As a boy, I generally liked physical education class exercises. I was not, however, fond of fitness testing day. Like 50 percent of all young people then and now, I could not chin myself and always felt embarrassed struggling to lift my body weight. It was always interesting to me that this all-out, gut-wrenching muscular effort was considered good but that any form of weight training was considered bad.
Several years later when I became the physical education teacher in that same elementary school, we did things differently. I developed an after-school weight training program for the fifth and sixth graders where the students progressively increased their muscular strength. We had no injuries, and very few program participants ever failed the chin-up test.
This took place in the early 1970s, when the prevailing misunderstanding was that youth strength training was either dangerous or worthless. Many feared that lifting weights would damage bone growth plates. Others felt strength training was useless because young muscles did not have the capacity to gain strength apart from normal growth processes.
Both assumptions have proven false. According to the National Strength and Conditioning Association, there are no documented reports of bone growth plate injury due to sensible strength training.
Several research studies have also demonstrated that boys and girls can gain muscle strength at about the same rate as adults. During the past three years, we at South Shore YMCA have completed five youth strength training studies. All were conducted by certified strength instructors over a two-month training period.
The first study (Westcott 1991) was conducted with teenage boys and girls. The training group consisted of 14 exercisers, and the control group consisted of five non-exercisers, both with an average age of 14 years. The exercise group trained three days per week for eight weeks, using eight upper and lower body machines. The participants performed one set of eight to 12 repetitions with each exercise, using slow movement speed and full movement range.
The exercise group increased their lower body strength by 63 percent and their upper body strength by 33 percent. By comparison, the non-exercise group improved their lower body strength by 8 percent and their upper body strength by 4 percent.
Both groups experienced a 3-pound increase in body weight over the two month study period. The exercisers added 4 pounds of lean weight and lost 1 pound of fat weight, whereas the non-exercisers added 2 pounds of lean weight and 1 pound of fat weight. Although the control group added lean tissue through normal growth processes, they did not improve their functional muscle strength significantly. However, the exercise group added twice as much lean tissue and made significant improvements in their functional muscle strength.
This study (Westcott 1992) involved 10 pre-adolescent boys and girls, with an average age of 10 years. All of the participants trained three days per week for eight weeks with the following machines: leg extension, leg curl, chest press, biceps curl and shoulder press. They performed one set of eight to 12 repetitions with each exercise, using slow movement speed and full movement range.
The subjects increased their chest and triceps strength by 66 percent. They also made a 4-pound improvement in their body composition by adding 3 pounds of lean weight and losing 1 pound of fat weight.
The largest study (Westcott 1993) included 57 pre-adolescent boys and girls, with an average age of 11 years. All of the participants trained three days per week for eight weeks using the leg press, compound row, bench press, torso arm and rotary torso. They performed one set of eight to 12 repetitions with each exercise, using slow movement speed and full movement range.
These exercisers increased their chest and triceps strength by 55 percent. They experienced a 6.5-pound improvement in their body composition by adding 4 pounds of lean weight and losing 2.5 pounds of fat weight.
The fourth study (Faigenbaum, Zaichkowsky, Westcott, et al, 1993) involved two groups of pre-adolescent boys and girls. The training group consisted of 14 exercisers (average age 11 years). The control group consisted of nine non-exercisers (average age 10 years). Unlike the previous studies, the exercise group trained only two days per week for eight weeks with the following machines: leg extension, leg curl, chest press, biceps curl and shoulder press. The participants performed three sets of 10 to 15 repetitions with each exercise, using slow movement speed and full movement range.
The exercise group increased their chest and triceps strength by 64 percent and their overall strength by 74 percent. Body composition changes were assessed by the sum of seven skinfold measurements. The exercise subjects experienced a 2-percent decrease in their skinfold measurements, whereas the non-exercise subjects experienced a 2-percent increase in their skinfold measurements. That is, the exercisers improved their muscle strength and body composition significantly more than the non-exercisers.
The final study (Faigenbaum, Westcott, Micheli, et al. 1996) had 15 boys and girls who did strength training and nine matched control subjects who did not exercise. The participants performed two strength training sessions per week for eight weeks on the following machines: leg extension, leg curl, chest press, biceps curl and shoulder press. They completed three sets of 6 to 8 repetitions with each exercise, using slow movement speed and full movement range.
The strength training produced a 41 percent increase in chest and triceps strength and a 53 percent increase in quadriceps strength. After another eight weeks of no strength training, the exercise group was still significantly stronger than the non-exercise group in chest and triceps strength, indicating relatively long lasting effects from the strength training program.
Discussion of Research Findings
All five studies revealed significant strength improvements in 10-to 14-year-old boys and girls following eight weeks of sensible strength training. It is interesting that the strength gains for the chest and triceps muscles were similar for the groups training with one set per exercise, three days per week (studies one, two and three) and for the groups training with three sets per exercise, twice a week (studies four and five). These findings indicate that youth strength training programs consisting of one to three sets of exercise, two to three days per week are effective for increasing muscle strength in boys and girls.
Likewise, the studies showed body composition improvements in 10-to 14-year-old boys and girls following eight weeks of sensible strength training. On the average, the young strength exercisers added 3 to 4 pounds of lean weight and lost 1 to 2.5 pounds of fat weight during the training period.
One of the most important outcomes of these five studies involving well over 100 boys and girls was the absence of any exercise-related injuries. It is therefore suggested that well-designed and well-supervised strength training programs are a safe and productive means for improving muscle strength and body composition in teen and pre-teen boys and girls.
Although the long-term benefits of youth strength training have not yet been documented, it is logical to assume that leaner and stronger youth may become leaner and stronger adults. Developing a strong musculoskeletal system during the formative years may also reduce the risk of injuries and degenerative diseases during the adult years.
The medically-based guidelines for youth strength training programs emphasize an uncrowded facility, appropriate equipment, physician clearance, qualified instructors, brief exercise periods, gradual progression, no competition and no maximum lifts. When appropriate training guidelines are observed, strength exercise is a recommended physical activity for teen and pre-teen boys and girls.
Wayne L. Westcott, Ph.D., in fitness and research director at the South Shore YMCA in Quincy, MA, and strength training consultant for numerous national organizations and publications. He is author of 10 strength training books, including Building Strength and Stamina.