Study Three
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.

Study Four
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.

Study Five
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.