Taiikugaku kenkyu (Japan Journal of Physical Education, Health and Sport Sciences)
Online ISSN : 1881-7718
Print ISSN : 0484-6710
ISSN-L : 0484-6710
The specificity of leg strength and power in several sport athletes
Koji ZushiKaoru TakamatsuTakayoshi Kotoh
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1993 Volume 38 Issue 4 Pages 265-278

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Abstract

This study clarified the specificity of leg strength and power in several sport athletes. To accomplish this purpose, a new physical fitness test was developed to evaluate the capacity for the ballistic and stretch-shortening cycle (SSC) movements. 1. The drop jump (DJ), a typical SSC movement was used in this test. A few experiments were performed to determine the best dropping height and jumping technique of DJ in 10 college male athletes. These results showed the best method of DJ was rebound DJ with small angular displacement of the knee from 0.3 m beause of appearing the shortest contact time and the longest air time, and being ballistic and safe movement. 2. Average force[F_&ltindex&gt ={(t_a)/2 + (2・h_d/g)^&lt1/2&gt}/(t_c + 1)], average Power[P_&ltindex&gt ={g・(t_a/2)^2 - 2・h_d}/ (2・t_c)]and the capacity to jump higher within shorter contact time[DJ_&ltindex&gt = (1/8・g・t_a^2) /t_c]are calculated by using contact time (t_c) , air time (t_a) and dropping height (h_d) of DJ, and g (9.81 m/s^2). Interrelationships between DJ_&ltindex&gt F_&ltindex&gt, P_&ltindex&gt t_c and t_a were examined in 93 male athletes of 14 sport events. These results showed the best index was DJ_&ltindex&gt because of reflecting both F_&ltindex&gt and P_&ltindex&gt, and t_c and t_a. 3. The specificity of leg strength and power was investigated by comparing with DJ_&ltindex&gt height of counter movement jump (CMJ-H) and maximum strength exerted by squat posture at 90°of knee angle (S-MAX) in 93 male athletes of 14 sport events. This result showed all sport athletes were grouped into A, B and C type. Jumper and sprinter, gymnast and kendo atheletes belonged to A type which showed the character of large in order of DJ_&ltindex&gt, CMJ-H and S-MAX. Skater, ski jumper and swimmer belonged to B type which showed contrary character of A type. Ball game player and long distance runner belonged to C type which did not show difference among them. But excellent players for jump and footwork in ball games showed the same character as jumper and sprinter. These results lead to the conclusion that we should evaluate not only the general leg strength and power but also the capacity for the ballistic and SSC movement by measuring DJ_&ltindex&gt when coaches scout for sport talents and athletes practice the training according to specificity of strength and power. It should also be added that DJ_&ltindex&gt is a practical index which can be simply and exactly measured by using matswitch.

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© 1993 Japan Society of Physical Education, Health and Sport Sciences
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