Increasing numbers of Americans, including children, are turning to the weight room and strength training in their pursuit of fitness. The scarcity of scientific information on strength training for children has raised a number of concerns for coaches, trainers, and parents.

STRENGTH TRAINING & STRENGTH GAINS
Some early scientific studies indicated that strength training was not effective for children prior to puberty. However, more recent experiments clearly indicate that strength-training programs can help increase strength in boys and girls, regardless of age.

STRENGTH TRAINING, BODY SIZE & COMPOSITION
Few scientific studies are available on the effects of strength training on body size and composition in boys and girls. The strength-training programs have generally resulted in small changes in body weight and fatness and have had no influence on height.

It appears that short-term (e.g., 20 weeks) strength-training programs have very little influence on body size and composition during early childhood, especially before adolescence. Whether long-term training will more significantly impact body size and composition remains to be determined.

Only a few studies have investigated the issue of strength training and muscle hypertrophy (increase in muscle size). Such training prior to and during early puberty does not appear to cause muscle hypertrophy in boys or girls.

By contrast, several studies have indicated that such training during adolescence produces significant increases in both arm and leg girths in boys ­ implying a muscle hypertrophy effect of training. There is no information on the effects of strength training of muscle hypertrophy in adolescent girls.

STRENGTH TRAINING & PERFORMANCE
Many of the sports in which children participate demand considerable strength and power, and performance in these sports might be improved with strength training. From a logical perspective, performance could be improved through either the strength gains, changes in body size and composition, or the preventative and rehabilitative outcomes of strength training.

Unfortunately, there is no scientific proof that strength training directly causes improvement in sports performance during childhood. There is some evidence, however, that strength training may contribute to enhanced performance by reducing injury rates for contact sports and by reducing recovery time from injury.

STRENGTH TRAINING & SAFETY
Much of the concern for safety in strength training involves the potential damage to either the growth plates of long bones or toe joints and soft tissues. Such damage could cause stunted growth, acute or chronic pain, impaired motor function, and perhaps disfiguration. However, research suggests that well-supervised strength- training programs can minimize the risk of injury to growth plates, joints, and soft tissue.

STRENGTH TRAINING GUIDELINES FOR CHILDREN AND ADOLESCENTS

Undergo physical and medical check-ups before training
Use strength training as only one of a variety of sport and fitness activities
Use calisthenics to initially build muscle endurance and strength
Use a variety of training methods: calisthenics, free weights, machines
Always develop proper technique first, with low resistance
Progress from low resistance and high repetitions to higher resistance and fewer repetitions
Exercise muscles through their full range of motion
Restrict strength training exercise to three times a week
Use a circuit system approach to maximize cardiovascular fitness
Avoid emphasis on negative or eccentric exercise (e.g., lowering heavy weights)
Include warm-up before training and flexibility exercises after training
rovide constant and experienced adult supervision
Heed pain as a warning, and seek medical advice
Suggested reading on this subject:

Blimkie, C.J.R. Resistance Training During Preadolescence. Issues and Controversies. Sports Medicine 15 (6): 389-407, 1993.