Although the influence of the series elastic element of the muscle–tendon unit on jump performance has been investigated, the corresponding effect of the parallel elastic element remains unclear. This study examined the relationship between the resting calf muscle stiffness and drop jump performance. Twenty-four healthy men participated in this study. The shear moduli of the medial gastrocnemius and the soleus were measured at rest as an index of muscle stiffness using ultrasound shear wave elastography. The participants performed drop jumps from a 15 cm high box. The Spearman rank correlation coefficient was used to examine the relationships between shear moduli of the muscles and drop jump performance. The medial gastrocnemius shear modulus showed a significant correlation with the drop jump index (jump height/contact time) (r = 0.414, P = 0.044) and jump height (r = 0.411, P = 0.046), but not with contact time (P > 0.05). The soleus shear modulus did not correlate with these jump parameters (P > 0.05). These results suggest that the resting medial gastrocnemius stiffness can be considered as one of the factors that influence drop jump performance. Therefore, increase in resting muscle stiffness should enhance explosive athletic performance in training regimens.

尽管已经研究了肌腱单元的串联弹性元件对跳跃性能的影响，但平行弹性元件的相应作用仍不清楚。这项研究检查了休息小腿肌肉的刚度和下降跳性能之间的关系。24名健康男性参加了这项研究。静止时腓肠肌和比目鱼肌的剪切模量是使用超声剪切波弹性成像法测量的，作为肌肉僵硬的指标。参与者从15厘米高的盒子中进行了跳跳动作。Spearman等级相关系数用于检验肌肉的剪切模量与跳跳性能之间的关系。腓肠肌内侧剪切模量与下降跳跃指数（跳跃高度/接触时间）呈显着相关性（r = 0.414，P  = 0.044）和跳跃高度（r = 0.411，P  = 0.046），但没有接触时间（P  > 0.05）。比目鱼剪切模量与这些跳跃参数不相关（P  > 0.05）。这些结果表明，静止的腓肠肌内侧僵硬可以被认为是影响液滴跳跃性能的因素之一。因此，增加静息肌肉的刚度应该在训练方案中增强爆发性运动表现。