Effects of physical activities and eating behavior on the body composition and bone density in the youth (A study in elementary school and junior high school students)

2003 Fiscal Year Final Research Report Summary

• Project/Area Number: 13680043
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: 体育学
• Research Institution: Siebold University of Nagasaki
• Principal Investigator: TSUNAWAKE Noriaki Siebold University of Nagasaki, Faculty of Nursing and Nutrition, Professor, 看護栄養学部, 教授 (10172040)
• Co-Investigator(Kenkyū-buntansha): MURAKI Satishi Kyushu University, Faculty of Design, Associate Professor, 大学院・芸術工学研究院人間生活システム部門, 助教授 (70300473) ; MUTO Keiko Siebold University of Nagasaki, Faculty of Nursing and Nutrition, Associate Professor, 看護栄養学部, 助教授 (70290616) ; SAIMEI Mari Siebold University of Nagasaki, Faculty of Nursing and Nutrition, Professor, 看護栄養学部, 教授 (50178521)
• Project Period (FY): 2001 – 2003
• Keywords: youth / growth and development / body composition / bone density / physical fitness / eating behavior

Research Abstract

The elementary school and junior high school periods are a time of marked morphological growth of the body, and the development of physical fitness, body composition, and bone density in this period greatly affects not only the health of this period but also the state of health in the subsequent periods.
In this study, we measured the body composition (by bioelectrical impedance analysis), bone, density (stiffness index required by ultrasound bone densitometer), and exercise abilities, and investigated the state of physical activities and nutrition in elementary school and junior high school students to evaluate characteristics of the body composition and bone density in the youth and their sex differences, relationships between their development and fitness, their relationships with the state of participation in sports activities, and their relationship with the state of physical fitness and nutrition, and to propose suitable physical activities and eating behavior in the contemporary living environment
Major findings obtained in this study are summarized as follows.
1. Differences in the body composition between males and females began to increase after the 6th grade as the lean body weight increased in males and fat increased in females.
2. The lean body mass and bone density were closely related in both males and females.
3. The lean body mass and bone density were both closely related to exercise abilities.
4. The promotive effect of exercise on the increase in bone density was observed clearly after about the 7th grade in males and after about the 6th grade in females.
5. The exercise habit was closely related to the development of elements of exercise abilities such as the muscle strength, endurance capacity, and muscle power.
6. In junior high school students, an unbalanced diet such as excessive intakes of sweets and soft drinks and avoidance of grains/beans and seaweed were noted.
These results suggest that poor eating habits are widespread, and that awareness of the importance of diet-exercise is inadequate. Improvement of nutritional education and exercise is considered to be urgently needed to promote sound development of the youth.