Centre for Exercise and Sports Science Research (CESSR), School of Medical and Health Sciences, Edith Cowan University, Joondalup, WA, Australia.
Department of Physical Therapy, College of Staten Island, The City University of New York, Staten Island, NY, USA.
Eur J Neurosci. 2021 May;53(9):3185-3198. doi: 10.1111/ejn.15178. Epub 2021 Mar 18.
The purpose of this study was to investigate changes in muscle spindle sensitivity with early and late soleus reflex responses via tendon taps and transcranial magnetic stimulation, respectively, after an acute bout of prolonged static plantar flexor muscle stretching. Seventeen healthy males were tested before and after 5 min (5 × 60-s stretches) of passive static stretching of the plantar flexor muscles. Maximal voluntary isometric torque and M wave-normalized triceps surae muscle surface electromyographic activity were recorded. Both soleus tendon reflexes, evoked by percussion of the Achilles tendon during rest and transcranial magnetic stimulation-evoked soleus late responses during submaximal isometric dorsiflexion were also quantified. Significant decreases in maximal voluntary isometric plantar flexion torque (-19.2 ± 13.6%, p = .002) and soleus electromyographic activity (-20.1 ± 11.4%, p < .001) were observed immediately after stretching, and these changes were highly correlated (r = 0.76, p < .001). No changes were observed in tendon reflex amplitude or latency or peak muscle twitch torque (p > .05). Significant reductions in soleus late response amplitudes (-46.9 ± 36.0%, p = .002) were detected, although these changes were not correlated with changes in maximal electromyographic activity, torque or tendon reflex amplitudes. No changes in soleus late response latency were detected. In conclusion, impaired neural drive was implicated in the stretch-induced force loss; however, no evidence was found that this loss was related to changes in muscle spindle sensitivity. We hypothesize that the decrease in soleus late response indicates a stretch-induced reduction in a polysynaptic postural reflex rather than spindle reflex sensitivity.
这项研究的目的是通过肌腱敲击和经颅磁刺激分别检测早期和晚期比目鱼肌反射反应，来研究急性长时间静态跖屈肌伸展后肌梭敏感性的变化。17 名健康男性在被动静态伸展跖屈肌 5 分钟（5×60 秒伸展）前后接受测试。记录最大自主等长扭矩和三腿头肌表面肌电图活动的 M 波归一化。还定量评估了在休息时通过跟腱叩击诱发的比目鱼肌肌腱反射和在亚最大等距背屈时经颅磁刺激诱发的比目鱼肌晚期反应。伸展后即刻观察到最大自主等距跖屈扭矩（-19.2±13.6%，p=0.002）和比目鱼肌肌电图活动（-20.1±11.4%，p<0.001）显著降低，这些变化高度相关（r=0.76，p<0.001）。肌腱反射幅度或潜伏期或峰值肌肉抽搐扭矩无变化（p>0.05）。虽然这些变化与最大肌电图活动、扭矩或肌腱反射幅度的变化无关，但仍检测到比目鱼肌晚期反应幅度显著降低（-46.9±36.0%，p=0.002）。比目鱼肌晚期反应潜伏期无变化。总之，神经驱动受损可能与拉伸引起的力丧失有关；然而，没有证据表明这种丧失与肌梭敏感性的变化有关。我们假设比目鱼肌晚期反应的减少表明拉伸诱导的多突触姿势反射减少，而不是肌梭反射敏感性降低。
