|Budget Amount *help
¥5,500,000 (Direct Cost : ¥5,500,000)
Fiscal Year 1997 : ¥800,000 (Direct Cost : ¥800,000)
Fiscal Year 1996 : ¥700,000 (Direct Cost : ¥700,000)
Fiscal Year 1995 : ¥4,000,000 (Direct Cost : ¥4,000,000)
A longitudinal design was used to study the development of sprint performance in eight elite boys from the age of 12 to 15 years. Meanwhile, yearly measurements were performed in November for sprint speed, step frequency, step length, sprint motion, and isokinetic peak torques during knee extension and flexion. Furthermore, analyzes were tried for the support time and non-support time, the angular kinematics, and isokinetic peak torques at 60,180,300deg/s.
The results obtained were as follows :
1.At the ages of 12 and 13 years, mean values of body heigh and weight were larger for the subjects than for the normal Japanese boys. However, at the last age of 15 years, no differences were found between them. It could be, therefore, confirmed that the earlier spurt appeared for the subjects.
2.From 12 to 14 years of age, sprint speed significantly increased from 8.79m/s to 9.61m/s, and from 12 to 13 years of age, step length significantly increased 1.95m to 2.08m, while no significant increases
were observed for step frequency with age. The improvement of sprint speed, therefore, resulted from the increase of step length rather than the step frequency. The significant relationship between sprint speed and one step time suggested that it was also important to shorten support time for the improvement of sprint speed.
3.From 12 to 13 years of age, isokinetic peak torques during knee flexion (angular velocity ; 60,180,300deg/s) showed significant to increase. From 12 to 15 years of age, increases of sprint speed were significantly correlated with those of isokinetic peak torque during knee flexion at the angular valocity of 180 and 300 deg/s. Thtouth all the ages, significant partial correlations wre found between sprint speed and isokinetic peak torque during knee flexion at the angular velocity of 180and 300deg/s.
4.In spite of the fact that one subject IK showed better performance of sprint and motion than another subject NI at the age of 12 years, at the last age of 15 years the latter subjects could perform better than the former one. Such inversion was due to the larger increase of body height and weight as well as the more development of isokinetic peak torque during knee flexion for NI than for IK. Less