Many parents ask us about Strength or Resistance Training and its impact on children. Today, Jungle Miami' s post touches this very important subject, by publishing the policy and guidelines set by the American Academy Of Pediatrics's Council on Sports Medicine and Fitness (Revised on April, 1st, 2008).
Strength Training by Children and Adolescents
Pediatricians are often asked to give advice on the safety and efficacy of strength training programs for children and adolescents. This review, a revision of a previous American Academy of Pediatrics policy statement, defines relevant terminology and provides current information on risks and benefits of strength training for children and adolescents.
Strength training (also known as resistance training) is a common component of sports and physical fitness programs for young people. Some adolescents and preadolescents may use strength training as a means to enhance muscle size and definition or to simply improve appearance.
Strength training programs may include the use of free weights, weight machines, elastic tubing, or body weight. The amount and form of resistance used as well as the frequency of resistance exercises is determined by specific program goals. Table 1 defines common terms used in strength training.
BENEFITS OF RESISTANCE TRAINING
In addition to the obvious goal of getting stronger, strength training programs may be undertaken to improve sports performance, rehabilitate injuries, prevent injuries, and/or enhance long-term health. Studies have shown that strength training, when properly structured with regard to frequency, mode (type of lifting), intensity, and duration of program, can increase strength in preadolescents and adolescents.1-4 Gains in strength, muscle size, or power are lost after 6 weeks if resistance training is discontinued.5 Maintenance exercises may offset these losses, but specific recommendations for maintaining strength gains have not been defined for preadolescents and adolescents.
In preadolescents, proper resistance training can enhance strength without concomitant muscle hypertrophy. Such gains in strength can be attributed to neuromuscular "learning," in which training increases the number of motor neurons that will fire with each muscle contraction.2,6,7 This mechanism helps explain strength gains from resistance training in populations with low androgen levels, including females and preadolescent males. Strength training can also augment the muscle enlargement that normally occurs with pubertal growth in males and females.3,6,8,9
Strength training can improve an adolescent athlete's performance in weight lifting and power lifting. Strength training is a common practice in sports like football in which size and strength are desirable. Despite theoretical benefits, scientific studies have failed to consistently show that improved strength enhances running speed, jumping ability, or overall sports performance.6,10
Evidence that strength training programs help prevent sports-related musculoskeletal injuries in preadolescents and adolescents is inconclusive.11 Furthermore, there is no evidence that strength training will reduce the incidence of catastrophic sports-related injuries.
RISKS OF STRENGTH TRAINING
The US Consumer Product Safety Commission, through its National Electronic Injury Surveillance System (NEISS), has estimated the number of injuries that are associated with strength training equipment. The NEISS data neither specifies cause of injury nor separates recreational from competitive weight lifting injuries. From 1991 to 1996, an estimated 20 940 to 26 120 injuries occurred each year in individuals under 21 years old.12 According to NEISS data and other studies,13 muscle strains account for 40% to 70% of all injuries. The lumbar back is the most commonly injured area.11,14
A limited number of case reports have raised concern about epiphyseal injuries in the wrist and apophyseal injuries in the spine from weight lifting in skeletally immature individuals. Such injuries are uncommon and are believed to be largely preventable by avoiding improper lifting techniques, maximal lifts, and improperly supervised lifts.12,15,16
Strength training programs do not seem to adversely affect linear growth and do not seem to have any long-term detrimental effect on cardiovascular health.2,417-19 Young athletes with hypertension may experience further elevation of blood pressure from the isometric demands of strength training.8
STRENGTH TRAINING GUIDELINES
A medical evaluation before commencing a formal strength training program can identify possible risk factors for injury and provide an opportunity to discuss training goals, techniques, and expectations. Risks involved with use of anabolic steroids and other body-building supplements are appropriate topics for discussion with any adolescent interested in getting bigger and stronger.20,21
If children or adolescents undertake a strength training program, they should begin with low-resistance exercises until proper technique is learned. When 8 to 15 repetitions can be performed, it is reasonable to add weight in small increments. Exercises should include all muscle groups and be performed through the full range of motion at each joint. To achieve gains in strength, workouts need to be at least 20 to 30 minutes long, take place a minimum of 2 to 3 times per week, and continue to add weight or repetitions as strength improves. There is no additional benefit to strength training more than 4 times per week.5
Young people who want to improve sports performance will generally benefit more from practicing and perfecting skills of the sport than from resistance training. If long-term health benefits are the goal, strength training should be combined with an aerobic training program.
1. Strength training programs for preadolescents and adolescents can be safe and effective if proper resistance training techniques and safety precautions are followed.
2. Preadolescents and adolescents should avoid competitive weight lifting, power lifting, body building, and maximal lifts until they reach physical and skeletal maturity.
3. When pediatricians are asked to recommend or evaluate strength training programs for children and adolescents, the following issues should be considered: a. Before beginning a formal strength training program, a medical evaluation should be performed by a pediatrician. If indicated, a referral may be made to a sports medicine physician who is familiar with various strength training methods as well as risks and benefits in preadolescents and adolescents.
b b. Aerobic conditioning should be coupled with resistance training if general health benefits are the goal.
c c. Strength training programs should include a warm-up and cool-down component.
d d. Specific strength training exercises should be learned initially with no load (resistance). Once the exercise skill has been mastered, incremental loads can be added. e. Progressive resistance exercise requires successful completion of 8 to 15 repetitions in good form before increasing weight or resistance.
f f. A general strengthening program should address all major muscle groups and exercise through the complete range of motion.
g g. Any sign of injury or illness from strength training should be evaluated before continuing the exercise in question.
Committee on Sports Medicine and Fitness, 2000-2001
Reginald L. Washington, MD, Chairperson
David T. Bernhardt, MD
Jorge Gomez, MD
Miriam D. Johnson, MD
Thomas J. Martin, MD
Thomas W. Rowland, MD
Eric Small, MD
Claire LeBlanc, MD
Canadian Pediatric Society
Robert Malina, PhD
Institute for the Study of Youth Sports
Carl Krein, AT, PT
National Athletic Trainers Association
Judith C. Young, PhD
National Association for Sport and Physical Education
Frederick E. Reed, MD
Section on Orthopedics
Steven J. Anderson, MD
Bernard A. Griesemer, MD
Oded Bar-Or, MD
The recommendations in this statement do not indicate an exclusive course of treatment or serve as a standard of medical care. Variations, taking into account individual circumstances, may be appropriate.