肌疲劳对主动肌及其拮抗肌脊髓运动神经元兴奋性的影响

目的:探讨肌疲劳发生过程中主动肌及其拮抗肌脊髓运动神经元兴奋性的变化规律。方法:以10名健康男子为研究对象,采用50%随意性最大肌肉收缩的踝关节等长收缩形式,观察踝关节跖屈和背屈运动前后比目鱼肌诱发肌电图H波和M波的变化。结果:(1)跖屈运动引起比目鱼肌疲劳后,H/Mmax(最大H波与最大M波振幅比值)下降至运动前的63.07±16.57%(P<0.01),且运动终止后较长时间仍未恢复到运动前水平。(2)背屈运动引起胫骨前肌疲劳后,其拮抗肌比目鱼肌H/Mmax下降至运动前的85.33±10.25%(P<0.01),而后逐渐恢复至运动前水平。(3)背屈运动引起胫骨前肌疲劳后,其拮抗肌比目鱼肌H波阈值与安静时比较明显升高。结论:肌疲劳时,不但主动肌脊髓运动神经元兴奋性受到抑制,拮抗肌脊髓运动神经元兴奋性也受到类似影响。     

高频正弦波振动对尾吊大鼠比目鱼肌H反射变化的改善作用

目的 本研究旨在进一步观察尾吊大鼠与肌梭兴奋性传入有关的α运动神经元的兴奋性的变化,并探讨高频正弦波振动比目鱼肌能否对这种兴奋性的变化产生影响.方法 用大鼠尾部悬吊法建立模拟失重模型.对比目鱼肌施加机械正弦波振动(100 Hz,0.3 mm).电刺激坐骨神经,同时记录比目鱼肌肌电图.结果 尾吊和高频正弦波振动均不影响H反射幅值在刺激强度增加时的变化趋势.尾吊14d后,大鼠最大运动反应(Mmax)和Hmax与Mmax之比(Hmax/Mmax)明显减小,而在尾吊期间给予高频振动后二者没有显著性差异.结论 模拟失重状态下肌梭的传入冲动减少可引起大鼠脊髓运动神经元兴奋性降低.高频正弦波振动比目鱼肌可以提高模拟失重条件下脊髓仅运动神经元的兴奋性.     

双侧屈伸肘运动中主动肌与拮抗肌的表面肌电图变化

目的:通过观察肘关节屈伸运动过程中主动肌和拮抗肌表面肌电图(sEMG)信号活动,探讨不同强度运动诱发肌肉疲劳的中枢运动控制规律。方法:11名男性受试者完成3组不同负荷的肘关节屈伸运动实验,采用线性(AEMG、MPF)和非线性(C(n)、%DET)分析方法,对不同强度下屈伸肘运动中主动肌(肱二头肌,BB)和拮抗肌(肱三头肌,TB)的sEMG信号及共激活比值(CR)进行研究。结果:向心屈肘关节运动条件下,主动肌BB的AEMG呈现5kg和15kg不变而10kg负荷随收缩次数的递增逐渐增加的现象,拮抗肌TB的AEMG在所有运动强度条件下均未表现出明显增加的现象;向心屈肘关节运动过程中,AEMG和MPF斜率受运动负荷强度和主动肌/拮抗肌因素双重影响,C(n)和%DET斜率仅存在运动强度效应,不存在主动肌/拮抗肌效应;向心屈肘关节运动过程中主动肌和拮抗肌的CRAEMG、CRMPF、CRC(n)和CR%DET均具有明显的运动强度效应而无收缩次数效应,且向心屈肘和离心伸肘运动有相似的变化规律。结论:共激活现象在线性指标和非线性指标上呈现不同变化;共激活作用的变化受运动强度的影响,不受肌肉疲劳因素的影响;不同强度肘关节屈伸运动过程中,中枢神经系统对主动肌和拮抗肌运动单位的募集可能采取了不同的控制策略。     

