EMG and mechanical changes during sprint starts at different front block obliquities.
EMG and mechanical changes during sprint starts at different front block obliquities.
复制标题
冲刺期间的肌电图和机械变化从不同的前块倾斜度开始。
DOI：
10.1249/00005768-199211000-00010
复制
发表时间：
1992
影响因子：
4.1
通讯作者：
K. Hainaut
中科院分区：
文献类型：
--
作者：
N. Guissard;J. Duchateau;K. Hainaut
研究了冲刺起步期间减少的前块倾斜度对起步速度的影响。记录并分析足板表面与水平面成 70 度、50 度和 30 度角时内侧腓肠肌 (MG)、比目鱼肌 (Sol) 和股内侧肌 (VM) 的肌电 (EMG) 活动。将综合肌电图 (IEMG) 与 MG 和 Sol 中与脚和膝盖运动相关的肌肉长度变化进行比较。结果表明，显着降低前块倾斜度（P < 0.05）会增加启动速度，而不会改变推动阶段的总持续时间和整体 EMG 活动。冲刺起步表现的这种改善与小腿肌肉收缩的偏心和向心阶段 MG 的贡献增强有关。在“设定位置”，MG和Sol的初始长度与70度相比在50度和30度处增加。随后的拉伸-缩短循环得到改善，并且更有效地促进肌肉缩短的速度。此外，在偏心阶段拉长这些肌肉会拉伸肌梭，并且当块的斜率减小时，会出现有助于观察到 MG IEMG 增加的反射活动。结果表明，降低前块倾斜度会引起神经和机械变化，从而有助于提高冲刺起始速度，而不会增加推力阶段的持续时间。（摘要截断为 250 字）
The effect of decreased front block obliquity on start velocity was studied during sprint starts. The electromyographic (EMG) activity of the medial gastrocnemius (MG), the soleus (Sol), and the vastus medialis (VM) was recorded and analyzed at a 70 degrees, a 50 degrees, and a 30 degrees angle between the foot plate surface and the horizontal. Integrated EMGs (IEMG) were compared with muscle length changes in the MG and Sol in relation to foot and knee movements. The results indicate that decreasing front block obliquity significantly (P < 0.05) increases the start velocity without any change to the total duration of the pushing phase and the overall EMG activity. This improvement in sprint start performance is associated with the enhanced contribution of the MG during eccentric and concentric phases of calf muscles contraction. In the "set position" the initial length of MG and Sol is increased at 50 degrees and 30 degrees as compared with 70 degrees. The subsequent stretch-shortening cycle is improved and contributes more effectively to the speed of the muscle shortening. Moreover, lengthening these muscles during the eccentric phase stretches the muscle spindles, and the reflex activities that contribute to the observed increase in the MG IEMG, are present when the slope of the block is reduced. The results indicate that decreasing front block obliquity induces neural and mechanical modifications that contribute to increasing the sprint start velocity without any increase in the duration of the pushing phase.(ABSTRACT TRUNCATED AT 250 WORDS)