To obtain basic data on the imbalance between physique and physical development in children in recent years, as well as the relationship between obesity and physical strength, this study examined the relationship between body composition and physical strength/motor ability in children. We then tried to verify physical and motor abilities according to the morphological qualities and differences in physical and motor abilities with children classified by degree of obesity or leanness derived from BMI. The subjects were 97 boys and 92 girls at a nursery school in Gifu Prefecture, Japan. The items measured for physique and body composition were height, weight, BMI, muscle mass, body fat percentage, and amount of body fat. Bone density was calculated from speed of sound (SOS) and osteo-sono assessment index (OSI) from ultrasound propagation velocity and transmission index. The items measured for motor performance were 20 m dash, standing long jump, tennis ball throw, repetitive sideways jump, one-legged jump, and chin-ups.
A partial correlation analysis of physique/body composition and physical strength/motor ability was conducted, but no notable correlation was found between body composition and physical strength/motor ability. From this it is conjectured that physique and body composition have little effect on physical strength and motor ability in early childhood. Next, the children were classified as obese, average, or lean based on BMI, and a comparison was made between the groups in physical strength and motor ability. Among boys significant differences were seen in the 20 m dash, standing long jump, tennis ball throw, repetitive sideways jump, and one-legged jump. Among girls, no significant differences were seen in any of the items. A comparison of physical strength and motor ability by differences in morphological qualities revealed no significant differences in any item in either girls or boys. Thus, because congenitally determined factors are strong in the attainment of physical growth and development in early childhood, the effect of differences in morphological qualities on physical strength and motor ability is assumed to be small in early childhood.
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