The KickStart Files

Recently, a client called us with an urgent request. She is a PE teacher at a Middle School in San Diego, and she’s just opened up a really nice new fitness center. Her room includes a full set of weight machines, sized and weighted specifically for children.

She’d been running the kids through the center for about two weeks (it’s been a smash hit and someday soon I’m going to blog on it) when she received a call from a VERY concerned parent. This woman had discussed the new fitness room with her child’s gymnastics coach, who had informed her in no uncertain terms that children should NEVER be allowed to do any type of resistance (i.e. weight) training until they’d passed through puberty, because it could “damage the bone plates”. The parent was alarmed and concerned and she really let the PE teacher have it. She said she was going to keep her child out of the fitness room, and threatened to encourage other parents to do the same.

How, the teacher wanted to know, should she respond?

At KickStart, we run across this issue all the time. The notion that prepubescent and adolescent children should not engage in resistance training has been around for a long time. Frankly, it shares a lineage with other outdated notions such as the concept that PE for females should be limited to moderate, noncompetitive activities.

The truth is that current thinking in the relevant fields (pediatrics, sports medicine, physiology, etc) holds that properly conducted, age-appropriate strength training is beneficial to prepubescent and adolescent children. Of course, it’s the “properly conducted, age appropriate” part that is most important. Turning a bunch of unsupervised 11-year olds loose on a gym full of adult-sized weightlifting equipment would not meet the “properly conducted” threshold! The bottom line is that parents like the mother in San Diego have a right to be concerned when their children engage in strength training, particularly with weights. Correspondingly, PE teachers, trainers, and coaches have an obligation to be well informed about the basics of youth resistance training.

So, I thought it would be useful to share, in the form of an FAQ, the “response package” I put together for our harried teacher in San Diego. Readers are also invited to avail themselves of the small library of pdf files we’ve put together on the subject; I’ll continue to add to these as I find additional resources I think can be helpful.

I’ve also included a short list of weight lifting terms and definitions at the end of this entry that might be useful for those who don’t have a lot of experience in the area.

Generic but necessary Disclaimer: anything written here is either quoted research or an opinion based on that research. I’ve made every effort to utilize only reputable sources. Any youth resistance program should be developed, validated, and supervised by knowledgeable resources. These would include pediatricians, certified and experienced youth fitness trainers whose credentials come from a reputable source, or other similarly qualified professionals.

FAQ

Is it safe for prepubescent and adolescent children to engage in strength training?

Today, many recognized health organizations, including the American College of Sports Medicine(ACSM) , the American Academy of Pediatrics (AAP) and the National Strength and Conditioning Association (NSCA), support children’s participation in appropriately designed and competently supervised strength training programs.

While there is no doubt that strength training can potentially result in injury, this is hardly the right criterion to use when evaluating an activity. It would be difficult to find an activity in any Physical Education class that does not present the possibility of injury (go ahead, try). Strength training, in fact, is extremely safe when employed correctly. Here is an interesting study produced in the UK that specifically debunks a lot of misconceptions about the relative safety of weight training for kids.

It is of course important to remember that prepubescent and adolescent children can not achieve the same type of gains in muscular size and strength that a dedicated adult weightlifter will realize (particularly an adult male). This is a critical point: children should not be lifting weights to “get big” or “get ripped”; this is where bad form and injury can occur. Instead, focus on the realistic benefits of youth strength training.

Okay, what are the realistic benefits of youth strength training?

Studies have shown that kids can make substantial gains in muscle strength through consistently applied resistance training. In prepubescent children, this has more to do with important neural adaptations to strength training (muscle fiber recruitment), vs. growth due to hypertrophy of muscle fibers. Increases in muscle size are largely driven by naturally occurring hormones such as testosterone, HGH, and insulin, most of which cannot be produced in large quantities by children*. Early electrical activation of nueral “motor units” in muscle tissue lays the groundwork for increased muscle capacity, strength, and growth in the future.

(* It’s interesting that lack of testosterone is often cited as a reason that weightlifting is not suitable for children. Wouldn’t the same apply, then, to female adults, who produce a fraction of the testosterone as adult males?)

