Strength Training for Children: A Review of Research Literature

Two of the most frequently asked questions about children and strength training are "Is it safe for kids to lift weights?" And "At what age can kids start lifting weights?" The sad truth is, many doubts surround the safety and validity of weight training for children. Many would even have you believe that kids have no place at all in the weight room. Despite this conservatism, exercise physiologists and the American Academy of Pediatrics both support the implementation of strength and resistance training programs for young children.

Is it safe for kids to lift weights?

The answer from today's top research authorities is a resounding "yes." Studies show that a moderate intensity strength training program can help increase strength, decrease the risks of injury while playing sports, and increase bone density in children. Exercise physiologists aren't the only ones recommending resistance training; the American Academy of Pediatrics has also put forth a pro-strength training for children statement.

The American Academy of Pediatrics position on strength training supports the implementation of strength and resistance training programs, even for prepubescent children, that are monitored by well-trained adults and take into account the child's maturation level. The only limitation the AAP suggests is to avoid repetitive maximal lifts (lifts that are one repetition maximum lifts or are within 2-3 repetitions of a one repetition maximum lift) until they have reached Tanner Stage 5 of developmental maturity. Tanner Stage 5 is the level in which visible secondary sex characteristics have been developed. Usually, in this stage adolescents will also have passed their period of maximal velocity of height growth

The AAP's concern that children wait until this stage to perform maximal lifts is that the epiphyses, commonly called "growth plates", are still very vulnerable to injury before this developmental stage. It is repeated injury to these growth plates that may hinder growth. For this same reason, two of the leading researchers in the field of youth fitness, Fleck and Kraemer, agree that maximal lifts should be avoided. (2) However, Fleck, Kraemer and the AAP agree that a strength training program that doesn't include maximal lifting is beneficial for prepubescent and pubescent youth. In fact, a strength and resistance training program should be required in certain instances. Let's take a moment to review some of the research:

• "If appropriate training guidelines are followed, regular participation in a youth strength-training program has the potential to increase bone mineral density, improve motor performance skills, enhance sports performance, and better prepare young athletes for the demands of practice and competition." (3)

• A study of young male powerlifters found that high-intensity resistance training is effective in increasing lumbar spine and whole body bone mineral density. (7)

• Resistance training enhances strength and muscular endurance in youth and children. (6) In pre-pubescent children, this increase in strength appears to be the result of neuromuscular activation and coordination supporting evidence that androgens (the hormones largely responsible for increased strength and muscle mass) are not needed for strength gain.(4)

• With proper supervision, children and youth who participate in a strength training program are not at an increased risk for injury compared to children and youth who do not participate in such a program.(4)

These few examples also make a strong statement that a strength and conditioning program reduces the possibility of injuries in children by increasing bone mass. In fact, proper resistance training is incredibly effective at stimulating growth and development, not a hindrance to it! (2)

Young Females and Strength Training

Strength training is particularly important for young girls, as females are at an increased risk for osteoporosis, a degenerative bone disease. There have been several studies that suggest other forms of training, such as plyometric jump training and high impact aerobics, can also increase bone mass in young females. (5, 8) Whichever type of training, it can be especially beneficial when begun prior to puberty. Greater gains in bone mass can be made in premenarchal girls than in those who have already started menstruating. (5)

At what age can kids start lifting weights?

Neither the AAP or exercise physiologists have a minimum age set for a child to begin a resistance training program. Research has been done on moderate weight training programs with children as young as 8 years. However, researchers also recognize the use of calisthenic-type exercises such as push-ups and sit-ups that are commonly used in elementary school physical education classes. Body-weight resistance exercises are a good starting point for most children under the age of 8 or those at any age who are just starting a strength training program. (2) The object of this type of program is to introduce the body to the stresses of training and to teach basic technique.

After a foundation is established, light weight training can be introduced. Fleck and Kraemer recommend a training scheme of 10-15 repetitions and 1-3 sets per muscle group. The weight should be one that the child can lift for 10-15 repetitions without going to muscular failure.

Once a base has been established, the amount of exercises and the weight lifted can be increased. When a child has reached puberty (around age 13 for girls and 15 for boys) and a training foundation has been established, a more advanced periodized routine can be incorporated.

Tips for Supervising a Youth Strength and Resistance Training Program

Safety should always come first when training a youth or child. Before you begin training anyone under the age of 18, be sure to have written parental and medical permission to do so. Make sure the equipment you will be using is free from defects. It is vitally important that young clients are adequately hydrated and sufficiently warmed-up before beginning a training session. A few other important guidelines to follow are:

• youth and children should always be under the direct supervision of a competent trainer or coach when weight training

• first establish the concept of a training program that emphasizes technique and form, not amount of weight used

• teach positive lifestyle habits

• allow only gradual increases in volume and intensity

• move into entry-level adult programs and/or sport specific training only after background knowledge of training has been established and basic technique has been mastered

• employ a wide variety of exercises and training styles to keep interest levels high

• encourage participation in a wide variety of sports and activities

Following these basic guidelines will help develop safe and effective programs for young children and adolescents. Of course, there are many other aspects of training children that cannot be overlooked, but are beyond the scope of this article. The ISSA's Youth Fitness Trainer Course covers topics such assessing a child's maturity level, nutrition, and developing a basic strength training program.

References

1. American Academy of Pediatrics Policy Statement. Strength, Weight and Power Lifting, and Body Building by Children and Adolescents. Pediatrics. 1990; 5: 801-803.

2. Fleck, S.J., Kraemer, W. J. Strength Training for Young Athletes. Champaign, IL: Human Kinetics, 1993.

3. Faigenbaum, A.D. Strength training for children and adolescents. Clinical Sports Medicine. 2000; 4: 593-619.

4. Guy, J.A., Micheli, L.J. Strength training for children and adolescents. Journal of the American Academy of Orthopedic Surgeons. 2000; 1: 29-36.

5. Heinonen, A., Sievanen, H., Kannus, P., Oja, P., Pasanen, M., Vuori, I. High-impact exercise and bones of growing girls: a 9-month controlled trial. Osteoporosis International. 2000; 12: 1010-1017.

6. Payne, V.G., Morrow, J.R., Johnson, L., and Dalton, S.N. Resistance training in children and youth: a meta-analysis. Research Quarterly for Exercise and Sport. 1997; 1: 80-88.

7. Tsuzuku, S., Ikegami, Y., and Yabe, K. Effects of high-intensity resistance training on bone mineral density in young male powerlifters. Calcified Tissue International. 1998; 4: 283-286.

8. Witzke, K.A., Snow, C.M. Effects of plyometric jump training on bone mass in adolescent girls. Medical Science and Sports Exercise. 2000; 6: 1051-1057.