Department of Mechanical Engineering, University of Melbourne, Melbourne, VIC, 3010, Australia,
Eur J Appl Physiol. 2013 Nov;113(11):2813-28. doi: 10.1007/s00421-013-2713-9. Epub 2013 Sep 8.
The human biarticular hamstrings [semimembranosus (SM), semitendinosus (ST) and biceps femoris long head (BF(LH))] have an important role in running. This study determined how hamstrings neuro-mechanical behaviour changed with faster running, and whether differences existed between SM, ST and BF(LH).
Whole-body kinematics and hamstrings electromyographic (EMG) activity were measured from seven participants running at four discrete speeds (range: 3.4 ± 0.1 to 9.0 ± 0.7 m/s). Kinematic data were combined with a three-dimensional musculoskeletal model to calculate muscle-tendon unit (MTU) stretch and velocity. Activation duration and magnitude were determined from EMG data.
With faster running, MTU stretch and velocity patterns remained similar, but maxima and minima significantly increased. The hamstrings were activated from foot-strike until terminal stance or early swing, and then again from mid-swing until foot-strike. Activation duration was similar with faster running, whereas activation magnitude significantly increased. Hamstrings activation almost always ended before minimum MTU stretch, and it always started before maximum MTU stretch. Comparing the hamstrings, maximum MTU stretch was largest for BF(LH) and smallest for ST irrespective of running speed, while the opposite was true for peak-to-peak MTU stretch. Furthermore, peak MTU shortening velocity was largest for ST and smallest for BF(LH) at all running speeds. Finally, for the two fastest running speeds, the amount of MTU stretch that occurred during terminal swing after activation had started was less for BF(LH) compared to SM and ST.
Differences were evident in biarticular hamstrings neuro-mechanical behaviour during running. Such findings have implications for hamstrings function and injury.
人体双关节腘绳肌（半膜肌（SM）、半腱肌（ST）和股二头肌长头（BF（LH）））在跑步中起着重要作用。本研究旨在确定腘绳肌神经力学行为如何随跑步速度的加快而变化，以及 SM、ST 和 BF（LH）之间是否存在差异。
从 7 名参与者在 4 个离散速度（范围：3.4±0.1 至 9.0±0.7 m/s）下跑步时，测量了全身运动学和腘绳肌肌电图（EMG）活动。运动学数据与三维肌肉骨骼模型相结合，计算肌肉肌腱单位（MTU）拉伸和速度。从 EMG 数据中确定激活持续时间和幅度。
随着跑步速度的加快，MTU 拉伸和速度模式保持相似，但最大值和最小值显著增加。腘绳肌从脚着地开始激活，直到终末期或早期摆动，然后从中间摆动再次激活，直到脚着地。随着跑步速度的加快，激活持续时间相似，而激活幅度显著增加。腘绳肌激活几乎总是在 MTU 最小拉伸之前结束，并且总是在 MTU 最大拉伸之前开始。比较腘绳肌，无论跑步速度如何，BF（LH）的最大 MTU 拉伸最大，而 ST 的最小 MTU 拉伸最大，而峰峰值 MTU 拉伸则相反。此外，在所有跑步速度下，ST 的最大 MTU 缩短速度最大，而 BF（LH）的最小 MTU 缩短速度最小。最后，对于两个最快的跑步速度，在激活开始后终端摆动期间发生的 MTU 拉伸量，BF（LH）比 SM 和 ST 少。
在跑步过程中，双关节腘绳肌的神经力学行为存在明显差异。这些发现对腘绳肌功能和损伤有影响。
