The Muscle Strength of Japanese Children in Relation to Relative Growth

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The pourpose of this study was to investigate the ralative growth of muscle strength to body height as well as muscle area. Subjects were 141 boys and 130 girls from 6 to 19 years old. Maximum isometric strengths of flexion and extension at elbow and knee were measured by using Cybex II isokinetic dynamometer. Cross-sectional areas of the flexor and the extensor muscles in upper arm as well as thigh were measured by using ultrasonic apparatus. Muscle strength (Y) corresponding to either body height or muscle area (X) was plotted a double logarithmic graph to obtain the allometric equation: Y=bXa, where "a" is a growth index and "b" is a constant. Muscle strengths in relation to body heights were expressed with straight lines. Both boys and girls showed higher values in the index "a" than that expected from the assumption of geometical similarity, i.e. 3.081-3.859 for boys, 2.498-3.711 for girls, ressectively. There were linear relationships between muscle areas and strengths. In these relationships, the index "a" of the elbow extensor muscles in both boys and girls as well as the knee extensor muscles of girls were approximately same values with the theoretical ones of 1.00. However, the index "a" of the elbow flexor muscles and the knee extensor muscles in both boys and girls were higher than the expected values, i.e. 1.434-1.605. In the elbow flexor and knee extensor muscles, muscle strength per unit of muscle area tended to increase with growth of body height. These results indicate that the development of muscle strengths at elbow flexion and knee extension precede to the growth of the muscle area. The reason for this extra increase of muscle strength for muscle area at elbow flexor as well as knee extensor muscles may due to neuromuscular adaptations to the daily use of these muscles.
日本人類学会の論文

The Muscle Strength of Japanese Children in Relation to Relative Growth

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概要

日本人類学会 | 論文

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