Influence of lifestyle-related factors on the development of musculo-skeletal system of school-aged children

Abstract

　In order to investigate the causes of bone fracture and hypo-function of locomotorium, especially musculo-skeletal system, which are frequently observed for school-age children in recent years. focusing on bone and muscle, major organs of locomotion, bone density and body composition such as muscle distribution and body fat percentage were measured with use of an ultrasound bone densitometer (AOS-100SA), InBody430 and locomo-check tests, and the possible association of the lifestyle-related factors were examined.

　Observations were made on the total of 167 school children of 4th, 5th and 6th graders (54 males and 113 females). The height, the weight and the blood pressure were in the range of the standard value for all children. The distribution of the body types of thin, average and overweight were 15.6%, 75.0% and 9.4% for male, and 16.1%, 66.6% and 17.3% for female, respectively. The bone density (OSI) for 4th, 5th and 6th graders were 2.27, 2.23 and 2.55 for male, and 2.37, 2.38 and 2.43 for female, respectively, all of which were within normal ranges and increased as the grade was advanced. Among 126 children who were tested for their locomotion ability (locomo-checks), locomotory hypo-function was suspected for 62.5% male 44.8% female children, and the abilities of forward bending and squatting down were low in particular. By the consideration in 29 children who answered on the lifestyle habits questionnaire, the bone density (OSI) and the bone Z score showed significant positive correlation with the present frequency of physical activity (r=0.398*/r=0.435*), amounts of exercise (/r=0.407*), and the frequency of vegetable intake (r=0.411*/r=0.400*), and the bone SOS showed the positive correlation with the frequency of seaweed intake (r=0.438*). The bone density (OSI) and the bone SOS showed positive correlation with the muscle mass (r=0.478*), and negative correlation with the body fat percentage (r=-0.404*). The bone SOS was observed higher for those children doing more sports in a spare time, with more times of going to private tutoring school, and with shorter sleeping hours (r=0.736**). As the total score of the locomo-check tests was higher, the body fat percentages of the trunk and the limbs were higher. The body fat percentage of the limbs was lower as the muscle development rates of the both legs and the right arm became higher (r=-0.414*-r=0.676**). Those children with higher bone density (OSI) and higher bone BUA were observed to less likely to catch a cold (r=-0.43*/ r=-0.532**), and there exists a park in neighborhood as an environmental factor.

　Further studies are planned with increased number of cases, and evaluation of the locomotory system function will be made from the multilateral view points.