Hobara Hiroaki, Kimura Kozo, Omuro Kohei, Gomi Kouki, Muraoka Tetsuro, Iso Shigeo, Kanosue Kazuyuki
Graduate School of Human Sciences, Waseda University, 2-579-15, Mikajima, Tokorozawa, Saitama, Japan.
J Biomech. 2008;41(3):506-14. doi: 10.1016/j.jbiomech.2007.10.014. Epub 2007 Dec 11.
Understanding the leg and joint stiffness during human movement would provide important information that could be utilized for evaluating sports performance and for injury prevention. In the present study, we examined the determinants of the difference in the leg stiffness between the endurance-trained and power-trained athletes. Seven distance runners and seven power-trained athletes performed in-place hopping, matching metronome beats at 3.0 and 1.5Hz. Leg and joint stiffness were calculated from kinetic and kinematics data. Electromyographic activity (EMG) was recorded from six leg muscles. At both hopping frequencies, the power-trained athletes demonstrated significantly higher leg stiffness than the distance runners. Hip, knee, and ankle joints were analyzed for stiffness and touchdown angles. Ankle stiffness was significantly greater in the power-trained athletes than the distance runners at 3.0Hz as was knee stiffness at 1.5Hz. There was no significant difference in touchdown angle between the DR and PT groups at either hopping frequencies. When significant difference in EMG activity existed between two groups, it was always greater in the distance runners than the power-trained athletes. These results suggest that (1) the difference in leg stiffness between endurance-trained and power-trained athletes is best attributed to increased joint stiffness, and (2) the difference in joint stiffness between the two groups may be attributed to a lack of similarity in the intrinsic stiffness of the muscle-tendon complex rather than in altered neural activity.
了解人体运动过程中的腿部和关节僵硬情况，将提供重要信息，可用于评估运动表现和预防损伤。在本研究中，我们研究了耐力训练和力量训练运动员腿部僵硬程度差异的决定因素。七名长跑运动员和七名力量训练运动员进行原地单脚跳，匹配节拍器在3.0和1.5赫兹的节拍。根据动力学和运动学数据计算腿部和关节僵硬程度。记录了六条腿部肌肉的肌电图活动（EMG）。在两个单脚跳频率下，力量训练运动员的腿部僵硬程度均显著高于长跑运动员。对髋、膝和踝关节的僵硬程度和着地角度进行了分析。在3.0赫兹时，力量训练运动员的踝关节僵硬程度显著高于长跑运动员，在1.5赫兹时，膝关节僵硬程度也是如此。在两个单脚跳频率下，长跑运动员和力量训练运动员组之间的着地角度均无显著差异。当两组之间的肌电图活动存在显著差异时，长跑运动员的差异总是大于力量训练运动员。这些结果表明：（1）耐力训练和力量训练运动员之间腿部僵硬程度的差异最好归因于关节僵硬程度的增加；（2）两组之间关节僵硬程度的差异可能归因于肌腱复合体固有僵硬程度缺乏相似性，而非神经活动的改变。
