Department of Physical Education, College of Sciences in Education, Yonsei University, Seoul, Republic of Korea.
Department of Silver Industrial Engineering, College of Future Human Resource Development, Kangnam University, Yongin, Republic of Korea.
J Electromyogr Kinesiol. 2014 Jun;24(3):375-9. doi: 10.1016/j.jelekin.2014.03.004. Epub 2014 Mar 21.
The objectives of this study was to investigate the acute effects of various magnitudes of tendon strain on the mechanical properties of the human medial gastrocnemius (MG) in vivo during controlled heel-drop exercises. Seven male and seven female volunteers performed two different exercises executed one month apart: one was a heel-drop exercise on a block (HDB), and the other was a heel-drop exercise on level floor (HDL). In each regimen, the subjects completed a session of 150 heel-drop exercises (15 repetitions×10 sets; with a 30 s rest following each set). Before and immediately after the heel-drop exercise, the ankle plantar flexor torque and elongation of the MG were measured using a combined measurement system of dynamometry and ultrasonography and then the MG tendon strain and stiffness were evaluated in each subject. The tendon stiffness measured prior to the exercises was not significantly different between the two groups 23.7±10.6N/mm and 24.1±10.0N/mm for the HDB and HDL, respectively (p>.05). During the heel-drop exercise, it was found that the tendon strain during the heel-drop exercise on a block (8.4±3.7%) was significantly higher than the strain measured on the level floor (5.4±3.8%) (p<.05). In addition, the tendon stiffness following the heel-drop exercise on a block (32.3±12.2N/mm) was significantly greater than the tendon stiffness measured following the heel-drop exercise on the level floor (25.4±11.4N/mm) (p<.05). The results of this study suggest that tendon stiffness immediately following a heel-drop exercise depends on the magnitude of tendon strain.
本研究的目的是在受控跟腱下落运动过程中，体内研究不同程度的跟腱应变对人类内侧腓肠肌（MG）机械性能的急性影响。7 名男性和 7 名女性志愿者在相隔一个月的时间内进行了两种不同的运动：一种是在木块上进行跟腱下落运动（HDB），另一种是在水平地板上进行跟腱下落运动（HDL）。在每种方案中，受试者完成 150 次跟腱下落运动（15 次重复×10 组；每组后休息 30 秒）。在跟腱下落运动之前和之后，使用动态测功仪和超声相结合的测量系统测量踝关节跖屈肌扭矩和 MG 的伸长率，然后在每个受试者中评估 MG 肌腱应变和刚度。在练习之前测量的肌腱刚度在两组之间没有显著差异，HDB 和 HDL 分别为 23.7±10.6N/mm 和 24.1±10.0N/mm（p>.05）。在跟腱下落运动过程中，发现木块上的跟腱下落运动期间的肌腱应变（8.4±3.7%）明显高于水平地板上的应变（5.4±3.8%）（p<.05）。此外，在木块上进行跟腱下落运动后，肌腱刚度（32.3±12.2N/mm）明显大于在水平地板上进行跟腱下落运动后测量的肌腱刚度（25.4±11.4N/mm）（p<.05）。本研究结果表明，跟腱下落运动后即刻的肌腱刚度取决于肌腱应变的大小。
