Comparably analysis of the difference between the performance of drop-jump and counter-movement jump

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Authors
Chen, Kai-Yun
Advisor
Issue Date
1990
Keyword
Degree
Thesis (M.A.)
Department
School of Physical Education
Other Identifiers
Abstract

In the literature, the drop jumping, one of the most popular plyometric drills, is advocated as an effective exercise to increase strength and nerve-reactive ability which will improve the vertical jumping ability. When executing drop jumps, different jumping techniques can be used. There are many reports about the influence of drop jumping by different heights or angles of knee, and hip. However there are few reports on the kinematics and muscular activity involved between drop jump techniques. In this study, two subjects executed 1) drop jumps (DJ) from a height of 30 cm and 50 cm, and 2) counter-movement jumps (CMJ). During each jumping movement, the subjects were filmed. In addition electromyographic (EMG) recordings from rectus femoris muscle were obtained and synchronized with the ground reaction force from the force platform. The results showed 1) the height of shoulder at the start of push-off was higher in DJ than in CMJ; 2) the angle of hip was significantly greater in DJ than in CMJ at the start of push-off, 3) DJ had much shorter downward time and push time than CMJ; 4) no significant difference was indicated in terms of peak to peak EMG value from rectus femoris between the two jumps; 5) Peak-to Peak EMG signal did not occur simultaneous with peak vertical force; and 6) no significant difference between the jumping height between DJ and CMJ. There are some limitations which needed to be considerated. Based on the above findings, it is suggested that the horizontal displacement or speed in drop jump might play an important role in influencing the performance. In term the jumping height, we can not say which technique was better than the other, but the author suggests further research on the biomechanics and EMG characteristics which might be influenced by multiple control of the jumping techniques.

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