其他摘要：The difference in force exerted by the same muscles under the different conditions has been studied by many investigators. According to those reports, the maximal eccentric force was more than the isometric force. The present study was undertaken to investigate the strength of flexor muscles of the forearm exerted under isometric and eccentric conditions, and to compare the isometric strength and eccentric strength in relation to age cross-sectionally. 2,221 healthy boys and girls, aged from 4 to 20 years, participated in the measurements. The subjects were asked to exert his maximal strength at the right angle of the elbow joint in sitting position. The subject grasped the belt which was connected through the metal cord to the dynamometer. The dynamometer was constructed of semiconductive strain gauge. When the eccentric strength was measured, the dynamometer was towed until the subject could not hold his elbow joint at the right angle. When the isometric strength was measured, the dynamometer was fastened to the wall. The results obtained are as follows; (1) Up to ten years of age, there is no difference in muscle strength between boys and girls, and thereafter muscle strength increases much faster in boys than in girls. (2) Eccentric strength is always larger than isometric strength. But the ratio of eccentric strength to isometric strength decreases as the age grows from 4 to 11 years of age, and thereafter it becomes an approximately constant value (110% for boys and 120% for girls).
