Abellaneda Séverine, Guissard Nathalie, Duchateau Jacques
Laboratory of Applied Biology, Institute for Motor Sciences, Université Libre de Bruxelles, Route de Lennik, Brussels, Belgium.
J Appl Physiol (1985). 2009 Jan;106(1):169-77. doi: 10.1152/japplphysiol.90577.2008. Epub 2008 Nov 6.
The increase in passive torque during muscle stretching may constrain the range of motion of a joint. As passive torque can vary substantially among individuals, the present study examined whether the relative lengthening of the myotendinous structures of the medial gastrocnemius (MG) during passive stretching differs among individuals. Sixteen subjects performed passive stretching of the plantar flexor muscles from ankle angles ranging from 10 degrees plantar flexion (-10 degrees ) to 30 degrees dorsiflexion (+30 degrees ). Changes in passive torque, muscle architecture (fascicle length and pennation angle) of the MG and electromyographic activity of MG and soleus were recorded. The results showed that passive torque produced by the plantar flexors increased exponentially (r(2) = 0.99; P < 0.001) with ankle dorsiflexion, whereas MG fascicle length increased linearly from 57.6 +/- 9.1 to 80.5 +/- 10.3 mm (P < 0.001), and pennation angle decreased linearly from 21.2 +/- 4.2 to 14.4 +/- 3.1 degrees (P < 0.001) when the ankle joint angle was moved from -10 degrees to +30 degrees . The relative contribution of muscle (fascicles and aponeuroses) and tendon elongation to the change in length of the muscle-tendon unit (MTU) at 30 degrees dorsiflexion was 71.8 and 28.2%, respectively. However, the adjustment differed across individuals during MTU lengthening; in subjects (62.5%) with small, passive stiffness, the elongation of the free tendon was less and that of the fascicles larger than for subjects (37.5%) with greater stiffness. In conclusion, the results indicate that the strain of muscle and tendon varies among individuals, and difference in the relative compliance of these structures influences MTU lengthening differently during passive stretching.
肌肉拉伸过程中被动扭矩的增加可能会限制关节的活动范围。由于被动扭矩在个体之间可能存在很大差异，本研究探讨了在被动拉伸过程中，腓肠肌内侧头（MG）肌腱结构的相对延长在个体之间是否存在差异。16名受试者进行了跖屈肌的被动拉伸，踝关节角度范围从跖屈10度（-10度）到背屈30度（+30度）。记录了被动扭矩、MG的肌肉结构（肌束长度和羽状角）以及MG和比目鱼肌的肌电图活动的变化。结果表明，随着踝关节背屈，跖屈肌产生的被动扭矩呈指数增加（r² = 0.99；P < 0.001），而当踝关节角度从-10度移动到+30度时，MG肌束长度从57.6±9.1毫米线性增加到80.5±10.3毫米（P < 0.001），羽状角从21.2±4.2度线性减小到14.4±3.1度（P < 0.001）。在背屈30度时，肌肉（肌束和腱膜）和肌腱伸长对肌腱单位（MTU）长度变化的相对贡献分别为71.8%和28.2%。然而，在MTU延长过程中，个体之间的调整存在差异；在被动刚度较小的受试者（62.5%）中，游离肌腱的伸长较少，肌束的伸长大于刚度较大的受试者（占37%）。总之，结果表明肌肉和肌腱的应变在个体之间存在差异，并且这些结构相对顺应性的差异在被动拉伸过程中对MTU延长的影响不同。