蟾蜍脊髓运动神经元背侧树突突触的定位及分布

在蟾蜍脊髓诱发电位的研究中,刺激腓肠肌与胫前肌向心神经在腰膨大部位出现恒定的电反应,即兴奋性突触电位。该突触的突触前成分是肌向心神经纤维;突触后成分是运动神经元向背侧延伸的树突。两者可能在背柱形成突触,为运动神经元的背侧树突突触(Dorsal dendritic synapse)。这一判断支持和补充了Brookhart及Szekely的     

氯化琥珀胆碱对大鼠比目鱼肌离体单一肌梭传入放电的影响

目的 探讨不同浓度氯化琥珀胆碱(suxamethonium chloride,Sch)对大鼠比目鱼肌离体单一肌梭传入放电的影响。方法 采用空气隔绝法记录大鼠比目鱼肌离体单一肌梭传入放电,分别给予25 mg/L、50mg/L、75 mg/L、100 mg/L、125 mg/L Sch灌流后,观察大鼠比目鱼肌离体单一肌梭传入放电的变化。结果1)给予25 mg/L Sch灌流后,大鼠比目鱼肌离体单一肌梭传入放电较灌流前无明显变化;2)分别给予50 mg/L、75 mg/L Sch灌流后,肌梭传入放电较灌流前明显增多(P0.01);3)给予100 mg/L Sch灌流后,肌梭传入放电较灌流前无明显变化;4)给予125 mg/L Sch灌流后,肌梭传入放电较灌流前明显减少(P0.05)。结论 一定浓度的氯化琥珀胆碱(50~75 mg/L)可特异性地兴奋肌梭,使大鼠比目鱼肌离体单一肌梭传入放电明显增多;氯化琥珀胆碱浓度过高(≥125mg/L)反而会抑制大鼠比目鱼肌离体单一肌梭的传入放电。     

30秒全力蹬踏自行车运动中下肢肌肉协同活动特征研究

目的:观察30秒全力蹬踏自行车运动中下肢肌肉表面肌电信号随运动时间变化的特征,揭示该运动过程中下肢主要用力肌肉的协同活动规律。方法:10名场地自行车运动员(男7名,女3名,年龄21.5±4.7岁)在Wattbike功率自行车上进行30秒全力蹬踏自行车运动,记录输出功率、蹬踏频率和下肢股直肌、股肌(股内侧肌、股外侧肌)、腘绳肌(股二头肌、半腱肌)、胫骨前肌、腓肠肌外侧头、比目鱼肌的表面肌电信号,并采用高速摄像机记录运动影像。基于运动影像确定蹬踏周期起止点。基于表面肌电信号获取各测试肌肉的肌电中值频率、活动水平、激活时间和三组肌肉的协同收缩比率(CAI胫骨前肌/比目鱼肌、CAI股肌/腓肠肌、CAI股肌/腘绳肌)。结果:在运动结束即刻,蹬踏频率和输出功率分别相对于最大值下降了21.51%±5.40%和56.17%±9.91%。股直肌、股肌、腓肠肌肌电幅值、激活时间和肌电中值频率随运动持续时间的增加表现出单调递减(P<0.05)。肌肉协同收缩比率CAI胫骨前肌/比目鱼肌随运动持续时间的增加单调递增,而协同收缩比率CAI股肌/腓肠肌表现出单调递减趋势(P<0.05)。结论:在30秒全力蹬踏自行车运动中,股直肌、股肌、胫骨前肌、腓肠肌都出现较深的肌肉疲劳。在此过程中,下肢肌肉的协同活动呈现非同步性的变化,引起股肌-腓肠肌动力传递效率下降和踝关节拮抗肌共收缩比率增加。     

