Weight training, also known as resistance training, can have positive benefits for adolescents as well as for adults. Weight training can enhance sports performance and reduce the risk of injury by way of improved strength, enhanced muscular development, refined coordination and motor skills, and better overall fitness. Resistance training in the preadolescent child, however, has been a controversial subject. It is not clear whether the strength gains are significant enough to outweigh the risk of injury. Studies show that before puberty children are capable of strength gains without significant injury or harmful effects on growth and development,^1,2 although, more often, they show greater strength gains during puberty.

When to begin
Children who are less than 12 years old or are prepubescent (before puberty) are considered preadolescent, and teenagers who are roughly 12 to 19 years old are considered adolescents. Although strength gains in preadolescent children have been noted, much of the improvement comes from neurogenic adaptation (recruitment or adaptation of muscle fibers) rather than from an increase in lean muscle mass. Preadolescent children lack androgens, which are natural steroid hormones, such as testosterone or androsterone, that control the development and maintenance of masculine characteristics. The onset of secondary sexual characteristics (pubic and facial hair, enlarged genitalia, etc.) generally predicts the presence of these hormones. The point at which puberty begins varies between the sexes and among individuals. For the most part, children will benefit from a resistance training program after they have reached 13 or 14 years of age when their nervous system and muscle development are sufficient.

How much is too much?
Children who lift weights must be monitored closely. The regimen must be very carefully supervised with emphasis on correct form and not on maximum weight or number of lifts. Resistance should not be increased until the child has learned the proper form and technique for each exercise. Additionally, a young athlete should adhere to some general principles during a training program. The American Orthopaedic Society for Sports Medicine recommends 2 or 3 training sessions per week. The program should include 20 to 30 minutes of training with warm-up and cool-down periods of stretching exercises.³ Olympic-style and competitive weightlifting are very dangerous for any age group and should be avoided entirely in the prepubescent and adolescent age groups.^3-5 Olympic lifting movements, such as the power clean, "snatch," and clean-and-jerk, are associated with low back injuries and spinal defects such as spondylolysis and spondylolisthesis and are not appropriate for these age groups.³

The child should begin with weight resistance that allows 3 sets of 6 to 15 repetitions. Once a child can perform 3 sets of 15 repetitions with appropriate technique and good control, the weight can be increased slowly. Repeat the process each time the child can successfully complete 3 sets of 15 repetitions at a new weight level.

Although preadolescent children have the potential to make modest strength gains, resistance training should ideally begin in adolescence. A progressive program that is closely supervised will help young athletes achieve their strength goals. Following these simple guidelines can help reduce the risk of injury and enhance the benefits of resistance training for the young athlete.

Jay Bradley, MD
Columbus, Georgia

References

1. Sewall L, Micheli LJ. Strength training for children. J Pediatr Orthop. 1986;6:143-146.
2. Rians CB, Weltman A, Cahill BR, Janney CA, et al. Strength training for prepubescent males: is it safe? Am J Sports Med. 1987;15:483-489.
3. Grana WA. Strength training. In: Pediatric and Adolescent Sports Medicine. Vol 3. Philadelphia, Pa: WB Saunders Co; 1994:520-525.
4. Jesse JP. Olympic lifting movements endanger adolescents. Phys Sports Med. 1977:5(9);61-67.
5. Bosco C, Colli R, Introini E, Cardinale M, Tsarpela O, Madella A, Tihanyi J, Viru A. Adaptive responses of human skeletal muscle to vibration exposure. Clin Physiol. 1999;19:183-187.