Additionally, youth weight training has been found to provide real benefits . Dr. Thomas D. Fahey, EdD, head of the Department of Kinesiology at the California State University, Chico writes in the ISSA’s Youth Fitness Trainer textbook that:

“More than 15 studies show that kids make substantial gains from lifting weight s in strength and msucle tone and concurrently lose fat. More important, kids can do it safely without damaging fragile bone growth centers. Weight lifting exercise is particularly good exercise for girls because it helps build bone mass, strengthen bones, muscles, and tendons, and prevent fractures during the middle years when bone mass typically declines at a faster rate in concert with approaching menopause”

While the American College of Sports Medicine reports that:

“Properly designed and competently supervised youth strength training programs may not only increase the muscular strength of children and adolescents, but may also enhance motor fitness skills (e.g., sprinting and jumping) and sports performance. Preliminary evidence suggests that youth strength training may also decrease the incidence of some sports injuries by increasing the strength of tendons, ligaments and bone. During adolescence, training-induced strength gains may be associated with increases in muscle size, but this is unlikely to happen in prepubescent children who lack adequate levels of muscle-building hormones. Although the issue of childhood obesity is complex, youth strength training programs may also play an important role in effective weight loss strategies.”

Not to mention that a lot of kids who are otherwise uncomfortable in PE classes or other physical activities are likely to find strength training less intimidating and more enjoyable than many other standard Phys Ed activities (more on this below).

More specifically, what, exactly, are the benefits of strength training for obesity and clinical overweight?

Okay, I admit, I cooked up this question because I find the answer, or part of the answer, fascinating and useful. Authorities seem to agree that there is evidence to support the notion that strength training promotes weight loss and improved body fat percentage/BMI. This seems to be true for a number of reasons, some of which are physical, e.g. healthier muscles (having a higher percentages of recruited fibers) encourage increased movement which results in weight loss, etc. But it’s the psychological component that is most compelling. According to the official journal of the American Academy of Pediatricians:

“Obese children often prefer strength training because it does not require agility or aerobic ability, and the benefits become apparent within as little as 2 to 3 weeks. Because of their added body mass, overweight participants also tend to be stronger than their peers, giving them a relative psychological advantage. Recent studies have shown that obese students are more compliant and increase their free fat mass when weight training is added to aerobic exercise or a standardized energy-reduction diet.”

Weight training is a great way to “lower the bar” of entry into physical activity for overweight kids; it can provide an opportunity to succeed and fairly rapid results. Perhaps most importantly, it avoids -maybe even reverses- some of the social trauma experienced by heavy kids on the playing field, track, or court.

When can a child begin strength training?

The consensus seems to be that if an 8 year old child is ready for participation in organized sports or activities (e.g. little league baseball or gymnastics), then s/he is ready for some type of strength training, provided the child is mentally ready and the activity is part of a fun, well-rounded fitness program. In an article on their website, the Mayo clinic states that:

“During childhood, kids improve their body awareness, control and balance through active play. As early as age 8, however, strength training can become a valuable part of an overall fitness plan — as long as the child is mature enough to follow directions and practice proper technique and form.”

It’s important to remember that “fitness” is in some ways an inappropriate term to use with children. Prepubescent children are not capable of, nor interested in, the kind of sustained intense workouts that result in substantial gains in strength and endurance in adults. While some of us grow to love rigorous, intense workouts, it’s often only because we learned at an early age to enjoy physical activity. Any fitness program designed for children should focus on developing a positive association with the body and with movement.

So, what type of training is appropriate?

“Strength training” methods* take a wide variety of forms, including:

• Isometric/Calisthenic: utilizes bodyweight or muscular force against “static” objects.
• Free weights:including dumbbells, barbells, medicine balls, and any other object that is lifted repeatedly.
• Weight Machines: Including selectorized (stacked weights lifted via a cable and pulleys - you “select” the weight with a pin), plate-loaded (weight plates are manually loaded onto and off of the machine), and hydraulic/liquid resistance.

