Avela J, Santos P M, Komi P V
Department of Biology of Physical Activity, University of Jyväskylä, Finland.
Eur J Appl Physiol Occup Physiol. 1996;72(5-6):553-62. doi: 10.1007/BF00242290.
The neuromuscular characteristics of the triceps surae and vastus lateralis muscles and interactions between the pre-activation of these muscles and the muscle output itself during ground contact were investigated during various types of stretch-shortening cycle muscle loading. The loading of the muscles was effected by using three different types of drop jump exercise. These jumps allowed separate modifications of the loading of the leg extensor muscles by changing the velocity of the centre of gravity (CG) or by changing directly the body mass, which was also affected by changing artificially the acceleration of the CG. It was found that the eccentric peak angular velocity of the ankle joint was related to the various precontact and eccentric parameters in all the different types of jumping exercise. The correlations were higher for the gastrocnemius muscle (P < 0.001) than for the soleus muscle (n.s., P < 0.01). In all the experimental conditions, the pre-activation of the measured muscles started well before the impact of contact with the ground. However, the duration of the pre-activation phase depended on the type of stretch exercise. The results would suggest a clear interaction between the pre-activation of the muscles and that part of the muscle output which is effected by the segmental stretch reflex system. The control mechanism of the pre-activation itself appears to be multiple in character. It seems reasonable to assume that the pre-activation is preprogrammed, but which can, however, be modified by proprioceptive, vestibular and visual inputs. Thus, the possibility of conscious modification of the expected muscle load must be considered.
在各种类型的拉长-缩短周期肌肉负荷过程中，研究了小腿三头肌和股外侧肌的神经肌肉特征，以及这些肌肉在着地过程中的预激活与肌肉输出本身之间的相互作用。肌肉负荷通过三种不同类型的纵跳练习来实现。这些跳跃通过改变重心（CG）的速度或直接改变体重来分别改变腿部伸肌的负荷，而体重的改变也受到人为改变CG加速度的影响。研究发现，在所有不同类型的跳跃练习中，踝关节的离心峰值角速度与各种预接触和离心参数有关。腓肠肌的相关性（P < 0.001）高于比目鱼肌（无显著性差异，P < 0.01）。在所有实验条件下，被测肌肉的预激活在接触地面之前就已经开始。然而，预激活阶段的持续时间取决于拉伸练习的类型。结果表明，肌肉的预激活与由节段性牵张反射系统影响的那部分肌肉输出之间存在明显的相互作用。预激活本身的控制机制似乎具有多重性。可以合理地假设预激活是预先编程的，但它可以通过本体感觉、前庭和视觉输入进行修改。因此，必须考虑有意识地改变预期肌肉负荷的可能性。
