continued progress, they can eventually work in the 4-6 rep range at above 80% of their 1 RM.


• Maxing Out – Maxing out or determining a 1 RM was previously discouraged for fear of injury (1, 2). However, it has more recently become acceptable, provided they have proper technique and are monitored along with the usual warm-up and stretching. Obviously, this is where close supervision is needed to prevent Billy's squats from devolving into good mornings. Once your kid's form begins to deteriorate, or if he experiences pain, it's time to back off or quit for the day.

Kids, Protein Intake, and Other Stuff

Active kids need sufficient protein, not just for their gym activities but for normal growth and development. Health experts recommend 0.9 to 0.95 g/kg/bodyweight/day to meet basic needs (4,5). However, an optimal intake for kids may in fact be around 1.6 grams per kg of body weight per day (6-8).

This isn't difficult if you spread it out over several meals. For example, even 10 pieces of nuggets provide 23 grams of protein. My son, for example, weighs around 110 pounds or 50 kilograms, which requires 80 grams daily. If his typical meal contains around 15-20 grams of protein and he eats 4-5 times daily, this makes hitting that recommendation pretty easy.

Obviously, giving kids protein supplements isn't necessary if they have a decent appetite for protein-rich foods like milk, yogurt, cheese, and meat.

Creatine

My son has been begging me to let him use creatine monohydrate for years, but reserve that for kids until they have at least reached high school age, around age 14 or 15.

The International Society of Sports Nutrition concluded that creatine supplementation is likely safe for children and adolescents and potentially beneficial. Although the studies were smaller in size, safety was not a primary variable examined (9-11).

Other authors have taken a more cautious approach and called for more research, especially studying the long-term effects of supplementation in children and adolescents (12). For most healthy teenagers, supplementing with creatine – under their parents' supervision and consent from their physician – is likely fine for periods of intense resistance training.

Caffeine and Energy Drinks

If your kid doesn't consume much, if any, caffeine, there's no reason for them to start. I've seen a lot of kids consume far too much from various sources and it can be dangerous since it's not an innocuous substance.

While there's no consensus on safe caffeine intake for children and adolescents, researchers have proposed 2.5 mg per kg to 3 mg per kg as potential limits, albeit based on limited data (13-16). A total limit of 100 mg/day for those ages 12-17 has also been proposed (14).

This is considering caffeine alone and doesn't consider how other ingredients might interact with it. For example, researchers recently found that children who were administered 3 mg per kg of caffeine (a dose not expected to cause serious issues) experienced increased supraventricular extrasystoles (premature beats). The authors argue that ongoing use could make them more predisposed to cardiac arrhythmias (17).

While the seriousness of such an effect could be debated, it does concern me, particularly for kids who may have pre-existing cardiovascular conditions (many of which are probably undiagnosed) and may already be predisposed to cardiac arrhythmias. Along these same lines, there's some evidence that ingredients such as taurine, combined with caffeine, may have divergent effects compared to caffeine alone (18).

The recommendations for caffeine intake based on age groups also vary, with some indicating that no caffeine should be consumed until age 12, while others have indicated that it's best to wait until age 14. Nonetheless, I've yet to see any well-based argument as to why an 11-year-old couldn't consume at or less than 2.5 mg per kg of body weight per day while a 12 or a 13-year-old could, other than perhaps a larger body weight.

Regarding caffeine metabolism, available studies indicate that up until age 15, CYP1A2-mediated clearance in children is greater than in adults. In fact, CYP1A2-mediated clearance is on par with adults as soon as age 3 and begins to exceed that of adults from age 3 to around age 15.

It's generally not until early puberty (girls) or late puberty (boys) that caffeine metabolism declines to once again parallel that of adults (19). That's not to say that children and adolescents are simply miniature adults; they could be more sensitive than adults physiologically for some variables (20). However, I don't see the rationale for parsing age groups this way.

So educate your kid on the potential danger of consuming too much caffeine. Avoid buying them energy drinks in particular, especially those containing both caffeine and taurine. If they do enjoy something like coffee or caffeinated soda, limit them to no more than 2.5 mg per kg or 100 mg of total caffeine per day, whichever is less, although even this dose can cause some anxiety and irritability in some.

Take-Home Points

• Lifting is good for kids and helps them perform better in sports, but learning and exhibiting proper technique under supervision is key.


• Around .72 grams of protein per pound of body weight is optimal for active kids.


• While creatine monohydrate is probably safe for kids, have them wait until high school before trying it out.


• Kids should avoid caffeine until age 12 to 14. A maximum dose of 2.5 mg/kg/day or 100 mg per day (whichever is less) is likely ok for kids this age or older. But this amount doesn't take into account other ingredients that may potentiate the effects of caffeine or cause different effects on cardiovascular variables.

