ORLANDO, FLA. — “When will Suzie be old enough to lift weights?” Family physicians may have heard this question from eager parents.
It's important to remind parents that strength is only one aspect of a young athlete's performance, David Bernhardt, M.D., said at a meeting sponsored by the American Academy of Pediatrics.
“Our job is to keep kids active, but excessive weight lifting does not necessarily equal athletic success,” said Dr. Bernhardt, a pediatrics and sports medicine specialist at the University of Wisconsin, Madison. That said, there is no need to discourage children from sensible, moderate strength training, but children should be discouraged from power weight lifting and aesthetic body building, which are not appropriate activities for skeletally immature athletes.
Strength-training exercises using one's own body weight, such as push-ups and sit-ups, and free weights (including small dumbbells, stretching bands, and fitness balls), are better than using weight machines, which are not sized for children, Dr. Bernhardt said.
Safe and effective strength training starts with the proper technique. Children need to learn the techniques of a strength exercise with little or no resistance before adding weight gradually, and they should be able to complete 8–15 repetitions easily, using proper form, before increasing the weight.
Remind them to work all the muscle groups, not just the muscles they see in the mirror.
The question of whether strength training will truly improve performance is difficult to prove, he added. Gains between 30% and 40% have been observed in previous studies, and a 1996 metaanalysis showed that the percentage gains are similar to those in skeletally mature athletes (Sports Med. 1996;22:176–86).
“But, you are looking at smaller quantitative amounts,” Dr. Bernhardt cautioned. In addition, a child's strength naturally increases as he or she grows, which may mask any effects from a specific strength-training program.
“There's a myth out there that strength gains aren't possible without pubertal hormones, and therefore kids who are prepubertal shouldn't be participating in a strength-training program,” Dr. Bernhardt said.
However, short study durations, small numbers, mixed pubertal stages, and lack of controls can confound research in this area.
“The reality is that children can gain significant strength with little risk of injury, but they do need appropriate supervision and technique,” Dr. Bernhardt said.
For example, he cited one study of nine boys and nine girls aged 10–11 years who participated in a 30-minute resistance-training program, three times per week for 9 weeks. The program consisted of three sets of 10 repetitions of various exercises, including thigh presses, chest presses, and back rows. The children demonstrated a mean 30% increase in strength compared with controls. Other equally important outcomes were that the children maintained their baseline flexibility, and no injuries were reported during the 9-week period, Dr. Bernhardt noted.
When a child expresses an interest in strength training, consider the child's motivation, goals, maturity, and whether the strength training would be supervised, he added. The most common reasons for injuries include inadequate coaching, weight training at home, use of free weights without spotters, and inexperience.
The most often-reported strength-training injuries in children are lower back strains. Remind children and parents that although the effect of strength training on body size and composition is difficult to measure while children are growing, there is no evidence that weight training has any detrimental effect on linear growth.
When children and teens ask about strength training, “you should use this as a jumping off point for anticipatory guidance,” Dr. Bernhardt said. Ask what else they are doing to improve their strength. Ask them about nutritional supplements, and talk to them about steroids. Question them about their reasons for wanting to do strength training. Serious overuse injuries to the arms and shoulders due to strength training are more common in older adolescents than in young children. If a child or teenager is lifting enough weight to rupture a biceps or pectoralis muscle, investigate the possibility of steroid use.
Strength training likely has some benefit on overall sports performance, simply because someone who is stronger may be faster or more agile on the athletic field, but such benefits are difficult to prove, and whether increased strength will directly improve flexibility or stamina remains impossible to say, Dr. Bernhardt noted.
However, consider introducing children and parents to the concept of “functional fitness,” which means training the body to move three-dimensionally, as it does in sports, rather than the two-dimensional motions of traditional weight lifting.
For example, suggest that a child do lunges forward, backward, and to the side, rather than forward only. Such triplanar activity, which young children engage in naturally while climbing on monkey bars, for example, can be lost when children become narrowly focused on one sport. Also, consider the sport. If you put a cross-country runner on a heavy muscle-building program, you may not do him or her any favors.