Bobbert M F, van Ingen Schenau G J
Department of Functional Anatomy, Faculty of Human Movement Sciences, Free University of Amsterdam, The Netherlands.
J Biomech. 1988;21(3):249-62. doi: 10.1016/0021-9290(88)90175-3.
The present study was designed to investigate for vertical jumping the relationships between muscle actions, movement pattern and jumping achievement. Ten skilled jumpers performed jumps with preparatory countermovement. Ground reaction forces and cinematographic data were recorded. In addition, myoelectric activity (EMG) was recorded from seven leg muscles. EMG-signals were rectified and low-pass filtered to obtain EMG-levels. The latter, which were assumed to reflect activation levels, rose to a plateau in the sequence m. semitendinosus, long head of m. biceps femoris, m. gluteus maximus, m. vastus medialis, m. rectus femoris, m. soleus, m. gastrocnemius. It was attempted to link the EMG-pattern to the purpose of the push-off, namely to maximize the effective energy (Ey) of the mass center of the body (MCB). The term Ey designates the sum of the potential energy of MCB and the kinetic energy due to the vertical velocity of MCB. One of the requirements for maximization of Ey is that the mono-articular extensor muscles release as much energy as possible before toe-off occurs. It is argued that this requirement can only be satisfied if the vertical velocity differences between the proximal and distal ends of body segments reach their peaks in a sequence. The sequence that is realized by the pattern of muscular activation is upper body, upper legs, lower legs, feet. Another important requirement is that the mechanical energy released by the muscles is optimally used. This requirement can be satisfied by transportation of energy via the biarticular m. rectus femoris and m. gastrocnemius.
本研究旨在调查垂直跳跃中肌肉动作、运动模式与跳跃成绩之间的关系。十名熟练的跳跃者进行了带有预备反向动作的跳跃。记录了地面反作用力和摄影数据。此外，还记录了七条腿部肌肉的肌电活动（EMG）。对EMG信号进行整流和低通滤波以获得EMG水平。后者被认为反映了激活水平，其在半腱肌、股二头肌长头、臀大肌、股内侧肌、股直肌、比目鱼肌、腓肠肌的序列中上升至平稳状态。试图将EMG模式与蹬地目的联系起来，即最大化身体质心（MCB）的有效能量（Ey）。术语Ey表示MCB的势能与由于MCB垂直速度产生的动能之和。最大化Ey的要求之一是单关节伸肌在离地前尽可能多地释放能量。有人认为，只有当身体各节段近端和远端之间的垂直速度差异按顺序达到峰值时，这一要求才能得到满足。由肌肉激活模式实现的顺序是上身、大腿、小腿、足部。另一个重要要求是肌肉释放的机械能得到最佳利用。这一要求可以通过经由双关节股直肌和腓肠肌传输能量来满足。