MRI对Duchenne肌营养不良的诊断价值

目的 探讨MRI对Duchenne肌营养不良的诊断价值.方法 收集确诊为Duchenne肌营养不良的男性患儿64例,行盆底(62例)、大腿(62例)、小腿(59例)(共692组肌群)MRI检查,轴位T1WI、T2 WI、SPIR及冠位T2 WI扫描.由2名高年资医生独立重点观察:(1)肢体肥大或萎缩;(2)病变肌肉对称性;(3)病变肌肉累及分布;(4)MRI信号特点(脂肪浸润或炎性水肿);(5)9例治疗后复查改变.结果 (1)肢体肥大者17例(26.56％),萎缩者12例(18.75％).(2)4例(6.25％)两侧肌群累及不对称,余肌群受累基本对称.(3)①盆肌:臀大肌受累87.10％,盆底收肌67.74％(x2=6.643,P=0.010).②大腿:股四头肌82.26％,股二头肌75.81％,半腱肌62.90％,半膜肌80.65％,缝匠肌69.23％,股薄肌22.58％(x2=67.075,P=0.000).③小腿:胫骨前肌23.73％,胫骨后肌32.20％,腓肠肌81.36％,比目鱼肌57.63％(x2=48.218,P=0.000).上述肌群均表现有脂肪浸润共352组(352/692,50.87％).其中,发现炎性水肿者203组(203/352,57.67％).≥50％伴有炎性水肿肌群见于臀大肌、股四头肌、胫骨前肌、胫骨后肌和比目鱼肌.(4)9例患者经2～5年治疗复查,MRI变化不一致.结论 MRI对Duchenne肌营养不良的检查诊断有重要作用.下肢肌肉改变应重点观察大肌群如臀大肌、股四头肌、半膜肌及腓肠肌等.     

依托咪酯在全麻诱导时引发肌颤的研究

目的　探讨应用依托咪酯行全麻诱导时肌颤的发生与脑电的关系 ,并观察预先小剂量注射依托咪酯对诱导剂量的依托咪酯诱发肌颤的影响。方法　 6 0例上腹部手术病人ASAⅠ～Ⅱ级 ,随机分为 4组 :Ⅰ组 (依托咪酯 0 .3mg/kg ,n =15 ) ;Ⅱ组 (依托咪酯 0 .0 75mg/kg ,n =15 ) ;Ⅲ组 (依托咪酯 0 .1mg/kg ,n =15 ) ;Ⅳ组 (生理盐水预处理组 ,n =15 )。 结果　Ⅳ组中肌颤的潜伏期最短并持续时间最长。与Ⅳ组比较 :Ⅰ组和Ⅲ组肌颤的潜伏期延长且持续时间缩短 ,但无显著性差异 (P >0 .0 5 )。Ⅱ组中肌颤的潜伏期与持续时间与Ⅳ组比较有显著性差异 (P <0 .0 5 )。脑电图显示肌颤发生时 ,无惊厥波出现。结论　诱导剂量的依托咪酯所引发的肌颤与惊厥无关。应用 0 .0 75mg/kg依托咪酯进行预处理可明显减轻肌颤的发生     

逆行比目鱼肌骨膜附皮质骨瓣治疗Gustilo Ⅲ型胫骨远端骨折

目的 设计一种新的治疗Gustilo Ⅲ型胫骨远端骨折的组合移植方法.方法 1998年10月-2008年11月对46例Gustilo Ⅲ型胫骨远端骨折患者者进行逆行比目鱼肌+骨膜附皮质骨瓣组合移植.Gustilo Ⅲa型16例,Ⅲb型30例.其中男29例,女17例;年龄23-77岁,平均36岁.手术方法:骨折固定完成后,显露比目鱼肌内侧半在胫骨上端附着点,骨膜连同胫骨表面薄层皮质骨片一并切取,比目鱼肌连同骨膜薄层皮质骨片向下翻转覆盖骨与软组织缺损处固定.结果 随访时间30～46个月,平均26个月.46例中9例采用髂骨植骨,37例采用骨膜附皮质骨瓣移植.骨愈合时间18～37周,平均22周.外固定钉道感染1例.患肢踝关节活动正常及接近正常38例,关节受限8例.全部患者行走正常,5例感觉跑步时后蹬力不足.结论 逆行比目鱼肌+骨膜附皮质骨瓣移植方法简单,可同时重建骨与软组织缺损,促进骨折愈合,是治疗Gustilo Ⅲ型胫骨远端骨与软组织缺损的有效方法.     

