Kurokawa Sadao, Fukunaga Tetsuo, Nagano Akinori, Fukashiro Senshi
Laboratory of Sports Sciences, Joshibi University of Art and Design, Suginami, Tokyo, Japan.
J Appl Physiol (1985). 2003 Dec;95(6):2306-14. doi: 10.1152/japplphysiol.00219.2003. Epub 2003 Jul 18.
Behavior of fascicles and tendinous structures of the m. gastrocnemius medialis (MG) was quantitatively examined during human jumping in vivo. Eight male subjects performed maximal-effort counter movement jumping (CMJ) motions. Kinematic and kinetic data were obtained using a high-speed camera and a force platform. Behavior of fascicles and tendinous structures was determined using ultrasonography and electromyography. Although the muscle-tendon complex (MTC) shortened by only 1.6% during the downward phase of the counter movement, fascicles shortened as much as 10.4%. This shortening of fascicles caused elongation of tendinous structures by 2.2%. Although the MTC remained at almost constant length during the upward-I phase (-250 to -100 ms before toe-off), fascicles shortened by 19.2% of the initial length with an elongation of tendinous structures by 4.4%. The MTC shortened rapidly by 5.3% of the initial length during the upward-II phase (-100 to 0 ms), whereas fascicles shortened slightly during the first half of this phase and contracted in a quasi-isometric manner during the latter half of this phase. These findings implied that elastic energy was stored in tendinous structures throughout the latter half of the downward phase (1.0 J) and upward-I phase (5.6 J), which was thereafter rapidly released during the upward-II phase (3.8 J). It was found that muscle fibers of the MG were not stretched during counter movement; therefore, stretch reflex and potentiation of the contractile component of the MG might not contribute to the work enhancement in CMJ. It was suggested that the interaction between fascicles and tendinous structures was essential in a generation of higher joint power during the late push-off phase. This behavior of the MTC of the MG in CMJ was quite similar to what was observed in squat jumping performed without counter movement.
在人体活体跳跃过程中，对内侧腓肠肌（MG）的肌束和肌腱结构的行为进行了定量研究。八名男性受试者进行了最大努力的反向运动跳跃（CMJ）动作。使用高速摄像机和力平台获取运动学和动力学数据。通过超声检查和肌电图确定肌束和肌腱结构的行为。尽管在反向运动的下降阶段，肌肉 - 肌腱复合体（MTC）仅缩短了1.6%，但肌束缩短了多达10.4%。肌束的这种缩短导致肌腱结构伸长了2.2%。尽管在向上 - I阶段（离地前 - 250至 - 100毫秒）MTC几乎保持恒定长度，但肌束缩短了初始长度的19.2%，同时肌腱结构伸长了4.4%。在向上 - II阶段（ - 100至0毫秒），MTC迅速缩短了初始长度的5.3%，而肌束在该阶段的前半部分略有缩短，在后半部分以准等长方式收缩。这些发现表明，弹性能量在下降阶段的后半段（1.0焦耳）和向上 - I阶段（5.6焦耳）存储在肌腱结构中，随后在向上 - II阶段迅速释放（3.8焦耳）。研究发现，在反向运动过程中，MG的肌纤维没有被拉伸；因此，MG的牵张反射和收缩成分的增强可能对CMJ中的功增强没有贡献。有人提出，在蹬离后期产生更高的关节功率时，肌束和肌腱结构之间的相互作用至关重要。MG在CMJ中的MTC的这种行为与在无反向运动的深蹲跳跃中观察到的行为非常相似。
