| Keywords |
BMI ; Muscle mass percentage ; Physical strength ; Polynomial regression analysis |
| Abstract |
This study examined physical strength and motor ability based on a polynomial regression analysis of muscle mass percentage against BMI in South Korean junior high school students. The subjects were 201 students in the first year of junior high school. Measurements of physique (body height and weight) and body composition (BMI, fat mass, body fat percentage, muscle mass, and muscle mass percentage) were carried out. In tests of physical strength, items from the physical fitness test were adopted for the Korean students, and sit-ups, sit-and-reach, push-ups, and 20-meter shuttle run were measured. In the polynomial regression analysis of muscle mass percentage against BMI, a high reverse correlation (r = 0.76) was shown. In normal body type classified by standard polynomial regression evaluation chart, the group with excessive development of muscle mass was superior to other groups in sit-ups, push-ups, and 20-meter shuttle run. No significant differences were shown in any items of physical strength in slim body type students, and the group with excessive development of muscle mass in the fat body type was superior to other groups in the 20-meter shuttle run. In other words, the level of qualitative accumulation of muscle did not influence physical strength in specific physiques like slim and fat body types. In the present study, BMI was newly placed as an index of a muscle mass percentage, and it was shown that physical strength could be readily understood by body fatness judgment based on BMI. |