Youth Strength Training, a review of research.
by Jared Bidne
Two of the most frequently asked questions I get from parents about children and strength training are; “Is it safe for kids to lift weights?” and “At what age can they start lifting?” Despite this grossly exaggerated myth, the National Strength Conditioning Association (NSCA), the American College of Sports Medicine (ACSM), exercise physiologists and the American Academy of Pediatrics support the implementation of strength and resistance training programs for young children.
Is it safe for kids to lift weights?
The answer is “YES.” The organizations mentioned above support the implementation of strength and resistance training programs, even for prepubescent children, that are monitored by well-trained adults and take into account the child’s maturity level. A growth plate fracture has not been reported in any youth resistance study that adhered to established training guidelines. Strength and resistance training will not affect growth height, delay or accelerate growth or maturation in boys or girls. Bone scans of children who have done regular lifting reveal a significantly larger bone density than those who do not lift weights. Even 1 rep max testing in children is safe. (3)
* If appropriate training guidelines are followed, regular participation in a youth strength-training program has the potential to increase bone mineral density, improve motor performance skills, enhance sports performance, and better prepare young athletes for the demands of practice and competition.” (2) (3)
* A study of young male powerlifters found that high-intensity resistance training is effective in increasing lumbar spine and whole body bone mineral density. (9) (10)
* With proper supervision, children who participate in a strength training program are not at an increased risk for injury compared to children and youth who do not participate in such a program.(5) (9) 10)
Proper resistance training is incredibly effective at stimulating growth and development! (10) I have trained several athletes boys and girls, that started training at age 9 and have now obtained body heights that are above average. I have even had some kids that were below average in height and weight that are now above average.
At what age can kids start lifting weights?
According to Exercise physiologists and the NSCA there is no minimum age requirement at which children can begin resistance training. Children should have the maturity to follow directions and should be eager to try this type of activity. In general, if children are ready for sport participation, then they are ready for some type of resistance training program. Children as young as 6 years have benefitted from strength training. Improvements in the long jump, vertical jump, 4o-yd dash, and agility run times have been observed in children who participated in a resistance training program. (10) I track all my athletes at Explosive Mechanics and have their results to back up the research. However, we must remember that children are not adults, their program design should be to introduce the body to the stresses of training and to teach basic technique. After a foundation is established, more advanced training can be introduced and the amount of exercises and the weight lifted can be increased. A certified professional trainer who is familiar with working with children should design a program specific to the needs of the child.
Too much sport not enough training
Today athletes are spending more time participating in various sports or practicing their sport and neglecting training, which helps with sporting performance and injury prevention. As an effect, the incidence of injury in all youth sports has seen a dramatic increase over the past 10 years due to greater sport participation and not enough dedicated training time. Children cannot “play” themselves into shape, because the load and demands of sport activity do not stimulate improved muscle and connective tissue growth and strength. Considerable biomechanical research has shown that the stresses imposed on the body by common sporting activities such as running, jumping, and hitting generally are far greater (by as much as 300%) than those imposed by powerlifting or olympic lifting.
Nevertheless, it is apparent that for young athletes to maintain a physical advantage over their untrained peers, continued training of more than 1 day a week is needed. In one study, after 20 weeks of strength training, maintenance performed once a week was not enough to maintain the strength gains of prepubescent children.
Strength and resistance training can be a safe and effective means of increasing sporting performance and injury prevention for athletes of all ages. Early prepubescent lifting will not stunt a childs growth development or speed up the maturation process. Parents need to find time to get their child into a strength and conditioning program for physical development and if nothing else injury prevention. Any exercise or activity for children have risk as well as benefits. Although strength training injures may occur, the risk can be minimized with appropriate program design and adult supervision. A certified professional trainer who is familiar with working with children should design a program specific to the needs of the child.
1. American Academy of Pediatrics Policy Statement. Strength, Weight and Power Lifting, and Body Building by Children and Adolescents. Pediatrics. 1990; 5: 801-803.
2. Faigenbaum, A.D. Strength training for children and adolescents. Clinical Sports Medicine. 2000; 4: 593-619.
3. Faigenbaum, A., W. Westcott, R. La Rosa Loud, and C. Long. Delmonico, and L.
Micheli. Relationship between repetitions and selected percentages for the one
repetition maximum in healthy children. Pediatr. Phys. There. 10:110-113. 1998
4. Faigenbaum, A., W. Westcott, R. La Rosa Loud, and C. Long. The effects of
different resistance training protocols on muscular strength and endurance
development in children. Pediatrics 104:E5. 1999
5. Guy, J.A., Micheli, L.J. Strength training for children and adolescents. Journal of the American Academy of Orthopedic Surgeons. 2000; 1: 29-36.
