Kosaka Takehiro, Kubo Keitaro
Graduate School of Integrated Science and Technology, Nagasaki University, Nagasaki, Japan.
Department of Life Science, The University of Tokyo, Meguro, Tokyo, Japan.
J Musculoskelet Neuronal Interact. 2025 Sep 1;25(3):266-275. doi: 10.22540/JMNI-25-266.
This study aimed to determine the effect of external load on the contribution of tendon lengthening during eccentric phase and tendon shortening velocity during concentric phase in stretch-shortening cycle exercises.
Fifteen men performed no-countermovement jump (noCMJ) and countermovement jump (CMJ) using only ankle joint with three different loads (0, 30, and 70% of 1 repetition maximum (RM)). Mean torque, angular velocity, power, and fascicle length of the medial gastrocnemius muscle were measured during jumping. In addition, the relative differences in the measured variables of CMJ compared to noCMJ were defined as pre-stretch augmentation.
During concentric phase, the pre-stretch augmentation in angular velocity and power was significantly correlated with that in tendon shortening velocity (except for 70%1RM) but not in fascicle shortening velocity. The increases in tendon length during eccentric phase of CMJ were highly correlated with mean power during concentric phase for all load conditions.
These results suggest that the tendon shortening velocity during concentric phase and the amount of tendon lengthening during eccentric phase (i.e., tendon dynamics) strongly contribute to increased performance in stretch-shortening exercises.
本研究旨在确定外部负荷对拉长-缩短周期运动中离心阶段肌腱延长贡献和向心阶段肌腱缩短速度的影响。
15名男性仅使用踝关节进行无反向运动跳跃（noCMJ）和反向运动跳跃（CMJ），采用三种不同负荷（1次重复最大值（RM）的0%、30%和70%）。在跳跃过程中测量腓肠肌内侧的平均扭矩、角速度、功率和肌束长度。此外，将CMJ与noCMJ测量变量的相对差异定义为预拉伸增强。
在向心阶段，角速度和功率的预拉伸增强与肌腱缩短速度的预拉伸增强显著相关（70%1RM除外），但与肌束缩短速度无关。在所有负荷条件下，CMJ离心阶段肌腱长度的增加与向心阶段的平均功率高度相关。
这些结果表明，向心阶段的肌腱缩短速度和离心阶段的肌腱延长量（即肌腱动力学）对拉长-缩短运动中运动表现的提高有很大贡献。
