Weight Lifting, Weight Training and Supplements
By Mark B. Levin, M.D. and Louis J. Tesoro, M.D.
The student athlete’s competitive environment often fosters the desire to increase muscle mass and strength in the hope of improving athletic performance. We are often queried regarding the advisability of “weight lifting” (lifting maximal weight to build strength and mass) and whether supplements, such as “andro”, DHEA, amino acids or minerals will help. For the reasons outlined in the pages that follow, rather than recommending “weight lifting”, we counsel families that supervised “weight training”, also termed “strength training” (performing multiple repetitions with small amounts of free-weights or low resistance on a universal gym), is more appropriate for a growing youngster. Until growth is finished (usually 18 years old in males and 16 years old in females), “weight lifting” should be avoided as the risk of musculo-skeletal injury (sprains, strains, torn muscles and fractures) is too great.
The Committee on Sports Medicine and Fitness of the American Academy of Pediatrics in June, 2001, having reviewed the scientific literature and citing 21 scholarly scientific references, made the following points regarding theoretical benefits of strength training:
1. strength training can increase strength in adolescents and preadolescents
2. gains are lost after 6 weeks if resistance training is discontinued
3. preadolescents and females will not achieve an increase in muscle mass (they are not producing necessary amounts of androgens and testosterone)
4. scientific studies have failed to confirm that improved strength enhances running speed, jumping ability or overall sports performance.
5. Evidence fails to show that strength training reduces the frequency of injuries.
Children and adolescents anticipating participation in strength training must follow these guidelines:
1. obtain a pre-participation physical examination to rule out medical conditions for which strength training could cause complications.
2. A strength training program must include warm up and cool down components.
3. Start with low or minimal weights or resistance forces. When 8-15 repetitions are easily performed, small increments in weight or resistance are acceptable (1-5 pounds at a time)
4. Exercises should include all muscle groups and be performed through the full range of motion at each joint.
5. Workouts must be at least 20-30 minutes long and be done 2-4 times per week to be effective; less than twice per week confers no benefit and more than 4 workouts per week does not increase strength while also depriving muscles of recovery time.
6. If a child’s goal is improved sports performance, practicing and perfecting skills is more beneficial than strength training; if the goal is long term health, aerobic training (running, swimming, biking, etc.), must be added to the regimen.
7. Any sign of illness or injury from strength training must be evaluated before the program is continued.
Student athletes must also be helped to understand that, as in any aspect of life, short-term gain must be balanced against long-term consequences. In light of this, be forewarned that that there have been few scientific studies published regarding “andro” (androstenedione), DHEA (dihydroepiandrosterone), creatine, or high doses of amino acids, chromium, calcium or iron. NO studies have been performed in subjects under 18 years of age as they relate to sports issues. However, according to an authoritative article written by Wendi Johnson, M.D. and published in Contemporary Pediatrics, July, 2001, we do know some of the risks from case reports and physiologic studies.
ANDRO and DHEA: These are naturally occurring hormones produced by the adrenal glands and are precursors of testosterone. They have not been well studied in athletes. They have been found to increase testosterone and estradiol (an estrogen) after low dose supplementation. They have the potential to cause increased hair growth in females, breast development in males, premature development of puberty and premature cessation of growth. They are likely to cause a positive urine drug test. One study in adults found Andro coupled with resistance training increased strength and muscle mass no better than placebo. The same authors (King, et al, JAMA, 6/2/99) found that Andro significantly reduced high density lipoprotein (HDL), the good cholesterol that is protective at high levels.
CREATINE: This compound is made in our liver, pancreas and kidneys and is deposited in muscle, heart, brain, testes and the retina. It is found in foods, particularly in meat and fish. It participates in the metabolic production of cellular energy. There is a maximum amount of creatine that muscles can accommodate. So, extra creatine is not retained in the body. Exercise and carbohydrate ingestion appear to enhance creatine uptake from foods. Caffeine reduces its uptake. It causes an increase in muscle fluid retention, giving the false impression of increase in dry muscle mass. Although creatine supplementation enhances repetitive efforts (intensity and duration of weight training workouts), it does not improve endurance or one-time all-out efforts. Side effects include headache, water retention, abdominal pain and diarrhea. Users have a higher incidence of muscle strain and are more likely to suffer dehydration or heat illness due to fluid shifts in the body. One case of kidney failure has been reported.
