We previously reported that active muscle stiffness could be evaluated in vivo. However, we were not able to investigate active muscle stiffness as more than 250 deg·s^-1 due to the limitation of the torque motor of dynamometer. The aim of the present study was to investigate the effect of angular velocities (including higher angular velocities of more than 250 deg·s^-1) on active muscle stiffness. Eighteen males volunteered for this study. Active muscle stiffness of the medial gastrocnemius muscle was calculated according to changes in the estimated muscle force and fascicle length during fast lengthening at five different angular velocities (100, 200, 300, 500, and 600 deg·s^-1). Electromyographic activities of the lateral gastrocnemius muscle (LG) and soleus muscle (SOL) were evaluated over two different phases: before the stretch (mEMGa) and after the stretch (mMEGb). Active muscle stiffness was higher at 300 than at 100 deg·s^-1, but decreased as the angular velocity increased from 300 to 600 deg·s^-1. There were no differences in mEMGa and mEMGb values among the five angular velocities, whereas mEMGb values were higher than mEMGa for all angular velocities. In conclusion, active muscle stiffness was highest at 300 deg·s^-1 and decreased at both slower and faster angular velocities.

我们之前曾报道过，可以在体内评估活跃的肌肉僵硬度。但是，由于测功机转矩马达的限制，我们无法研究超过250度·s ^-1的主动肌肉刚度。本研究的目的是研究角速度（包括大于250度s ^-1的较高角速度）对主动肌肉僵硬的影响。18名男性自愿参加了这项研究。根据在五种不同的角速度（100、200、300、500和600度s ^-1下快速拉长过程中估计的肌肉力量和束长度）的变化，计算腓肠内侧肌的主动肌肉刚度）。在两个不同阶段评估了腓肠肌外侧肌（LG）和比目鱼肌（SOL）的肌电图活动：拉伸前（mEMGa）和拉伸后（mMEGb）。主动肌肉的刚度在300时高于100 degs ^-1，但随着角速度从300 degs s ^-1增加而降低。在五个角速度之间，mEMGa和mEMGb值没有差异，而对于所有角速度，mEMGb值均高于mEMGa。总之，活跃的肌肉僵硬度在300度^-1时最高，而在较慢和较快的角速度下均下降。