Yoon S, Tauchi K, Takamatsu K
Department of Physical Education, Korea University, Seongbuk-gu, Seoul, Korea.
Int J Sports Med. 2007 Jan;28(1):66-71. doi: 10.1055/s-2006-923903. Epub 2006 Oct 6.
The purposes of this study were to investigate firstly, the ankle joint stiffness during the eccentric phase in rebound jumps, and secondly, the effect of ankle joint stiffness during the eccentric phase on ankle joint torque at midpoint. Nine active males executed rebound drop jumps from a height of 30 cm (RDJ30) and 50 cm (RDJ50), and 5-repetition rebound jumps (5RJ). Force plate data, limb position and electromyogram (EMG) of the medial head of gastrocnemius (GAS), soleus (SOL), and tibialis anterior (TA) muscles were recorded simultaneously during all jumps. When compared with RDJ30 and RDJ50, 5RJ displayed significantly higher jumping height, ankle joint torque at midpoint, ankle joint stiffness during the eccentric phase, and integrated EMG (IEMG) of GAS and SOL. Furthermore, 5RJ displayed significantly lower contact time and IEMG of TA than RDJ30 and RDJ50 did. The ankle joint torque at midpoint showed a significant positive correlation with jumping height but a significant negative correlation with contact time in rebound jumps. There was a significant positive correlation between the ankle joint stiffness during the eccentric phase and ankle joint torque at midpoint in rebound jumps. These results suggested that for the rebound jumps to be effective, it may be important to enhance the ankle joint torque at midpoint by greater ankle joint stiffness during the eccentric phase. These results also suggested that compared to 5RJ, RDJ30 and RDJ50 may reduce ankle joint stiffness in order to protect the tendomuscular system from the stretch load. However, ankle joint stiffness is possibly increased in 5RJ because the restraint to defend the tendomuscular system is reduced by prediction or adaptation to the stretch load because it is a continuous jump.
本研究的目的，一是调查在反弹跳的离心阶段踝关节的僵硬度，二是研究离心阶段踝关节僵硬度对中点处踝关节扭矩的影响。九名活跃男性分别从30厘米（RDJ30）和50厘米（RDJ50）的高度进行反弹下落跳，以及5次重复的反弹跳（5RJ）。在所有跳跃过程中，同时记录力台数据、肢体位置以及腓肠肌内侧头（GAS）、比目鱼肌（SOL）和胫骨前肌（TA）的肌电图（EMG）。与RDJ30和RDJ50相比，5RJ的跳跃高度、中点处的踝关节扭矩、离心阶段的踝关节僵硬度以及GAS和SOL的积分肌电图（IEMG）均显著更高。此外，与RDJ30和RDJ50相比，5RJ的接触时间和TA的IEMG显著更低。在反弹跳中，中点处的踝关节扭矩与跳跃高度呈显著正相关，但与接触时间呈显著负相关。在反弹跳中，离心阶段的踝关节僵硬度与中点处的踝关节扭矩之间存在显著正相关。这些结果表明，对于有效的反弹跳而言，在离心阶段通过更大的踝关节僵硬度来增强中点处的踝关节扭矩可能很重要。这些结果还表明，与5RJ相比，RDJ30和RDJ50可能会降低踝关节僵硬度以保护肌腱肌肉系统免受拉伸负荷。然而，在5RJ中踝关节僵硬度可能会增加，因为它是连续跳跃，对拉伸负荷的预测或适应减少了对肌腱肌肉系统的保护作用。