AMINO ACIDS: Increasing protein substrate intake over the maximum 1.8 mg/kg/day required by resistance trained athletes offers no increased benefit in muscle mass or strength. Increased calorie intake will allow the body to make enough protein to satisfy the needs of athletes without other supplements. Studies comparing carbohydrate ingestion with amino acid and mineral supplementation show no difference in increased lean muscle mass. Exercise and calories, not excess amino acids, are the keys to muscle building. Too much protein risks acidifying the blood excessively. A specific amino acid, glutamine, has been implicated in the decreased immune function of overtrained athletes. Supplementation with leucine has not translated into improved performance or increased muscle mass. Although HMB (beta-hydroxy-methylbutyrate) , a metabolite of leucine, can increase lean mass when taken in large doses and coupled with resistance training in adults, there are no studies in youths. Supplementary Carnitine, found naturally in meat and dairy products, has not been found to have any effect on performance in trained marathon runners.
CHROMIUM: This mineral is released from body stores in response to a rise in blood insulin. It is found in brewer’s yeast, nuts, asparagus, prunes and mushrooms. Supplementation does not decrease body fat, nor increase lean body mass or strength. One case of acute renal failure has been reported after high dose supplementation.
CALCIUM: Contrary to other minerals, calcium supplementation is important, particularly for female athletes, who are at increased risk of decreased bone calcium due to the hormonal response to irregular menses. Caffeine, cigarettes smoking and alcohol consumption, and large amounts of meat or soda (because of their high phosphorous content) promote calcium losses. Adolescent girls need 1200 to 1500 mg per day. The appended list displays the calcium content of various foods.
IRON: Like calcium, assuring iron sufficiency is important. Athletes have increased iron losses through perspiration, stool and urine. Females also require extra iron intake to replace menstrual losses. See the appended list of foods high in iron. Adolescent girls need 15 to 18 mg per day. Males require 12 mg per day through adolescence and 10 mg per day in adulthood.
The market for enhancers and supplements in enormous. The government does NOT regulate these products with the exception that a manufacturer my claim anything for a substance, even without scientific study, except that it “treats, cures, mitigates, diagnoses or prevents a disease”. There are no standards for purity, quality or quantity of active compounds and manufacturers need not publish benefits or precautions. Only after a supplement has been proven to be unsafe can it be removed from the market.
We recommend that athletes get their nutrients from healthy foods, that they increase their protein intake to 1.4 to 1.8 g/kg/day (the RDA is 0.8 g/kg/day) during strength training, that they increase their calorie intake to 25-30 cal/kg/day (from the usual 20 cal/kg/day), that they get adequate amounts of calcium and iron from foods (see appended list) and that they carbohydrate load (eat rice, pasta, potatoes, etc.) for three days before an important athletic event. Adequate amounts of chromium are found in brewer’s yeast, nuts, asparagus, prunes and mushrooms.
Coupled with practice and perfecting skills, and a sound strength training program, our children can enjoy the emotional and health benefits of athletics without the attendant risks imposed by ingesting unproven and potentially dangerous substances.
rights reserved, The Pediatric Group, P.A. 2001
Dr. Mark B. Levin
Dr. Levin has been a member of the staff at The Pediatric Group since 1977. Currently an attending Pediatrician at the Medical Center at Princeton, he has been Chairman, Department of Pediatrics, Medical Center at Princeton, 1984 to 1986, 1989 to 1992, and past President, Medical and Dental Staff, Medical Center at Princeton, 1987 to 1988. Dr. Levin has served on numerous Departmental and hospital committees. He has published original articles both while at Upstate Medical Center in Syracuse and at The Pediatric Group. He has a wife and three children. Dr. Levin enjoys alpine skiing, jogging, hiking and camping, travel, computers and racquetball.
Dr. Louis J. Tesoro
Dr. Tesoro has been a member of the staff at The Pediatric Group since 1988. Dr. Tesoro is Attending Pediatrician, Medical Center at Princeton, 1988 to present. He has served on several Departmental and hospital committees and was Chairman, Department of Pediatrics, Medical Center at Princeton from 1996 - 2000. He has lectured at the Universiy of Pennsylvania and has published original articles both while at The Children's Hospital of Philadelphia and at The Pediatric Group.Pediatric Group
©All rights reserved, The Pediatric Group, P.A. 2001