Most people are aware that children in developed nations are experiencing epidemic levels of obesity, and that this problem is, in large part, associated with physical inactivity. However, the standard fitness recommendation to get more cardiovascular exercise may not be the best advice for overweight, underactive children. The fact is, very few children choose to spend 20 to 30 minutes doing any kind of continuous endurance exercise, regardless of the benefits or incentives. Most youngsters prefer to play hard or run fast for 30 to 60 seconds, rest a minute or two, then repeat their performance, essentially alternating brief bouts of vigorous exercise with longer recovery periods.
Ideally, children should have access to exercise programs that meet their physiological needs and match their personal activity patterns. Fortunately, it is possible to provide such exercise programs through sensible strength training—and the beneficial effects typically exceed most people’s expectations.
Strength training for kids not only offers many advantages over other types of exercise; it also appeals to children’s activity preference to alternate brief bouts of high-effort movement with longer periods of rest/recovery. Strength training exercises for kids also provide visual reinforcement, because young exercisers can easily see how much weight they are lifting and how much progress they have made.
One of the best features of strength training for kids is the success rate that overweight boys and girls experience. Unlike most athletic activities (e.g., running, jumping, soccer and basketball), in which extra body weight is undesirable, strength training actually favors larger youth and gives them a much-needed sense of physical accomplishment. Because the amount of weight lifted is positively related to body weight, heavier children can usually train with heavier weight loads than their lighter peers.
Here are some more compelling reasons why sensible resistance training benefits children:
Unfortunately, many people mistakenly believe that strength training is an inappropriate and unsafe activity for youth. Conceptually, this does not make sense. If strength training is safe and effective for your frail elderly clients, it is even better for healthy young people with full movement capacity and plenty of energy.
Indeed, no serious injury has ever been reported in any prospective study on youth strength training. Not only is strength training safe for kids, but it may actually help reduce the number of injuries they sustain during other physical activities. According to the American College of Sports Medicine (ACSM), 50 percent of preadolescent sports injuries could be prevented, in large part, by enrolling kids in youth strength and conditioning programs (ACSM l993). On a more anecdotal front, we have personally conducted regular strength training classes for children 6 to 12 years old for the past 17 years without experiencing a single injury!
Some of you may have heard that strength training can be detrimental to bone development in children, but this has never been demonstrated. Again, contrary to popular opinion, strength training has been shown to enhance bone development in kids. In a 10-month study involving 9- and 10-year-old girls, bone mineral density increased by about 6.2 percent in those who performed both strength and aerobic exercise, compared to about 1.4 percent in those who did not strength train (Morris et al. 1977).
You may also have heard that for children, calisthenics exercises are safer than strength training exercises. This is likewise untrue. Most children—especially those who are underfit and overweight—cannot complete a single pull-up, bar-dip or push-up, making these calisthenics maximum-effort exercises that result in failure. However, we have found that using resistance equipment, these same kids can adjust the weight load as necessary and are able to perform 10 to 15 controlled repetitions of every exercise.
Finally, some people question whether children can gain strength and enhance muscular development in light of their low levels of testosterone. But, if this were a true limitation, then women and elderly individuals would also be unresponsive to strength training, which is obviously not the case. In fact, studies have revealed significant increases in muscle strength and mass in preadolescent boys and girls (Faigenbaum et al. 1993; Morris et al. 1997; Pikosky et al. 2002; Westcott et al. 1995). Furthermore, research has shown that these strength training effects are relatively long-lasting (Faigenbaum et al. 1996). Although some of the strength gains are due to motor learning, children add muscle tissue through increased protein synthesis, in much the same way that adults do.
As a rule, children should do about 20 minutes of well-designed and carefully supervised strength training (ideally sandwiched between 10 minutes of warm-up and cool-down activities) 2 or 3 nonconsecutive days each week.
Although optimal strength training protocols for adults and children are similar in certain ways, we have discovered some notable differences, especially in the area of sets and repetitions. The following sections describe the specific guidelines and exercises we have used in our kids strength training programs.
We have obtained our best research results using the DeLorme-Watkins strength training protocol. In this protocol, the first exercise set consists of 10 repetitions performed at 50 percent of the 10-repetition maximum (10 RM) weight load; the second set consists of 10 repetitions performed at 75 percent of the 10 RM weight load; and the final set consists of as many repetitions as possible with the 10 RM weight load. When a child can complete 15 repetitions, a higher 10 RM weight load is determined and the training protocol repeats. During 8 weeks of training, the 10-year-old boys and girls who followed this program increased their overall muscle strength (five exercises) by 74 percent, compared to 13 percent for the matched control subjects (Faigenbaum et al. 1993).
A follow-up study using the more challenging Berger strength training protocol showed less success. Children (also 10-year-olds) who performed three sets of six repetitions, each using the six-repetition maximum (6 RM) weight load, saw less improvement (47 percent strength gain) over an 8-week training period than those who used the DeLorme-Watkins protocol (Faigenbaum et al. 1996). These comparative results suggested that three high-effort sets of each exercise may not be necessary for strength development in preadolescents.
Owing to the time constraints of our 1-hour training sessions, our youth strength studies over the past 6 years have incorporated one set of each resistance exercise—with excellent results and no injuries.