大鼠坐骨神经损伤急性期缓激肽在相应脊髓前角的变化规律

应用免疫细胞化学方法,结合图像分析仪,研究了缓激肽在脊髓腰骶段及L_(4～6)背根节的分布,以及坐骨神经切断后,它在相应前角运动神经元的相对含量的变化规律。结果:缓激肽分布于L_(4～6)背根节及腰骶髓灰质的第Ⅱ、Ⅲ、Ⅳ、Ⅸ层神经元及脊髓白质的神经胶质细胞和神经纤维。在神经损伤的研究中,相应脊髓前角运动神经元的缓激肽含量,损伤后第15h是减少的,以后逐渐增多,至第72h仍维持在高位水平。     

Electromyographic changes of agonist and antagonist calf muscles during maximum isometric induced fatigue

The purpose of this study was to examine electromyographic changes of the agonist and antagonist muscles during fatigue. Nine healthy, untrained subjects exerted a maximum voluntary heel lifting contraction with their dominant limb. The EMG activity over the soleus and the tibialis anterior muscles was recorded during the contraction. The results showed that the torque output during heel lifting and the soleus EMG activity decreased, whereas the tibialis anterior EMG revealed a small but non-significant decrease. However, the ratio of the tibialis anterior to the soleus EMG increased significantly at the end of the fatigue protocol, a fact that reveals that the decrease rate of the antagonist's activity was significantly lower than the decrease rate of the agonist activity. It is concluded that during a maximal fatigue protocol, both the agonist and antagonist muscle activity may decline, however, the slower rate of antagonist's activity decrease relative to the agonist's activity is a finding that requires further investigation. This finding may reflect a higher level of agonist and antagonist muscle co-activation and probably a relatively higher opposing torque from the antagonist muscles at the end of the fatigue session.     

Inhibitory effects of combined agonist and antagonist muscle vibration on H-reflex in man

Vibration alters human sensory motor performance. Changes in the excitability of spinal reflex mechanisms may be responsible for the majority of the observed alterations. We studied the differential effects of vibration locally applied to gastrocnemius soleus and tibialis anterior muscles separately and to both muscles simultaneously. From the results, it is deduced that combined agonist and antagonist muscle vibration may lead to summative interaction between pre- and postsynaptic inhibition at motoneuronal level. Whole-body vibration is taken to mean a combination of synchronous vibrations applied locally and simultaneously to several muscles. The results also demonstrate that the level of inhibition of the H-reflex resulting from the vibration is directly related to the displacement amplitude of the vibration, regardless of the frequency.     

Magnetic stimulation of the motor cortex in healthy persons]

In 49 healthy volunteers the motor cortex was stimulated transcranially by the intensive short magnetic field and the responses of the m. abductor digiti minimi (m. ADM) in 20 volunteers were recorded and of the m. tibialis anterior (m. TA) in 29 volunteers in relaxation and in mild contraction. In all volunteers by the electric stimulation of the ulnar nerve in the region of the wrist and the peroneal nerve in the region of the fibular capitulum there have been measured the F wave latency, distal latency of M responses and the conduction time of the peripheral motor neuron has been calculated. The difference between the latency of m. ADM and n. TA responses and the conduction time of the peripheral motor nerve represented the central motor conduction time from the motor cortex to the motor neurons of the anterior horns of the spinal cord (C8 and L4 segments). The normative values of the absolute latencies of the muscle responses and the central motor conduction time in the relaxed and contracted muscle are calculated as well as the normatives of the normal differences in latencies and the central motor conduction time between the left and right side of the same subject.     

冬虫夏草提取液增强大鼠肌梭传入放电频率

目的:探讨冬虫夏草(CS)提取液对大鼠比目鱼肌肌梭传入放电的影响。方法:雌性SD大鼠20只,麻醉后行气管插管术和颈外静脉插管术,在比目鱼肌神经上分离神经细束,记录肌梭的传入放电,观察CS对放电的影响。结果:分别注射50 mg.kg-1、100 mg.kg-1、150 mg.kg-1CS提取液后,肌梭传入放电峰值频率均明显增加,且随着药物浓度升高,放电频率明显增加,放电持续时间明显延长。结论:CS提取液明显增加大鼠肌梭的传入放电频率,且与剂量呈依赖关系。     