6. Heinonen, A., Sievanen, H., Kannus, P., Oja, P., Pasanen, M., Vuori, I. High-impact exercise and bones of growing girls: a 9-month controlled trial. Osteoporosis International. 2000; 12: 1010-1017.
7. Malina, R. Physical activity and training: Effects on stature and the adolescent
growth spurt. Med. Sci. Sports Exerc. 26:759-766. 1994
8. Payne, V.G., Morrow, J.R., Johnson, L., and Dalton, S.N. Resistance training in children and youth: a meta-analysis. Research Quarterly for Exercise and Sport. 1997; 1: 80-88.
9. Tsuzuku, S., Ikegami, Y., and Yabe, K. Effects of high-intensity resistance training on bone mineral density in young male powerlifters. Calcified Tissue International. 1998; 4: 283-286.
10. Zatsiorsky M. Vladimir, Kraemer, W. J. Science and Practice of Strength Trainng (2nd ed.). Champaign, IL: Human Kinetics, 2005.
STRONG-HER THE ARTICLE
By Jared Bidne CSCS D*
Over the past 30 years, the participation of women in sports has grown dramatically. With the greater demands for power, speed, and intensity in women’s sports there is a definitive need for total body power. For years many women “played themselves into shape,” which placed them in situations where their bodies were not ready to take on the demands of the sport. Females need strength for power, do not need to fear “getting big”, and need to understand strength training.
The Females Need For Strength
Female athletes in sports such as tennis, basketball, and volleyball often neglect strength training during high school years. While in college they find their athletic performance is limited by poor physical development, and try to develop strength as fast as possible giving them an increased injury risk and/or they end up dropping out of the sport. I have had several of my D1 female athletes tell me many of their scholarship athletes end up quitting.
In terms of absolute strength, women generally have about two thirds the strength of men. Most of the difference being in the upper body, because women tend to have less muscle mass above the waist. In many sports it is this physical difference that will limit performance outcomes (ie. hitting a softball, shooting distance in basketball, hitting power in volleyball, throw in distance in soccer).
Females are also put together a little differently than males. Women have thinner ACL’s than those of men, but with strength training women can increase ligament and tendon strength, thus reducing injury risk. In males, the type II fibers of the vastus laterals (outside thigh muscle) are larger than the slow fibers, but the opposite tends to occur in females. As females train they can alter the contractile properties of the muscle and make one type of fiber act like or become another type.
Here are a few benefits of strength training for women.
* Improved physical skills running agility and jumping
* Enhanced bone strength and reduce the risk of osteoporosis
* Stronger connective tissue to increase joint stability
* Increased sports performance
* Decreased body fat
* Increased metabolism
* Improved self-esteem and confidence
Many women have a fear of “getting big” or developing too much muscle. This myth has limited their performance. The fear of getting big is unfounded, and the development of strength in women is extremely important. Strength and overall body power is more of a neuromuscular effect than muscular. In other words, strength is not about muscle size, but of the appropriate muscles powerfully contracted by effective nervous stimulation. If training is done properly more neurons and the appropriate fibers will be activated for creating more strength and power without any unnecessary size. Here are a few things to consider.
Due to neuromuscular effects, women can increase their strength at the same rate or faster than men. I have had a 13 year old 125 pound girl out squat some of my high school males. I have even had some females out jump high school males. Although absolute strength gains are often greater for men, trained women can out perform the average guy. There is no reason why training programs for women need to be different from those of men. The programs should be designed to improve the performance of the nervous system and muscles regardless of sex. However, it is important that female athletes avoid prolonged periods of inactivity because they experience a faster detraining effect (loss of gains) than males.
