Fujimori Toshihide, Sado Natsuki
Graduate School of Comprehensive Human Sciences, University of Tsukuba, Tsukuba, Japan.
Japan Society for the Promotion of Science, Tokyo, Japan.
Physiol Rep. 2025 May;13(9):e70370. doi: 10.14814/phy2.70370.
Tendon compliance facilitates power exertion during stretch-shortening cycle exercises through muscle-tendon interaction. Tendons stiffen in response to mechanical loadings, and their stiffness sometimes affects motor performance, but no consensus has been reached yet. We investigated the gastrocnemius muscle-tendon properties of 10 male amateur high jumpers and 14 untrained males. Participants performed maximum voluntary contraction (MVC) of ankle plantar flexion. We measured the maximum joint torque and Achilles tendon stiffness using a torque dynamometer for force measurement, an ultrasound apparatus to track tendon elongation, and a motion capture system to correct joint rotation. High jumpers exerted significantly greater MVC torque than untrained individuals (152.8 ± 31.8 vs. 103.6 ± 18.9 Nm). Tendon stiffness did not significantly differ between groups (287.3 ± 90.9 vs. 258.4 ± 85.6 N/mm). This suggests that strengthening muscles and stiffening tendons may independently adapt through high jump training. In high jumpers, high jump personal best record significantly correlated with MVC torque (r = 0.73) but not significantly correlated with tendon stiffness (r = -0.07). Muscle force exertion ability enhanced by training should be important for improving high jump performance, while tendon stiffening is not necessary for performance. We suggest that humans may inherently have adequate tendon properties for jumping, even without specific training.
肌腱顺应性通过肌肉-肌腱相互作用在拉长-缩短周期运动中促进力量发挥。肌腱会因机械负荷而变硬，其硬度有时会影响运动表现，但尚未达成共识。我们研究了10名男性业余跳高运动员和14名未受过训练的男性的腓肠肌-肌腱特性。参与者进行了踝关节跖屈的最大自主收缩（MVC）。我们使用用于力测量的扭矩测力计、用于跟踪肌腱伸长的超声设备和用于校正关节旋转的运动捕捉系统，测量了最大关节扭矩和跟腱硬度。跳高运动员施加的MVC扭矩明显大于未受过训练的个体（152.8±31.8对103.6±18.9 Nm）。两组之间的肌腱硬度没有显著差异（287.3±90.9对258.4±85.6 N/mm）。这表明通过跳高训练，肌肉强化和肌腱变硬可能会独立适应。在跳高运动员中，跳高个人最好成绩与MVC扭矩显著相关（r = 0.73），但与肌腱硬度没有显著相关性（r = -0.07）。训练增强的肌肉力量发挥能力对于提高跳高成绩应该很重要，而肌腱变硬对于成绩并非必要。我们认为，即使没有特定训练，人类可能天生就具有适合跳跃的足够肌腱特性。
