Maloney Sean J, Richards Joanna, Fletcher Iain M
1 University of Bedfordshire.
J Appl Biomech. 2018 Jun 1;34(3):199-204. doi: 10.1123/jab.2017-0094. Epub 2018 May 25.
This study sought to compare vertical stiffness during bilateral and unilateral drop jumping. Specifically, the intersession reliabilities and force-deformation profiles associated with each task were to be examined. On 3 occasions, following familiarization, 14 healthy males (age: 22 [2] y; height: 1.77 [0.08] m; and body mass: 73.5 [8.0] kg) performed 3 bilateral, left leg and right leg drop jumps. All jumps were performed from a drop height of 0.18 m on to a dual force plate system. Vertical stiffness was calculated as the ratio of peak ground reaction force (GRF) to the peak center of mass (COM) displacement. Unilateral drop jumping was associated with higher GRF and greater COM displacement (both Ps < .001), but vertical stiffness was not different between tasks when considering individual limbs (P = .98). A coefficient of variation of 14.6% was observed for bilateral vertical stiffness during bilateral drop jumping; values of 6.7% and 7.6% were observed for left and right limb vertical stiffness during unilateral drop jumping. These findings suggest that unilateral drop jumps may exhibit greater reliability than bilateral drop jumps while eliciting similar vertical stiffness. It is also apparent that higher GRFs during unilateral drop jumping are mitigated by increased COM displacement.
本研究旨在比较双侧和单侧下蹲跳时的垂直刚度。具体而言，要研究与每个任务相关的组内信度和力-变形曲线。14名健康男性（年龄：22[2]岁；身高：1.77[0.08]米；体重：73.5[8.0]千克）在熟悉练习后，分3次进行了3次双侧、左腿和右腿下蹲跳。所有跳跃均从0.18米的下落高度跳至双测力台系统上。垂直刚度计算为地面反作用力峰值（GRF）与质心（COM）位移峰值之比。单侧下蹲跳与更高的GRF和更大的COM位移相关（P值均<0.001），但在考虑单个肢体时，各任务之间的垂直刚度并无差异（P = 0.98）。双侧下蹲跳时双侧垂直刚度的变异系数为14.6%；单侧下蹲跳时左腿和右腿垂直刚度的值分别为6.7%和7.6%。这些发现表明，单侧下蹲跳在产生相似垂直刚度的同时，可能比双侧下蹲跳表现出更高的信度。同样明显的是，单侧下蹲跳时较高的GRF会因COM位移增加而得到缓解。
