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Strength Training by Children and Adolescents -- Council on Sports Medicine and Fitness 121 (4): 835 -- Pediatrics
POLICY STATEMENT
Strength Training by Children and Adolescents
Council on Sports Medicine and Fitness
Pediatricians are often asked to give advice on the safety and efficacy of strength-training programs for children and adolescents. This statement, which is 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.
BENEFITS OF STRENGTH TRAINING
In addition to the obvious goal of getting stronger, strength-training programs may be undertaken to try to improve sports performance and prevent injuries, rehabilitate injuries, and/or enhance long-term health. Similar to other physical activity, strength training has been shown to have a beneficial effect on several measurable health indices, such as cardiovascular fitness, body composition, bone mineral density, blood lipid profiles, and mental health.1,2 Recent studies have shown some benefit to increased strength, overall function, and mental well-being in children with cerebral palsy.3,4 Resistance training is being incorporated into weight-control programs for overweight children as an activity to increase the ****bolic rate without high impact. Similar to the geriatric population, strength training in youth may stimulate bone mineralization and have a positive effect on bone density.5,6
Multiple studies have shown that strength training, with proper technique and strict supervision, can increase strength in preadolescents and adolescents.7,8 Frequency, mode (type of resistance), intensity, and duration all contribute to a properly structured program. Increases in strength occur with virtually all modes of strength training of at least 8 weeks' duration and can occur with training as little as once a week, although training twice a week may be more beneficial.7–12 Appropriately supervised programs emphasizing strengthening of the core (focusing on the trunk muscles, eg, the abdominal, low back, and gluteal muscles) are also appropriate for children and theoretically benefit sports-specific skill acquisition and postural control. Unfortunately, gains in strength, muscle size, or power are lost 6 weeks after resistance training is discontinued.1,13
In preadolescents, proper resistance training can enhance strength without concomitant muscle hypertrophy. Such gains in strength can be attributed to a neurologic mechanism whereby training increases the number of motor neurons that are "recruited" to fire with each muscle contraction.11,14–16 This mechanism accounts for the increase in strength in populations with low androgen concentrations, including female individuals and preadolescent boys. In contrast, strength training augments the muscle growth that normally occurs with puberty in boys and girls by actual muscle hypertrophy.12,14,17,18
Strength training is a common practice in sports in which size and strength are desirable. Unfortunately, results are inconsistent regarding the translation of increased strength to enhanced youth athletic performance.1,14,19,20 Preventive exercise (prehabilitation) refers to strength-training programs that address areas commonly subjected to overuse injuries, such as providing rotator cuff and scapular stabilization exercises preventively to reduce overuse injuries of the shoulder in overhead sports. There is limited evidence to suggest that prehabilitation may help decrease injuries in adolescents, but it is unclear whether it has the same benefit in preadolescent athletes,1,21,22 and there is no evidence that strength training will reduce the incidence of catastrophic sports-related injuries in youth. Recent research suggested a possible reduction in sports-related anterior cruciate ligament injuries in adolescent girls when strength training was combined with specific plyometric exercises.23 Plyometric exercises enable a muscle to reach maximum strength in a relatively short time span through a combination of eccentric and concentric muscle contractions, such as jumping up onto and down from a platform.
RISKS OF STRENGTH TRAINING
Much of the concern over injuries associated with strength training come from data from the US Consumer Product Safety Commission's National Electronic Injury Surveillance System,24 which has estimated the number of injuries connected to strength-training equipment. The data from the National Electronic Injury Surveillance System neither specify the cause of injury nor separate recreational from competitive injuries that result from lifting weights. Muscle strains account for 40% to 70% of all strength-training injuries, with the hand, low back, and upper trunk being commonly injured areas.24,25 Most injuries occur on home equipment with unsafe behavior and unsupervised settings.24 Injury rates in settings with strict supervision and proper technique are lower than those that occur in other sports or general recess play at school.26,27
Appropriate strength-training programs have no apparent adverse effect on linear growth, growth plates, or the cardiovascular system,1,10,11,28,29 although caution should be used for young athletes with preexisting hypertension, because they may require medical clearance to reduce the potential for additional elevation of blood pressure with strength training if they exhibit poorly controlled blood pressure. Youth who have received chemotherapy with anthracyclines may be at increased risk for cardiac problems because of the cardiotoxic effects of the medications, and resistance training in this population should be approached with caution.30 Specific anthracyclines that have been associated with acute congestive heart failure include doxorubicin, daunomycin/daunorubicin, idarubicin, and possibly mitoxantrone. Youth with other forms of cardiomyopathy (particularly hypertrophic cardiomyopathy), who are at risk for worsening ventricular hypertrophy and restrictive cardiomyopathy or hemodynamic decompensation secondary to an acute increase in pulmonary hypertension, should be counseled against weight training. Individuals with moderate to severe pulmonary hypertension also should refrain from strenuous weight training, because they are at risk for acute decompensation with a sudden change in hemodynamics.31 Young people with Marfan syndrome with a dilated aortic root also are counseled against participation in strength-training programs. Young athletes with seizure disorders should be withheld from strength-training programs until clearance is obtained from a physician. Overweight children may appear to be strong because of their size but often are unconditioned with poor strength and would require the same strict supervision and guidance as is necessary with any resistance program.