大鼠坐骨神经损伤急性期激肽原在脊髓前角的变化规律

应用免疫细胞化学方法，结合图像分析仪，研究了激肽原在腰骶髓及Ｌ４～Ｌ６脊神经节的分布，以及坐骨神经切断后，其在相应的前角运动神经元的相对含量的变化规律。研究发现：激肽原分布于Ｌ４～Ｌ６脊神经节及腰骶髓灰质的第Ⅱ，Ⅲ，Ⅳ，Ⅸ层神经元及脊髓白质的神经胶质细胞和神经纤维。在神经损伤后，相应脊髓前角运动神经元的激肽原相对含量，在损伤后第１５ｈ是减少的。以后逐渐增多，到损伤后２４ｈ基本恢复到对照组水平，在第４８ｈ，７２ｈ，其含量明显超过对照组。     

Muscle degeneration after exercise in rats

To search for morphological changes in muscle, related to overuse syndromes of muscle due to exercise, groups of untrained rats ran on a treadmill for 1 h at submaximal intensity. Each group was sacrificed at a different interval after the end of the exercise. To evaluate the physiologic load, the colonic temperature and blood lactate level were determined. The right hindlimb was fixated with buffered glutaraldehyde, injected into the femoral artery, and different muscles were dissected and prepared for electron and light microscopy. The muscles of the left limb were frozen in liquid Freon and used for histochemistry. Signs of degeneration were noted in the soleus, rectus femoris, and vastus lateralis muscles, but were absent in the gastrocnemius, tibialis anterior, extensor digitorum, and biceps femoris muscles. Immediately after exercise, only minor signs of degeneration were observed at the ultrastructural level, while after 2-3 h degeneration became clearly visible at the light microscopic level. The most pronounced changes were observed 24-48 h after exercise, whereafter regeneration occurred. Only 2%-5% of all fibers in the soleus muscle showed signs of degeneration, while in the vastus lateralis and rectus femoralis muscle less than 0.5% of the fibers were affected. The affected fibers showed degeneration only in segments with a length between 150-1250 micrometers. The affected fibers in the soleus and vastus lateralis muscles belong to the type I population, while in the rectus femoris type I as well as type II fibers were affected.     

Plantar flexion torque as a function of time of day

The possible peripheral and/or central origin in the mechanisms responsible for day-time fluctuation in maximal torque of the triceps surae muscle were investigated with a special emphasis on antagonist muscle coactivation. Eleven healthy male subjects (physical education students) took part in this investigation. The electromechanical properties of the plantar flexor muscles were recorded at two different times of day: between 06:00 h and 08:00 h in the morning and between 17:00 h and 19:00 h in the evening. To investigate peripheral mechanisms, the posterior tibial nerve was stimulated at rest, using percutaneous electrical stimuli, to evoke single twitch, double twitch, and maximal tetanic contraction (100 Hz). Maximal voluntary contraction of the plantar flexors was also assessed by means of the relative electromyographic activity of respective agonist and antagonist muscles (soleus, gastrocnemius medialis, gastrocnemius lateralis, and tibialis anterior). A double twitch was delivered during maximal voluntary plantar flexion to record muscle activation (i.e., interpolated twitch technique). The coactivation level of the tibialis anterior muscle during plantar flexion was calculated. The results indicated a significant decrease in maximal voluntary muscle torque of triceps surae in the evening as compared with the morning (-7.0 %; p < 0.05). Concerning the central command, when extrapolated by the twitch interpolation technique, the decrease in mean activation level of -6.8 % was consistent with the fluctuation in torque (-7.0 %). Soleus muscle electromyographic activity (normalized to the M-wave) showed a significant decline (21.6 %; p < 0.001). Moreover, individual changes in MVC percentage were significantly related to those of normalized electromyographic activity of the soleus muscle (r = 0.688; p < 0.01). Thus, it indicated that the subject's capacity to activate the soleus muscle was affected by the time of day. The coactivation level in the tibialis anterior muscle during plantar flexion did not change significantly in the evening. Concerning peripheral mechanisms, we observed a decrease in maximal M-wave amplitude for soleus and gastrocnemii, associated with unchanged single twitch and tetanus torque. To conclude, impairment in soleus muscle central command seemed to be the mechanism in the origin of torque failure. Such information would be of importance in the investigation of day-time fluctuations in complex motor task performances implicating the triceps surae muscle.     

