- 一般社団法人 日本体育学会
- 体育学研究 (ISSN:04846710)
- pp.17129, (Released:2018-08-06)
The purpose of this study was to evaluate the multistep drop jump (DJ) test in elite jumpers according to changes in test performance, ground reaction force, and lower limb joint kinetics with changes in drop height. Male jumpers (n=10) performed a DJ from 4 drop heights (0.3, 0.6, 0.9, and 1.2 m). The DJ-index was calculated by dividing the jump height by the contact time. The rate of change of the DJ-index (a/b) was the slope/intercept of the regression line (Y = aX+ b) derived from 4 values of the DJ-index for each subject. Jump motions in the sagittal plane and ground reaction force data were recorded using a high-speed camera and force platform, respectively. The DJ-index was lower at 1.2 m than at other drop heights. The contact time increased along with the drop height. There was no significant difference in jump height between the drop heights. The amount of negative work by 3 lower extremity joints increased with increasing drop height. The jump events performance (IAAF Score) and DJ-index at each drop height only showed a significant correlation at 1.2 m. The correlation between IAAF score and a/b was significant between these variables. According to individual characteristics, increased drop heights were associated with different patterns of change in the DJ index. Therefore, subjects were grouped according to characteristics using a/b as an index. Sub.A, who had the highest jump-event performance in the study, had participated in international meetings, and had won a medal at the World Junior Championships. The DJ-index for this subject at 0.3 m was close to the mean value, but at 1.2 m was highest among all the subjects. In contrast, the DJ-index for Sub.C at 0.3 m was highest among the subjects. However, the DJ-index decreased greatly with an increase from 0.3 m to 1.2 m. Therefore, to evaluate the performance of jumpers, it is important to use a varied range of heights, including a higher drop height (approximately 1.2 m), focusing on the rate of change with increasing drop height.