Physical Education and Sports Science Academic Group, National Institute of Education, Nanyang Technological University , Singapore, Singapore.
Sports Science and Engineering Laboratory, Xtep (China) Co Ltd , Xiamen, China.
J Sports Sci. 2020 Jul;38(14):1605-1614. doi: 10.1080/02640414.2020.1752535. Epub 2020 Apr 14.
This study investigated the between-limb asymmetry in kinetic and temporal characteristics during bilateral plyometric drop jumps from different heights. Seventeen male basketball players performed drop jumps from 3 heights on two platforms in randomized orders. Vertical ground reaction force data were analysed with respect to the lead limb (i.e. the limb stepping off the raised platform first) and trail limb. Peak forces and loading rates of each limb were calculated. The absolute time differential between the two limbs at initial ground contact and takeoff were determined. The frequency of symmetrical landing and taking off with "both limbs together" were counted using 3 time windows. Results showed that the lead limb displayed higher peak forces and loading rates than the trail limb across all heights (p <.05). As drop height increased, the absolute time differentials decreased at initial ground contact (p <.001) but increased at takeoff (p =.035). The greater the preset time window, the more landings and takeoffs were classified as bilaterally symmetrical. In conclusion, higher drop heights allowed subjects to become more bilaterally symmetrical in the timing of landing but this reduction in temporal asymmetry did not accompany with any reduction in kinetic asymmetry.
本研究调查了从不同高度进行双侧增强式跳落时，两腿之间动力学和时间特征的不对称性。17 名男性篮球运动员以随机顺序在两个平台上从 3 个高度进行跳落。对垂直地面反作用力数据进行了分析，涉及主导腿（即先从升高的平台上迈出的腿）和随动腿。计算了每条腿的峰值力和加载率。确定了初始触地和起跳时两条腿之间的绝对时间差。使用 3 个时间窗口计算了“双腿同时”对称着陆和起飞的频率。结果表明，在所有高度下，主导腿的峰值力和加载率都高于随动腿（p<.05）。随着下落高度的增加，初始触地时的绝对时间差减小（p<.001），但在起跳时增加（p=.035）。预设时间窗口越大，被分类为双侧对称的着陆和起飞次数就越多。总之，更高的下落高度允许受试者在着陆时的时间上变得更加双侧对称，但这种时间不对称性的减少并没有伴随着任何动力学不对称性的减少。
