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首页> 外文期刊>Journal of Biomechanics >Evidence of residual force enhancement for multi-joint leg extension.
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Evidence of residual force enhancement for multi-joint leg extension.

机译：多关节腿伸展时残余力增强的证据。

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摘要

Force enhancement is a well accepted property of skeletal muscle and has been observed at all structural levels ranging from single myofibrils to voluntarily activated m. quadriceps femoris in vivo. However, force enhancement has not been studied for multi-joint movements like human leg extension; therefore knowledge about its relevance in daily living remains limited. The purpose of this study was to determine whether there is force enhancement during maximal voluntary multi-joint leg extension. Human leg extension was studied (n=22) on a motor driven leg press dynamometer where external reaction forces under the feet as well as activity of 8 lower extremity muscles were measured. In addition, torque in the ankle and knee joints was calculated using inverse dynamics. The steady-state isometric force, joint torques, and muscle activation after active stretch (20 degrees stretch amplitude at 60 degrees/s) were compared with the corresponding values obtained during isometric reference contractions. There was consistent force enhancement during and following stretch for both forces and joint torques. Potentiation during stretch reached values between 26% and 30%, while a significant force enhancement of 10.5-12.3% and 4.3-7.4% remained 0.5-1 and 2.5-3s after stretch, respectively. During stretch, EMG signals of m. gastrocnemius medialis and lateralis were significantly increased, while following stretch all analyzed muscles showed the same activity as during the reference contractions. We conclude from these results that force enhancement exists in everyday movements and should be accounted for when analyzing or modelling human movement.
机译：力量增强是骨骼肌公认的特性，并且在从单个肌原纤维到自愿激活的肌肉的所有结构水平上都可以观察到。股四头肌在体内。但是，尚未针对诸如人的腿伸展的多关节运动研究力量的增强。因此，关于其在日常生活中的意义的知识仍然有限。这项研究的目的是确定最大自愿多关节腿伸展过程中是否存在力量增强。在电机驱动的腿部压力测力计上研究了人类的腿部伸展（n = 22），其中测量了脚下的外部反作用力以及8个下肢肌肉的活动。此外，使用逆动力学计算了踝关节和膝关节的扭矩。将主动拉伸（60度/ s时的20度拉伸幅度）后的稳态等距力，关节扭矩和肌肉激活与等距参考收缩期间获得的相应值进行比较。在拉伸过程中和拉伸之后，力和关节扭矩均得到一致的增强。拉伸过程中的增强值达到26％至30％之间，而拉伸后分别保持0.5-1和2.5-3s的显着力增强分别为10.5-12.3％和4.3-7.4％。在伸展期间，肌电信号为m。腓肠肌内侧和外侧肌明显增加，而拉伸后所有被分析的肌肉均表现出与参考收缩相同的活动。从这些结果可以得出结论，日常运动中存在力量增强，因此在分析或建模人体运动时应予以考虑。

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