Xu Jingfei, Hug François, Fu Siu Ngor
Department of Rehabilitation Medicine, West China Hospital, Sichuan University, Chengdu 610041, China.
Department of Rehabilitation Sciences, The Hong Kong Polytechnic University, Hong Kong, China.
J Sport Health Sci. 2018 Apr;7(2):245-249. doi: 10.1016/j.jshs.2016.07.001. Epub 2016 Jul 4.
Until recently it has not been possible to isolate the mechanical behavior of individual muscles during passive stretching. Muscle shear modulus (an index of muscle stiffness) measured using ultrasound shear wave elastography can be used to estimate changes in stiffness of an individual muscle. The aims of the present study were (1) to determine the shear modulus-knee angle relationship and the slack angle of the vastus medialis oblique (VMO), rectus femoris (RF), and vastus lateralis (VL) muscles; (2) to determine whether this differs between the muscles.
Nine male rowers took part in the study. The shear modulus of VMO, RF, and VL muscles was measured while the quadriceps was passively stretched at 3°/s. The relationship between the muscle shear modulus and knee angle was plotted as shear modulus-knee angle curve through which the slack angle of each muscle was determined.
The shear modulus of RF was higher than that of VMO and VL when the muscles were stretched over 54° (all <0.01). No significant difference was found between the VMO and VL (all > 0.05). The slack angle was similar among the muscles: 41.3° ± 10.6°, 44.3° ± 9.1°, and 44.3° ± 5.6° of knee flexion for VMO, RF, and VL, respectively ( = 0.626).
This is the first study to experimentally determine the muscle mechanical behavior of individual heads of the quadriceps during passive stretching. Different pattern of passive tension was observed between mono- and bi-articular muscles. Further research is needed to determine whether changes in muscle stiffness are muscle-specific in pathological conditions or after interventions such as stretching protocols.
直到最近，在被动拉伸过程中分离单个肌肉的力学行为仍是不可能的。使用超声剪切波弹性成像测量的肌肉剪切模量（肌肉僵硬度指标）可用于估计单个肌肉僵硬度的变化。本研究的目的是：（1）确定股内侧斜肌（VMO）、股直肌（RF）和股外侧肌（VL）的剪切模量与膝关节角度的关系以及松弛角；（2）确定这些肌肉之间是否存在差异。
九名男性赛艇运动员参与了本研究。在以3°/秒的速度被动拉伸股四头肌时，测量VMO、RF和VL肌肉的剪切模量。绘制肌肉剪切模量与膝关节角度的关系曲线，即剪切模量 - 膝关节角度曲线，通过该曲线确定每块肌肉的松弛角。
当肌肉拉伸超过54°时，RF的剪切模量高于VMO和VL（均P<0.01）。VMO和VL之间未发现显著差异（均P>0.05）。各肌肉的松弛角相似：VMO、RF和VL的膝关节屈曲松弛角分别为41.3°±10.6°、44.3°±9.1°和44.3°±5.6°（P = 0.626）。
这是第一项通过实验确定股四头肌各单头肌在被动拉伸过程中肌肉力学行为的研究。单关节和双关节肌肉之间观察到不同的被动张力模式。需要进一步研究以确定在病理状况下或在诸如拉伸方案等干预后，肌肉僵硬度的变化是否具有肌肉特异性。