References

1. Pierce KC, Hornsby WG, Stone MH. Weightlifting for Children and Adolescents: A Narrative Review. Sports Health. 2022 Jan-Feb;14(1):45-56. doi: 10.1177/19417381211056094. Epub 2021 Nov 15. PMID: 34781771; PMCID: PMC8669931.
2. Stricker PR, Faigenbaum AD, McCambridge TM; Council on Sports Medicine and Fitness. Resistance Training for Children and Adolescents. Pediatrics. 2020 Jun;145(6):e20201011. doi: 10.1542/peds.2020-1011. PMID: 32457216.
3. Woods B. Youth Weightlifting-A Review on The Risks, Benefits, And Long-Term Athlete Development Associated with Weightlifting Amongst Youth Athletes. Journal of Australian Strength and Conditioning. 2019;27(3):53-68.
4. Richter M, Baerlocher K, Bauer JM, Elmadfa I, Heseker H, Leschik-Bonnet E, Stangl G, Volkert D, Stehle P; on behalf of the German Nutrition Society (DGE). Revised Reference Values for the Intake of Protein. Ann Nutr Metab. 2019;74(3):242-250. doi: 10.1159/000499374. Epub 2019 Mar 22. PMID: 30904906; PMCID: PMC6492513.
5. Burd NA, McKenna CF, Salvador AF, Paulussen KJM, Moore DR. Dietary Protein Quantity, Quality, and Exercise Are Key to Healthy Living: A Muscle-Centric Perspective Across the Lifespan. Front Nutr. 2019 Jun 6;6:83. doi: 10.3389/fnut.2019.00083. PMID: 31245378; PMCID: PMC6563776.
6. Desbrow B. Youth Athlete Development and Nutrition. Sports Med. 2021 Sep;51(Suppl 1):3-12. doi: 10.1007/s40279-021-01534-6. Epub 2021 Sep 13. PMID: 34515968; PMCID: PMC8566439.
7. Moore DR. Protein Metabolism in Active Youth: Not Just Little Adults. Exerc Sport Sci Rev. 2019 Jan;47(1):29-36. doi: 10.1249/JES.0000000000000170. PMID: 30334848.
8. Elango R, Humayun MA, Ball RO, Pencharz PB. Protein requirement of healthy school-age children determined by the indicator amino acid oxidation method. Am J Clin Nutr. 2011 Dec;94(6):1545-52. doi: 10.3945/ajcn.111.012815. Epub 2011 Nov 2. PMID: 22049165.
9. Jagim AR, Kerksick CM. Creatine Supplementation in Children and Adolescents. Nutrients. 2021 Feb 18;13(2):664. doi: 10.3390/nu13020664. PMID: 33670822; PMCID: PMC7922146.
10. Kreider RB, Kalman DS, Antonio J, Ziegenfuss TN, Wildman R, Collins R, Candow DG, Kleiner SM, Almada AL, Lopez HL. International Society of Sports Nutrition position stand: safety and efficacy of creatine supplementation in exercise, sport, and medicine. J Int Soc Sports Nutr. 2017 Jun 13;14:18. doi: 1186/s12970-017-0173-z. PMID: 28615996; PMCID: PMC5469049.
11. Antonio J, Candow DG, Forbes SC, Gualano B, Jagim AR, Kreider RB, Rawson ES, Smith-Ryan AE, VanDusseldorp TA, Willoughby DS, Ziegenfuss TN. Common questions and misconceptions about creatine supplementation: what does the scientific evidence really show? J Int Soc Sports Nutr. 2021 Feb 8;18(1):13. doi: 10.1186/s12970-021-00412-w. PMID: 33557850; PMCID: PMC7871530.
12. Metzger GA, Minneci PM, Gehred A, Day A, Klingele KE. Creatine supplementation in the pediatric and adolescent athlete-- A literature review. J Orthop. 2023 Mar 25;38:73-78. doi: 10.1016/j.jor.2023.03.010. PMID: 37008451; PMCID: PMC10063391.
13. Verster JC, Koenig J. Caffeine intake and its sources: A review of national representative studies. Crit Rev Food Sci Nutr. 2018 May 24;58(8):1250-1259. doi: 10.1080/10408398.2016.1247252. Epub 2017 Jun 12. PMID: 28605236.
14. Seifert SM, Schaechter JL, Hershorin ER, Lipshultz SE. Health effects of energy drinks on children, adolescents, and young adults. Pediatrics. 2011 Mar;127(3):511-28. doi: 10.1542/peds.2009-3592. Epub 2011 Feb 14. Erratum in: Pediatrics. 2016 May;137(5):null. PMID: 21321035; PMCID: PMC3065144.
15. Nawrot P, Jordan S, Eastwood J, Rotstein J, Hugenholtz A, Feeley M. Effects of caffeine on human health. Food Addit Contam. 2003 Jan;20(1):1-30. doi: 10.1080/0265203021000007840. PMID: 12519715.
16. EFSA Panel on Dietetic Products, Nutrition and Allergies (NDA). Scientific Opinion on the safety of caffeine. EFSA Journal. 2015 May;13(5):4102.
17. Mandilaras G, Li P, Dalla-Pozza R, Haas NA, Oberhoffer FS. Energy Drinks and Their Acute Effects on Heart Rhythm and Electrocardiographic Time Intervals in Healthy Children and Teenagers: A Randomized Trial. Cells. 2022 Jan 31;11(3):498. doi: 10.3390/cells11030498. PMID: 35159306; PMCID: PMC8834195.
18. Fletcher EA, Lacey CS, Aaron M, Kolasa M, Occiano A, Shah SA. Randomized Controlled Trial of High-Volume Energy Drink Versus Caffeine Consumption on ECG and Hemodynamic Parameters. J Am Heart Assoc. 2017 Apr 26;6(5):e004448. doi: 10.1161/JAHA.116.004448. PMID: 28446495; PMCID: PMC5524057.
19. Willson C. The clinical toxicology of caffeine: A review and case study. Toxicol Rep. 2018 Nov 3;5:1140-1152. doi: 10.1016/j.toxrep.2018.11.002. PMID: 30505695; PMCID: PMC6247400.
20. Turley KR, Desisso T, Gerst JW. Effects of caffeine on physiological responses to exercise: boys versus men. Pediatr Exerc Sci. 2007 Nov;19(4):481-92. doi: 10.1123/pes.19.4.481. PMID: 18089905.