Because the children in the research cited above appeared to respond better to higher-repetition training, we decided to conduct a study that compared different numbers of repetitions (Faigenbaum et al. 1999). Half of the children performed one exercise set to muscle fatigue using six to eight repetitions, and the other half performed one exercise set to muscle fatigue using 13 to 15 repetitions. The average strength improvement was 18 percent for the lower-repetition group and 29 percent for the higher-repetition group. These results were consistent with our previous studies and supported higher-repetition strength training protocols for preadolescents.
If children perform more than one set of each exercise, we recommend that they rest for approximately 2 minutes between sets.
When it comes to training frequency, we have observed similar strength gains in children whether they exercise 2 or 3 nonconsecutive days per week; this is consistent with our research on adult trainees (Westcott & Guy 1996). We recommend beginning with two strength workouts per week, performed on nonconsecutive days, with the option of adding a third session if youngsters desire it.
Although there are no hard-and-fast rules for increasing exercise resistance for kids, we follow a double-progressive protocol to avoid doing too much too soon. For example, we begin with a weight load that the child in question can lift for 10 to 13 repetitions. When the youngster can complete 15 repetitions, we increase the resistance by as little as possible (typically 1 to 5 pounds) and by no more than 5 percent (e.g., from 20 to 21 pounds, or 40 to 42 pounds). The child trains with the higher weight load until he or she can complete 15 repetitions, and again we increase the resistance slightly (no more than 5 percent).
The key to successful kids strength training is gradual progression, which facilitates safe workouts that are both challenging and reinforcing.
Training technique encompasses movement speed, movement range, correct breathing and proper posture during the exercise performance. We prefer controlled movement speed, allowing about 2 seconds for each lifting movement and about 2 seconds for each lowering movement. In this manner, children can complete one set of 15 repetitions in approximately 60 seconds, which represents an appropriate bout of high-effort, anaerobic exercise.
We generally recommend full movement range on simple exercises (e.g., biceps curl and triceps extension). However, to reduce the risk of injury, we prefer moderate movement range on complex exercises that require excessively stretched starting positions (e.g., leg press and chest press). For example, during the leg press, children’s knees should not flex more than 90 degrees.
Correct breathing technique requires exhaling during the lifting movement (concentric muscle action) and inhaling during the lowering movement (eccentric muscle action). Proper posture—which facilitates correct breathing and exercise performance—is typically characterized by standing or sitting tall; keeping the head up, shoulders square, torso erect and hips level; and avoiding twisting, turning and squirming actions.
Our experience indicates that preadolescents should perform six to 12 different strength exercises each training session. The exercise program should address all of the major muscle groups, including the quadriceps, hamstrings, gluteals, spinal erectors, abdominals, pectoralis major, latissimus dorsi, deltoids, upper trapezius, biceps and triceps. We recommend that you progress from large to small muscle groups in the same way you would for adults. The exercises described on pages 40-42 are the specific ones we use in our youth strength training programs and are shown in the order of progression.
As for equipment preferences, we have observed the same strength improvements whether our young subjects used free weights (dumbbells) or resistance machines (either youth-sized or adult-sized) (Westcott et al. 1995; Faigenbaum et al. 1996).
YOUTH-SIZED RESISTANCE MACHINE EXERCISES FOR KIDS
If children have access to youth-sized resistance machines, we recommend the exercises on page 40. Typically, youth-sized resistance machines are configured with smaller frames and shorter lever arms.
ADULT-SIZED RESISTANCE MACHINE EXERCISES FOR KIDS
Although youth-sized resistance equipment is best suited for smaller-framed boys and girls, most preadolescents can train safely and productively on adult-sized machines that use linear (pushing or pulling) movements. The adult-sized resistance machine exercises listed on page 41 are appropriate for most boys and girls.
FREE-WEIGHT EXERCISES FOR KIDS
Resistance machines are particularly useful for overweight children because the equipment supports their body weight. However, if resistance machines are not available, children can exercise safely and effectively using free weights (dumbbells rather than barbells) or elastic bands, as long as they comply with the strength training guidelines outlined in this article. (One resistance exercise we feel children should not perform is the barbell squat, which places excessive loading forces directly on a child’s developing spinal column.)
For gradual progression in dumbbell exercises, children may use 1-pound magnetic add-on weights. Consider the dumbbell exercises listed below as alternatives to machine strength training.
Without question, the most important aspect of a safe and successful kids strength training program is qualified adult supervision throughout each exercise session. Proper instruction, including appropriate performance feedback and positive reinforcement, is essential to injury prevention, participant satisfaction and the development of children’s competence and confidence in this activity.
We are happy to report that the hundreds of boys and girls who have participated in our strength training programs over the past 17 years have had a 90 percent compliance rate and a 0 percent injury rate, which we attribute to proper supervision. When properly designed and carefully conducted, strength training may very well be the safest and most physiologically beneficial activity children can do.
Muscles are the engines that “run” the body, and it is essential to maintain those engines to steer an active lifestyle. In the past, childhood was the most active time in people’s lives, but today’s children tend to be preoccupied with inactive pastimes and few do enough resistance exercise to develop strong musculoskeletal systems.
Fortunately, there is a simple solution. Research confirms that sensible strength training will help children look better, feel better and function better, as well as develop an activity pattern that should serve them well throughout their lives. With their engines revved up, your young charges will be on the right track for a lifetime of activity and good health.
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