長(zhǎng)期以來(lái)，有關(guān)肌肉疲勞的研究多數(shù)局限于肌肉本身的變化?，F(xiàn)在,，蘇黎世大學(xué)和蘇黎世理工學(xué)院的最新論文"Fatigue-induced increase in intracortical communication between mid/anterior insular and motor cortex during cycling exercise"將研究重點(diǎn)轉(zhuǎn)向了大腦研究,，相關(guān)論文發(fā)表在最新一期的European Journal of Neuroscience雜志上,。
我們自主調(diào)動(dòng)肌肉的程度取決于動(dòng)機(jī),、意志力或身體條件以及肌肉的疲勞水平,。而后者會(huì)導(dǎo)致明顯可測(cè)的肌肉性能損傷。由蘇黎世大學(xué)的神經(jīng)心理學(xué)家Kai Lutz和蘇黎世理工學(xué)院運(yùn)動(dòng)科學(xué)與體育研究中心的Urs Boutellier共同主導(dǎo)該項(xiàng)研究,。研究者們首次發(fā)現(xiàn),，在導(dǎo)致肌肉疲勞的運(yùn)動(dòng)過(guò)程中，神經(jīng)元活動(dòng)導(dǎo)致降低肌肉的活力,。
肌肉的神經(jīng)脈沖抑制大腦的有關(guān)肌肉運(yùn)動(dòng)區(qū)域
在最初的研究中,，研究者們揭示來(lái)自肌肉的神經(jīng)脈沖在令人疲倦的耗能運(yùn)動(dòng)過(guò)程中抑制了大腦中有關(guān)肌肉運(yùn)動(dòng)的主區(qū)域。
他們通過(guò)測(cè)試證實(shí)了這一發(fā)現(xiàn),，在測(cè)試中,，參與研究的受試者重復(fù)進(jìn)行大腿收縮運(yùn)動(dòng)直到他們無(wú)法達(dá)到所要求的力度,。
若在脊髓麻醉狀態(tài)下進(jìn)行相同的運(yùn)動(dòng),，則從肌肉到大腦肌肉運(yùn)動(dòng)相關(guān)主要區(qū)域的反應(yīng)中斷,，相應(yīng)的疲勞相關(guān)抑制過(guò)程與肌肉信息正常時(shí)相比要弱得多,。
在第二步中,，通過(guò)使用功能磁共振成像技術(shù),，研究者們對(duì)中斷令人疲倦的耗能活動(dòng)前呈現(xiàn)短暫活力增加并因此釋放有關(guān)該中斷行為信號(hào)的大腦區(qū)域進(jìn)行了定位：丘腦及島皮質(zhì)——兩個(gè)用于分析指示威脅機(jī)體信號(hào)如疼痛和饑餓的區(qū)域,。
神經(jīng)系統(tǒng)對(duì)肌肉性能的調(diào)節(jié)效果
現(xiàn)在，第三項(xiàng)研究顯示,，對(duì)肌肉運(yùn)動(dòng)相關(guān)活力的抑制影響實(shí)際上是通過(guò)島皮質(zhì)介導(dǎo)的：在測(cè)試中,，研究者們使用自行車測(cè)力器測(cè)得島皮質(zhì)與大腦肌肉運(yùn)動(dòng)相關(guān)主區(qū)域之間的通訊在疲勞加重時(shí)變得更為密集,。
“這可以認(rèn)為是證實(shí)了神經(jīng)系統(tǒng)不僅是向大腦傳遞信息,，并且實(shí)際上對(duì)有關(guān)肌肉運(yùn)動(dòng)的活性具有調(diào)節(jié)作用，”Lea Hilty總結(jié)目前的研究成果說(shuō)道,。
Kai Lutz指出,，這些研究成果打開了一些新的研究領(lǐng)域：“這些發(fā)現(xiàn)是探索肌肉疲勞中大腦所起作用中重要的 一步,。基于這些研究,，將不僅僅有可能發(fā)展出優(yōu)化肌肉性能的策略，還可以對(duì)各種疾病中退化的肌肉性能進(jìn)行特定研究,。”
在日常臨床實(shí)踐中,，持續(xù)的受抑機(jī)體性能是一種頻繁觀察到的癥狀，其也可能作為某些藥物的副作用而出現(xiàn),。不過(guò),，慢性疲勞綜合癥通常可在無(wú)任何明顯病因下診斷,。（生物谷Bioon.com）
doi:10.1111/j.1460-9568.2011.07909.x
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Fatigue-induced increase in intracortical communication between mid/anterior insular and motor cortex during cycling exercise
Lea Hilty, Nicolas Langer, Roberto Pascual-Marqui, Urs Boutellier, Kai Lutz
In the present study, intracortical communication between mid/anterior insular and motor cortex was investigated during a fatiguing cycling exercise. From 16 healthy male subjects performing a constant-load test at 60% peak oxygen consumption (VO2peak) until volitional exhaustion, electroencephalography data were analysed during repetitive, artefact-free periods of 1-min duration. To quantify fatigue-induced intracortical communication, mean intra-hemispheric lagged phase synchronization between mid/anterior insular and motor cortex was calculated: (i) at the beginning of cycling; (ii) at the end of cycling; and (iii) during recovery cycling. Results revealed significantly increased lagged phase synchronization at the end of cycling, which returned to baseline during recovery cycling after subjects’ cessation of exercise. Following previous imaging studies reporting the mid/anterior insular cortex as an essential instance processing a variety of sensory stimuli and signalling forthcoming physiological threat, our results provide further evidence that during a fatiguing exercise this structure might not only integrate and evaluate sensory information from the periphery, but also act in communication with the motor cortex. To the best of our knowledge, this is the first study to empirically demonstrate that muscle fatigue leads to changes in interaction between structures of a brain’s neural network.
