BODY-COMPOSITION MEASUREMENT BY ELECTRICAL BIOIMPEDANCE METHOD TO ESTABLISH THE EFFECT OF DAILY PHYSICAL-TRAINING IN ADOLESCENTS

As part of an ongoing study on the effect of daily physical training o n adolescents, body composition (percentage fat) was measured using th e electrical bio-impedance method in a sample of Japanese students age d 15 years (77 sedentary males, 137 active males, 66 sedentary females and 54 active females), who were selected on the basis of their answe rs in a questionnaire about physical activity in a cardiac study invol ving 227.361 high school students. Subjects were divided into 4 weight categories (underweight, normal weight, overweight and severe overwei ght) using an obesity index. ECG and ultrasound cardiography (UCG) wer e used for all subjects to measure their left ventricular mass (LVM), which was taken as an indicator of the effect of training. Among the 4 weight category groups, a significant difference in the percentage of fat between sedentary and active subjects was found in the normal wei ght category of males. Correlation between the percentage of fat and t he obesity index was significant in both sedentary and active subjects of both the genders, but correlation coefficients were lower for acti ve subjects than for sedentary ones. The percentage of fat tended to b e very low in subjects with increased LVM. Additionally, a significant difference in the amount of fat was found between runners and soccer players in active males with normal weight. These results suggest that there were differing degrees of the effect of training on reducing bo dy fat and that this effect is most notable in males with normal weigh t. Running was also found to be especially more effective in reducing body fat than playing soccer. From our results, it could be concluded that this method is useful clinically in establishing even slight chan ges of body composition depending on physical activity in adolescents.