It is important that our youth—children and adolescents—be exposed to a variety of activities that enhance all the components of physical fitness. One key fitness component is the development of muscular strength and endurance. Thus, youth participation in a well-supervised resistance training program becomes crucial in order to meet such a goal. For the purpose of this article, the term “children” will refer to pre-adolescent boys and girls (up to approximately the age of 12) and the term “adolescent” will include boys and girls between 13 and 18 years of age. The term “youth” will include both children and adolescents.
The Benefits of Resistance Training
Research studies strongly suggest that resistance training for youth brings positive benefits. It has been found that most children who adhere to a well-supervised, progressive resistance training program can safely increase their strength and improve their athletic performance. In a meta-analysis of 28 studies on the effectiveness of resistance training in children, Falk & Tenenbaum reported strength gains ranging from 13 to 30 percent. (1) The authors also reported that a training frequency of twice per week was sufficient to induce strength gains; however, the exact duration and intensity remained to be determined. In addition, resistance training may provide some resistance to injury. (2) Stronger, less easily fatigued muscles are less likely to become injured.
Other potential benefits of resistance training for youth may include increases in muscle power, endurance, bone mineral density, body composition, motor performance skills, sports performance, and overall health and well-being.
Mechanisms of Muscular Strength Gains
Prepubescent children gain strength differently than adults. Prior to puberty, motor learning, rather than muscle hypertrophy, is more likely to account for strength increases. (3-7) It appears that muscle-strength gains in children have stemmed from neural adaptations, including changes in motor-unit activation, motor-unit coordination, recruitment, and firing, as opposed to growth in muscle size (hypertrophy).
Moreover, girls and boys achieve similar gains; however, after puberty, boys tend to gain more strength due to testosterone. Furthermore, girls usually experience their fastest increase in muscle strength during their year of most rapid growth, usually about ages of 11.5 to 12.5 years. On the other hand, boys gain muscle strength after their growth spurt, or ages 14.5 to 15.5 years. In addition, training-induced strength gains in boys have been associated with an increase in fat-free mass due to hormonal influences (i.e., testosterone).
Possible Risks and Concerns
Despite the benefits of resistance-training programs, the potential for injuries does exist for children who participate in them. The most common of these are strains, especially to the lumbar spine. Other concerns have focused on the effects of resistance training on growth and bone maturation. Although injuries to the epiphyseal plate (growth cartilage) have been reported in the past among adolescents involved in resistance-training programs, (8,9) such injuries were due to improper technique and training protocols. Faigenbaum and co-workers, however, indicated that resistance training did not have an adverse effect on growth. (10,11) In fact, resistance training may provide an effective stimulus for growth and bone mineralization in children, especially for those at risk for osteopenia, the presence of less than normal amounts of bone, or osteoporosis, loss of bone tissue resulting in bones that are brittle and liable to fracture.
Thus, most experts would agree that children can undertake a well-supervised resistance training program without incurring any further injuries. (1,5-7,12) As long as the training programs are well supervised and taught with age-specific needs in mind, the risk for injuries among children and adolescents becomes very minimal. (13)
The consensus among most experts is that in the initial adaptation period of training, children/adolescents should begin with a training protocol featuring high repetitions (i.e., 1 set of 10-15 reps) and light to moderate loads, at a minimum of twice per week on nonconsecutive days. (13-15) Exercise selection should include all major muscle groups, with a focus on proper technique and execution.
As youngsters progress through the training regimen, it is important to gradually increase their overall exercise volume (i.e. resistance, repetitions, and load). On average, a 5-10 percent increase in training load (i.e., 2 to 5 lbs.) is appropriate for most exercises. Eventually, they can progress to 2-3 sets of 6-15 repetitions, depending upon needs and goals. (13)
It is crucial that children be exposed to a variety of activities that will enhance all the components of physical fitness, including cardiovascular fitness, muscular strength and endurance, body composition, and flexibility. Resistance training becomes, then, an important tool for the development of muscular strength and endurance. When properly instructed, it can be safe, effective and, most importantly, fun!
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(2) American College of Sports Medicine (ACSM). The prevention of sports injuries of children and adolescents. Med Sci Sports Exer 1999;25(8 supplement):1-7.
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(13) President’s Council on Physical Fitness and Sports. Youth resistance training. Res Digest 2003;4(3):1-8.
(14) Faigenbaum A, Loud R, O’Connell J, et al. Effects of different resistance training protocols on upper-body strength and endurance development in children. J Stren Cond Res 2001;15(4):459-465.
(15) Faigenbaum A, Milliken L, Loud R, et al. Comparison of 1 and 2 days per week of strength training in children.