Benefits of lifting:
I hear some high school females talk about participating in high school weight training. Most, if not all high school weight training programs are geared toward the schools football program. Other students may participate, but more than likely they will not experience the same attention as the main sport players. Most high school programs have their lifters go through a mass building phase which is not necessary for most athletes. College training is sometimes no better, my female athletes will come back in the summer weaker, slower, and jumping less. Women need heavy resistances in order to develop maximum strength, and they should occasionally perform their exercises at or near their max. Light weight more reps will enhance local muscular endurance with little or no carryover to absolute strength. People are so into the type of gyms that are popping up all over the country and the latest fad on TV. The popular things may produce aesthetic results of the average non-competitive athlete, but will have limited value to the serious athlete. The aim of the popularity stuff is general fitness and does not take in account the different qualities of strength and the effects of neuromuscular performance.
Strength training for female athletes is extremely important! An effective training program can prepare a females body for the physical demands of sport while preventing injury. The fear of getting big should be put to rest. Females have smaller muscle fibers and do not have the levels of testosterone to build large muscle mass. The training programs should be designed to improve the performance of the muscles regardless of sex. As with men, progress and fine-tuning of the strength program is needed for continued progress. The popularity of fitness trends are aimed to sell not improve.
Baechle, Thomas, R. Earle, W. Roger. Essentials of Strength Training and Conditioning (2nd ed.). Champaign, IL: Human Kinetics, 2000.
Wilmore, Jack H, David L. Costill. Physiology of sport and Exercise. 2004.
Zatsiorsky M. Vladimir, Kraemer, W. J. Science and Practice of Strength Training (2nd ed.). Champaign, IL: Human Kinetics, 2005.
What is Creatine?
Creatine is an amino acid like molecule constructed of three different amino acids Arginine, Glycine and Methionine. Our body makes a couple grams per day and the rest is obtained through our diet. It is used in muscle cells to store energy for sprinting and explosive exercise. There is about 1 g of creatine in 250 g (half a pound) of raw meat. Meat and fish are the best sources and there is no creatine in plants, therefore vegetarians have low creatine levels. 95% of creatine is stored in skeletal muscle and the other 5% in the brain and heart. Adults need to ingest about 2g/day to make up for urinary loss.
* Short term creatine supplementation can improve maximal effort muscle contractions by 5-15%, single effort sprint performance by 1-5%, and work performed during repetitive sprint performance by 5-15%.
* Creatine supplementation for 1-2 months during training has reported to promote further gains in sprint performance 5-8%, plus gains in strength 5-15% and lean body mass 1-3%.
* A British study from the university of Swansea found that creatine monohydrate improved memory and reaction times in vegetarians.
* Creatine also has shown positive effects on strength in untrained people, even in the absence of training.
Somewhere along the line, creatine got a bad rep in that it somehow damages your kidneys. The likely cause of this false accusation is failing to distinguish between creatine (the supplement) and creatinine, the diagnostic measurement for kidney problems. If serum creatinine levels are high, your kidneys could be malfunctioning. Creatinine is also the waste product of creatine, and since creatine consumption increases your creatinine levels, this creates a false positive. Over half a dozen studies have been conducted checking kidney function after creatine consumption – and no problems were found. Unless you have a pre-existing medical condition, creatine use should not damage your kidneys or liver. In one study which tracked healthy athletes over a five year period, football players who used creatine levels up to 15g/day showed no effect on markers of renal or kidney stress. Another study conducted by Oregon Health Sciences showed the kidney function of 36 healthy male and female athletes who consumed 10g/day did not adversely affect kidney function after a 12 weeks. Arkansas State University conducted two studies that found creatine use by 61 Division I athletes during training camps had no effects on muscle cramps, injury, or illness. These athletes used 15-25g/day and showed more improvement in strength gains and sprinting speed. Many people have misconceptions about the supplement because they get their information from the wrong sources. Cramping, dehydration, muscle injuries, and even death have often been associated with creatine. Some unreliable claims have suggested that athletes training in intensely hot or humid conditions might experience several muscle cramps while taking creatine. No study has reported that creatine supplementation caused cramping, dehydration, or changes in electrolyte concentrations. This study was done on highly trained athletes during intense training in a hot and humid environment. A number of reports in the media suggest that creatine supplementation can produce dehydration. There are no such studies supporting this claim. One of the most poorly researched press reports suggest that creatine may have been involved in the sudden deaths of three wrestlers. These athletes died suddenly while exercising in the heat wearing rubber suits while trying to cut weight before competition. The Centers for Disease Control and Prevention and the Food and Drug Administration decided to investigate whether creatine was involved in these deaths or not. The CDCP reported the results of the investigation and 2 of the wrestlers had not taken creatine and the other one stopped taking creatine 3 months before his death. These deaths were officially attributed to hyperthermia, heart failure, and heat exhaustion (Antonio). Several studies found that no increase was found for musculotendinous stiffness nor was there a report of muscle strain injuries (5). In a second study there were also no differences in the reported incidence of muscle injury, cramps, or any other side effects between the supplement group and placebo group. The groups showed no long-term side effects of creatine supplementation except for an increase in lean body mass (4). A third group reported no side effects at all (3). There was also one study done on renal function and again creatine showed no side effects.
