Faculty of Sport and Health Science, Ritsumeikan University, 1-1-1 Nojihigashi, Kusatsu, Shiga, 525-8577, Japan.
Institute of Biomechanics and Orthopaedics, German Sport University Cologne, Am Sportpark Müngersdorf 6, 50933, Köln, Germany.
Eur J Appl Physiol. 2018 Feb;118(2):475-481. doi: 10.1007/s00421-017-3791-x. Epub 2017 Dec 20.
Unilateral leg stiffness is a key contributor to sprint running speed, thereby great bilateral deficit (BLD) of leg stiffness would be expected to be observed in sprinters. However, it remains clear only BLD of leg stiffness at the preferred hopping frequency in non-sprinters. The purpose of this study was to clarify the BLD of spring-like behaviour in hopping at various frequencies and the effect of chronic adaptation via sprint running experience on BLD during the hopping.
Fifteen male experienced sprinters and 12 male novices participated in this study. They were instructed to hop in place at three frequencies (2.0, 2.5, and 3.0 Hz), and to perform hopping with maximal effort. Ground reaction forces (GRF) of both legs during the hopping were recorded using two force plates.
At higher hopping frequencies during the unilateral and bilateral hopping, smaller peak value of vertical GRF (F ) and greater leg stiffness (K ) were significantly observed. The BLD index of F and the BLD index of K were significantly smaller at higher hopping frequencies. No significant differences of BLD index of F and BLD index of K were observed between sprinters and novices.
Our results demonstrate that neuromuscular inhibition in the contralateral leg changes during the hopping based on hopping frequency. This suggests that plyometric training in the beginning of rehabilitation should involve bilateral jumping at a high frequency. In experienced sprinters, detailed mechanics of chronic neuromuscular adaptation via unilateral facilitation of spring-like behaviour should be assessed by measuring electromyographic activity.
单侧腿部僵硬是短跑速度的关键贡献因素，因此短跑运动员的腿部僵硬双侧明显不足（BLD）是可以预期的。然而，目前仅在非短跑运动员中观察到了在非偏好跳跃频率下腿部僵硬的 BLD。本研究的目的是阐明在各种频率下跳跃时的弹簧样行为的 BLD 以及通过短跑经验进行慢性适应对跳跃时的 BLD 的影响。
15 名有经验的男性短跑运动员和 12 名男性新手参加了这项研究。他们被要求以三种频率（2.0、2.5 和 3.0 Hz）原地跳跃，并以最大努力进行跳跃。使用两个力板记录双腿在跳跃过程中的地面反作用力（GRF）。
在单侧和双侧跳跃的较高跳跃频率下，垂直 GRF（F）的峰值和腿部刚度（K）明显较小。在较高的跳跃频率下，F 的 BLD 指数和 K 的 BLD 指数均显著较小。短跑运动员和新手之间的 F 的 BLD 指数和 K 的 BLD 指数没有显著差异。
我们的结果表明，基于跳跃频率，对侧腿部的神经肌肉抑制在跳跃过程中发生变化。这表明在康复的早期阶段，增强式训练应包括高频的双侧跳跃。在有经验的短跑运动员中，通过单侧促进弹簧样行为的慢性神经肌肉适应的详细力学特性，应通过测量肌电图活动来评估。
