Physical strength in boys with different levels of fat accumulation and BMI: report on South Korean junior high school boys.

The figpurpose of this study was to investigate the evaluation of differences in morphological qualities in physical strength of South Korean junior high school boys. The subjects were 201 first-year junior high school boys (13.6 +/- 0.3 years, 59.0 +/- 12.8 kg, 163.1 +/- 7.4 cm, in whom height, weight, BMI, fat mass, body fat percentage and soft lean mass were measured. Items of physical strength measured were the sit and reach, 20-m shuttle run, push-ups, and sit-ups. Morphological quality was judged from two aspects, a BMI evaluation of obesity or leanness and an evaluation of the level of fat accumulation derived from regression polynomials of body fat percentage against BMI. The subjects were classified into 9 groups according to differences in morphological quality. Of the physical measurement items, boys with underdevelopment of fat in the BMI slim and normal groups showed superior results in the 20-m shuttle run, push-ups and sit-ups. In contrast, boys with overdevelopment of fat in the BMI fatty group showed significantly poorer results in these items. Meanwhile, boys with underdevelopment of fat in the BMI fatty group showed a level comparable to boys in the BMI normal and excessive fat groups in the 20-m shuttle run; boys with normal and excessive fat in the BMI normal group and boys with excessive fat in the BMI slim group in push-ups; and boys with underdevelopment of fat in the BMI slim group in sit-ups. Performance in these measurements was evaluated in detail for boys with different morphological qualities, and multiple considerations from the two aspects of physique and physical composition may be necessary to evaluate the physical strength of students in each grade.