100 Hz正弦波振动对悬吊大鼠比目鱼肌肌梭传入放电的影响

目的探讨100 Hz正弦波振动对尾部悬吊大鼠比目鱼肌肌梭传入放电的影响.方法采用尾部悬吊大鼠模型模拟失重,用振动仪实施100 Hz正弦波刺激,利用从背根分离神经细束并记录比目鱼肌肌梭传入放电的方法,7 d后观察大鼠比目鱼肌肌梭传入放电的变化.结果 1)吊尾7 d后,大鼠比目鱼肌肌梭的传入放电与对照组相比明显减低(P<0.05).2)吊尾加100 Hz正弦波振动7 d后,与单纯吊尾组相比肌梭的传入放电明显增多(P<0.05). 结论 100 Hz正弦波振动可选择性兴奋肌梭,使悬吊大鼠比目鱼肌肌梭的传入放电明显增多.     

Antagonist muscle activity during stretching: a paradox re-assessed

The purpose of this investigation was to examine and compare the simultaneous electromyographic activity from surface and implanted wire electrodes of an antagonist pair of muscles during a reversal stretching technique. Previous studies reported increased electromyographic activity of a muscle being stretched during antagonist muscle activation. Five male subjects performed a stretching method which consisted of active plantarflexion, followed by active dorsiflexion. Adjacent surface and implanted wire electrodes were applied to the soleus and tibialis anterior muscles. Comparison of the surface electrode recordings showed apparent cocontraction during dorsiflexion. However, no activity was observed on the soleus wire electrode trace during the dorsiflexion phase of the stretching method. Power spectral analysis showed a significant (P less than 0.001) frequency shift between plantarflexion (91.9 V2.Hz-1) and dorsiflexion (66.1 V2.Hz-1) from the surface electrode recordings. Cross-correlation between tibialis anterior and surface soleus activity during dorsiflexion provided strong evidence that the apparent electromyographic soleus signal originated in the tibialis anterior muscle with an average of 8.7 ms delay of the surface soleus signal. Although not generalizable to other studies, it was concluded that in this study the tracings from the surface electrodes, which gave the appearance of co-contraction between antagonist muscles, were actually cross-talk between the electrodes. The rationale for antagonist contraction during stretching in order to inhibit contraction of the muscle being stretched is supported with this evidence and is consistent with those studies which show greater range of motion gains using the reversal technique.     

The soleus muscle acts as an agonist for the anterior cruciate ligament. An in vitro experimental study

BACKGROUND: Although the quadriceps muscles are known antagonists for the anterior cruciate ligament and the hamstring muscles are known agonists, the influence of the calf muscles on knee stability is not well understood. HYPOTHESIS: The soleus muscle acts as an anterior cruciate ligament agonist and the gastrocnemius muscle acts as an anterior cruciate ligament antagonist. STUDY DESIGN: Controlled laboratory study. METHODS: Six cadaveric knees were tested with individual and combined activation of the gastrocnemius and soleus muscles to determine the influence of simulated muscle contraction on tibiofemoral motion. RESULTS: At all flexion angles, applying the soleus muscle force tended to translate the tibia posteriorly, whereas applying the gastrocnemius muscle force tended to translate the tibia anteriorly. Applying the soleus and gastrocnemius muscle forces together also tended to translate the tibia anteriorly. The average anterior and posterior tibial translations were greatest at 50 degrees of flexion. CONCLUSIONS: The soleus muscle is capable of acting as an agonist for the anterior cruciate ligament and the gastrocnemius muscle can act as an antagonist. CLINICAL RELEVANCE: A better understanding of the agonistic behavior of the soleus muscle on the anterior cruciate ligament may lead to the development of training and rehabilitation strategies that could reduce the incidence of injury and improve function in both patients with anterior cruciate ligament deficiency and patients who have undergone anterior cruciate ligament reconstruction.