梯度负重伸展状态下竖脊肌形态与功能的变化特征

Morphological and Functional Characteristics of Erector Spinae Muscle under Different Degrees of Resistance Contraction

目的研究竖脊肌在对抗不同负荷抗阻收缩时的形态和功能变化特征,探究科学评估竖脊肌状态的敏感指标。方法 20名男性大学生作为受试者参加实验。受试者俯卧于罗马椅腰腹测试仪,测试腰背肌最大随意收缩(MVC)时负重量,采用彩色超声影像仪和表面肌电仪首先采集静止无负重、MVC负重时受试者左、右竖脊肌厚度、横截面积和表面肌电信号,随后依次进行20%MVC、40%MVC、60%MVC、80%MVC负重时的竖脊肌超声、肌电测试,每个测试间隔5 min。结果左右竖脊肌在负重时积分肌电(IEMG)、肌肉厚度均与放松时具有显著性差异(P<0.05),且IEMG在放松~20%MVC和80%~100%MVC之间增值最大,肌肉厚度在放松~20%MVC和60%~80%MVC之间出现最大增值;横截面积在80%和100%MVC时与放松状态下具有显著性差异(P<0.05)。肌电与肌肉用力程度呈现显著相关性,左侧r=0.82(P<0.05),右侧r=0.85(P<0.05)。肌肉用力程度与厚度的相关性大于与横截面积的相关性,厚度与面积呈现较高相关性且在放松状态、60%MVC、80%MVC状态时二者相关性明显高于20%MVC、40%MVC状态。结论相较于竖脊肌形态指标,肌电指标对肌肉用力的敏感性更高;相较于横截面积,厚度指标更能精确反映肌肉的用力程度。最大用力状态下竖脊肌肌纤维募集程度较次最大用力时增加显著。

Objective To study the morphological and functional changes of erector spinae muscle in response to different loads and contractions,and to explore the sensitive indexes for scientific evaluation of erector spinae muscle state.Methods Twenty male college students were recruited to participate in this experiment.The subjects were asked to lie flat on a Roman chair.The weight of the load on the back muscle was tested when the erector spine muscle was in the maximum voluntary contraction(MVC).Color ultrasonic imaging instrument and surface electromyography(EMG) instrument were used to collect the ultrasound signals(thickness and cross-sectional area) and surface EMG signals of subjects’ left and right erector spinae muscle at rest without weight load and then at 20% MVC,40%MVC,60%MVC and 80%MVC in turn,with an interval of 5 minutes for each test.Results IEMG and thickness of left and right erector spinae muscles were different from those in relaxation(P <0.05).IEMG increased the most between relaxation and 20% MVC,and 80% ~100% MVC,and muscle thickness increased the most between relaxation and 20 %MVC,and 60%~80% MVC.The cross-sectional area of the muscles at 80% and 100%MVC was significantly different from the relaxed state respectively(P<0.05).There was a very high correlation between electromyography and muscle strength,left,r=0.816(P<0.05),right,r=0.849(P<0.05).The correlation between muscle strength and thickness was greater than that between thickness and cross-sectional area.The thickness and area were highly correlated,and the correlation between them at 60 % MVC state and 80%MVC state were significantly higher than that in the 20 % MVC and 40 % MVC state.Conclusion The electromyographic index of erector spinae muscle could reflect the different degree of muscle exertion more accurately than the morphological index.Muscle thickness was a more sensitive indicator of muscle strain than cross-sectional area.In the maximal force state,the degree of muscle fiber recruitment of the erector spinae muscle increased significantly compared with that of the submaximal force.