*Not to be confused with training styles, which would include weightlifting, powerlifting, bodybuilding, etc.

Theoretically, kids can use any/all of these as long as the weight is appropriate and the form is good. It is also critical to make sure that the equipment is appropriately sized. Weight machines should be designed explicitly for kids, or should be adjustable to a size small enough to accommodate the young trainer. If a child has to stretch or “come off” the back pad to lift the weight, the machine is too big!

Even though you can conceivably invoke any of the training methods listed above for kids of any age, from a practical perspective it is probably best to take a graduated approach. e.g.:

• Very young or “de-conditioned” children who are just starting out should engage in strength exercises that utilize only their own bodyweight and/or muscular power without added external weight. This includes Calisthenic and Isometric exercises. Be creative with younger kids: climbing is a great bodyweight resistance exercise and a lot more fun than pushups!
• Kids who have become comfortable with using muscles in lighter, body weight or isometric exercises, and are old enough to participate in organized sports, can graduate to light “weight” training. Elementary kids can have a lot of fun doing free weight exercises in combination with Fitness Balls, BOSU balls, or other items. This has the benefit of incorporating core/stability muscles, balance, and kinesthetic awareness. A kid sitting on a fitness ball and doing shoulder presses with 2lb dumbbells has to focus on a lot of physical input, and this makes the activity both more athletic and more enjoyable.
• Younger kids can also use weight machines, but should start with hydraulic resistance machines which are impossible to “slam” and provide a very controlled range of motion and velocity.
• Middle school and Jr High kids can graduate to somewhat heavier free-weight work as long as PROPER FORM and PACE is practiced and enforced by the trainer.
• Selectorized weight machines are good additions for adolescents, as the equipment has grown-up look and feel, yet it still enforces control on range of motion.

Regarding progression: as noted in the Journal of the AAP, it is probably better to use physical maturity, rather than chronological age, as a gauge to assess whether a young person is ready to move on to a more advanced strength training activity. That 6′ tall 7th grader with the moustache is probably capable of handling more than his 4′ 5″ buddy who hasn’t yet entered puberty!

What are the risks? (or, what about those “bone plates”, anyway?)

The growth plates are the epiphyseal plates (or growth plates). These are essentially layers of cartilage at the end of the bones of children and adolescents. The plates are the point from which ossification occurs, i.e. bone grows, and they can be damaged by traumatic or repetitive impact. Weight lifting is often the first “culprit” thought of when people hear the term “damaged growth plates”, but in fact, carefully controlled resistance training is a very safe way of exercising while protecting those plates. Remember that resistance training is actually safer and more controlled than many of the activities active children engage in, including skiing/snowboarding, skateboarding, and organized field sports. (If you haven’t checked out this study from the UK, here’s the link again). Anyone who can look at you and say, with a straight face, that tackle football is safer than weight training for a pre-pubescent or adolescent body is, frankly, out of his or her tree.

Many readers will be familiar with Osgood-Schlatter disease, which is a fairly common, painful knee conditioned experienced by many young athletes. While the specific pathology of the disease is still debated, most authorities now agree, as cited in this excellent article by Valentin Uzonov, that repetitive impact on the still-developing bone ends is the most important contributing factor. That’s why we see it so frequently in young gymnasts, basketball and soccer players. The point: we tend to overlook the risk inherent in widely accepted/popular activities, while overplaying the risks associated with strength training. In fact, strength training, as an integrated component of an overall training scheme, can help to protect young athletes from sports injury.

The notably (and appropriately) conservative American Academy of Pediatrics comments on the safety of youth strength training as follows (citations left intact, bold and italicized formatting are my additions)

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“

Furthermore, a very interesting study conducted by the NCSA demonstrated that traditionally verboten 1 Rep Maximum (1RM) lifts have no negative affect on the growth plates, nor any other negative affect, for that matter. (Please note that this was a clinical study and the objective was to determine whether 1RM could be used to evaluate/test children in a clinical setting. 1RM as a training principle is definitely best left to post-pubescent training.