Another misconception about creatine is that once one stops taking the supplement his or her gains will go away. One study showed that is not true. The gains in lean body mass were maintained while ingesting creatine (5 g per day) during a 10-week period of detraining and in the four weeks after supplementation stopped (6). Following directions that the supplement advises and drinking plenty of water can eliminate some of the possible side effects often associated with creatine.
Our skeletal muscles perform work through the breakdown of Adenosine triphosphate (ATP). ATP is broken down into Adenosine diphoshpate (ADP) and the process of turning ATP into ADP gives our muscles the energy they need to contract. ADP cannot be used to create energy for our muscles, but breaking the phosphate from ATP can. The continuation of work is based on the maintenance of ATP at a rate equal to the rate of its use, so the faster we restore ATP the faster our muscles get the energy they need to contract. The cells in our body also contain another high-energy phosphate molecule that stores energy. This molecule is called phosphocreatine or PCr (also called creatine phosphate). Unlike ATP, energy released from breakdown of PCr is not directly used to create cellular work. Instead, it helps ATP to maintain in a relatively constant supply. The release of energy from PCr is initiated by the enzyme creatine kinase, which acts on PCr to separate the P from creatine. The energy released then can be used to combine P to ADP, forming ATP. Once we have ATP we break it down into ADP and the process starts over.
During exercise ATP is maintained at relatively constant level, but the PCr is steadily declining because it is used to replenish ATP. ATP and PCr levels are low in our bodies; therefore our capacity to maintain constant ATP levels with energy from PCr is limited. Our ATP-PCr stores can only maintain energy need for a high intense activities lasting 3-15 seconds such as weightlifting and sprinting. Beyond that point our muscles must rely on other energy sources such as carbohydrates, fats, and proteins to provide for the production of ATP. They are much slower at creating ATP because they take longer to convert to a usable energy source.
About 95% of creatine is stored in skeletal muscle and about 60-70% of that is stored in the form of phosphocreatine. By increasing creatine intake the PCr levels in our bodies will increase, thus enhancing the ATP-PCr energy system by better maintaining muscle ATP levels.
Creatine allows for more phosphocreatine to be stored in the body therefore, ATP can be replenished for a longer amount of time. An event lasting 3-15 seconds could last 3-25 seconds with the aid of creatine supplementation. By extending the ATP-PCr system an athlete can get a few more reps in during each set of a workout. By doing a few more reps in each set allows the muscles to be pushed a little harder with each workout. It usually takes about 3 days of supplementing with creatine for the athlete to experience the effects of creatine. I am a pretty well trained athlete and I have experienced nothing but positive results with creatine.
One time I was training for 6 months off creatine and the week I decided to start using creatine again I went in for a chest work out on Monday and for the bench press I did 315 pounds 5 times on my first set and 4 times on my second and third sets. When I went in on Thursday to do the same work out I did 315 pounds 8 times on my first set, 7 times on my second set and for my third set I did 5 reps. I started using creatine on Monday morning and by Thursday afternoon I could already see the effects.
Antonio, Jose, Jeffrey R. Stout. Sports Supplements. Lippincott Williams and Wilkins
Groeneveld GJ, et al. Few adverse effects of long-term creatine supplementation in a placebo-controlled trial. Int J Sports Med. (2005)
Gualano B, et al. Effects of creatine supplementation on renal function: a randomized, double-blind, placebo-controlled clinical trial. Eur J Appl Physiol. (2008)
Gualano B, et al. Effect of short-term high-dose creatine supplementation on measured GFR in a young man with a single kidney. Am J Kidney Dis. (2010)
Poortmans Jr, et al. long-term oral creatine supplementation does not impair renal function in healthy athletes. Med Sci Sports Exer 1999, 31(8):110-1110.
Poortmans Jr, Francaux M. Adverse effects of creatine supplementation. Sports Med 2000;30:155-170
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