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For Flak by request
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POLICY STATEMENT
Strength Training by Children and Adolescents
Council on Sports Medicine and Fitness
Pediatricians are often asked to give advice on the safety and efficacy of strength-training programs for children and adolescents. This statement, which is 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.
BENEFITS OF STRENGTH TRAINING
In addition to the obvious goal of getting stronger, strength-training programs may be undertaken to try to improve sports performance and prevent injuries, rehabilitate injuries, and/or enhance long-term health. Similar to other physical activity, strength training has been shown to have a beneficial effect on several measurable health indices, such as cardiovascular fitness, body composition, bone mineral density, blood lipid profiles, and mental health.1,2 Recent studies have shown some benefit to increased strength, overall function, and mental well-being in children with cerebral palsy.3,4 Resistance training is being incorporated into weight-control programs for overweight children as an activity to increase the ****bolic rate without high impact. Similar to the geriatric population, strength training in youth may stimulate bone mineralization and have a positive effect on bone density.5,6
Multiple studies have shown that strength training, with proper technique and strict supervision, can increase strength in preadolescents and adolescents.7,8 Frequency, mode (type of resistance), intensity, and duration all contribute to a properly structured program. Increases in strength occur with virtually all modes of strength training of at least 8 weeks' duration and can occur with training as little as once a week, although training twice a week may be more beneficial.7–12 Appropriately supervised programs emphasizing strengthening of the core (focusing on the trunk muscles, eg, the abdominal, low back, and gluteal muscles) are also appropriate for children and theoretically benefit sports-specific skill acquisition and postural control. Unfortunately, gains in strength, muscle size, or power are lost 6 weeks after resistance training is discontinued.1,13
In preadolescents, proper resistance training can enhance strength without concomitant muscle hypertrophy. Such gains in strength can be attributed to a neurologic mechanism whereby training increases the number of motor neurons that are "recruited" to fire with each muscle contraction.11,14–16 This mechanism accounts for the increase in strength in populations with low androgen concentrations, including female individuals and preadolescent boys. In contrast, strength training augments the muscle growth that normally occurs with puberty in boys and girls by actual muscle hypertrophy.12,14,17,18
Strength training is a common practice in sports in which size and strength are desirable. Unfortunately, results are inconsistent regarding the translation of increased strength to enhanced youth athletic performance.1,14,19,20 Preventive exercise (prehabilitation) refers to strength-training programs that address areas commonly subjected to overuse injuries, such as providing rotator cuff and scapular stabilization exercises preventively to reduce overuse injuries of the shoulder in overhead sports. There is limited evidence to suggest that prehabilitation may help decrease injuries in adolescents, but it is unclear whether it has the same benefit in preadolescent athletes,1,21,22 and there is no evidence that strength training will reduce the incidence of catastrophic sports-related injuries in youth. Recent research suggested a possible reduction in sports-related anterior cruciate ligament injuries in adolescent girls when strength training was combined with specific plyometric exercises.23 Plyometric exercises enable a muscle to reach maximum strength in a relatively short time span through a combination of eccentric and concentric muscle contractions, such as jumping up onto and down from a platform.
RISKS OF STRENGTH TRAINING
Much of the concern over injuries associated with strength training come from data from the US Consumer Product Safety Commission's National Electronic Injury Surveillance System,24 which has estimated the number of injuries connected to strength-training equipment. The data from the National Electronic Injury Surveillance System neither specify the cause of injury nor separate recreational from competitive injuries that result from lifting weights. Muscle strains account for 40% to 70% of all strength-training injuries, with the hand, low back, and upper trunk being commonly injured areas.24,25 Most injuries occur on home equipment with unsafe behavior and unsupervised settings.24 Injury rates in settings with strict supervision and proper technique are lower than those that occur in other sports or general recess play at school.26,27
Appropriate strength-training programs have no apparent adverse effect on linear growth, growth plates, or the cardiovascular system,1,10,11,28,29 although caution should be used for young athletes with preexisting hypertension, because they may require medical clearance to reduce the potential for additional elevation of blood pressure with strength training if they exhibit poorly controlled blood pressure. Youth who have received chemotherapy with anthracyclines may be at increased risk for cardiac problems because of the cardiotoxic effects of the medications, and resistance training in this population should be approached with caution.30 Specific anthracyclines that have been associated with acute congestive heart failure include doxorubicin, daunomycin/daunorubicin, idarubicin, and possibly mitoxantrone. Youth with other forms of cardiomyopathy (particularly hypertrophic cardiomyopathy), who are at risk for worsening ventricular hypertrophy and restrictive cardiomyopathy or hemodynamic decompensation secondary to an acute increase in pulmonary hypertension, should be counseled against weight training. Individuals with moderate to severe pulmonary hypertension also should refrain from strenuous weight training, because they are at risk for acute decompensation with a sudden change in hemodynamics.31 Young people with Marfan syndrome with a dilated aortic root also are counseled against participation in strength-training programs. Young athletes with seizure disorders should be withheld from strength-training programs until clearance is obtained from a physician. Overweight children may appear to be strong because of their size but often are unconditioned with poor strength and would require the same strict supervision and guidance as is necessary with any resistance program.
refs at site
For Flak by request
(below)