A final note on this topic (safety): it’s important to keep a clear head when discussing youth resistance training. Remember to put everything in context. Most active children spend a good deal of their childhood engaging in activities that are far riskier than a safely executed weight training program. I’m not suggesting that children should be prevented from playing field sports or participating in gymnastics or riding bikes around the neighborhood - I’m suggesting that perspective is important when evaluating risk!

When can a youth engage in “real” weight training?

When they are not children anymore; i.e., when they have passed through puberty. Anyone who has parented, taught, or coached High School kids knows that there is usually a huge physical difference between Freshmen and Seniors, particularly among males. Most Freshmen are still kids, physically, while Seniors are men and women (again, physically). While the turbulent growth period that is puberty is in full swing, the risk of damage to young bodies remains. Football coaches and others would do well to remember this before encouraging 13 and 14 year old students to hit the power cage with their older peers.

Some basic youth strength training guidelines, compiled from the recommendations of the AAP, the NSCA, and other sources:

• LOW WEIGHT, GOOD FORM, HIGER REPETITIONS.
• Strength training is just a part of any youth activity or training program. While important, it is far less significant in terms of future performance than skills training. Balance is key in any program.
• In a private or commercial setting, an instructor to child ratio of at least 1 to 10 is recommended to provide adequate supervision and instruction. This is not always possible in a school setting, so teachers should rotate small groups of children into the weight area one at a time, and observe the initial exercise activities closely.
• When children are learning exercises for the first time, they should be using no weight at all or very little until the motion is learned.
• Ensure that the training environment is free of hazards, and that adequate space is allotted for the movement of weights, etc.
• Perform calisthenics and stretches before and after strength training.
• Begin with 1 set of 10 to 15 repetitions on 4 to 8 exercises that focus on the major muscle groups of the upper and lower body. Always err on the side of caution when adding weight or resistance.
• Start with a relatively light weight and high reps and increase the load and decrease the reps as strength improves. Progressive resistance exercise requires successful completion of 8 to 15 repetitions in good form before increasing weight or resistance.
• Two to three training sessions per week on nonconsecutive days is sufficient.
• Increase the weight gradually as strength improves. Generally a two to five pound increase in weight is consistent with a 5% to 10% increase in training intensity. Progression can also be achieved by increasing the number of sets ( up to 3) or number of exercises, or the duration of the exercise.
• “Static” lifting or resistance exercises (e.g. Pectoral Press machines, seated Shoulder presses, etc) should be combined with dynamic, “core” exercises. This promotes overall body strength, core stabilization, coordination and agility. E.g. – instead of doing simple shoulder presses, have the students sit on a Fitness Ball while doing them (but lower the weight!)

A Brief Set of Weight Training Terms and Definitions (courtesy American Academy of Pediatrics)

• Strength training: The use of resistance methods to increase one’s ability to exert or resist force. The training may utilize free weights, the individual’s own body weight, machines, and/or other resistance devices to attain this goal.
• Set: A group of repetitions separated by scheduled rest periods (eg, 3 sets of 20 reps).
• Reps: Abbreviation for repetitions.
• One rep max (1RM): The maximum amount of weight that can be displaced in a single repetition.
• Concentric contraction: The muscle shortens during contraction (eg, arm curl, leg press).
• Eccentric contraction: The muscle lengthens during contraction (eg, lowering a weight).
• Isometric contraction: The muscle length is unchanged during contraction (eg, wall sits).
• Isokinetic contraction: The speed of muscle contraction is fixed through the range of motion.
• Progressive resistive exercises: An exercise regimen in which the athlete progressively increases the amount of weight lifted and/or the number of repetitions. The more repetitions, the greater the work performed and the greater the endurance development. The more weight lifted, the greater the strength development.
• Weight lifting: A competitive sport that involves maximum lifting ability. Olympic weight lifting includes the “snatch” and the “clean and jerk.”
• Power lifting: A competitive sport that also involves maximum lifting ability. Power lifting includes the “dead lift,” the “squat,” and the “bench press.”
• Body building: A competition in which muscle size, symmetry, and definition are judged.