Zhao Peng-fei, Ma Qiang, Chen Xue-wei, Zhang Kuan, Ai Ting-ting, Man Ze-ming
Institute of Health and Environmental Medicine, Academy of Military Medical Science, Tianjin, China.
Zhonghua Lao Dong Wei Sheng Zhi Ye Bing Za Zhi. 2012 Jul;30(7):501-3.
To analyze and evaluate the fatigue of shoulder skeletal muscle caused by different lifting loads with surface electromyography (sEMG).
According to the loading standard of1 Repetition Maximum (1RM), ten male volunteers performed 3 tasks of upper limb flexion, i.e. 10%, 50% and 90%-1RM. During action process, the signals of Upper Trapezius (UT), Lower Trapezius (LT), Serratus Anterior (SA) and Anterior Deltoid (AD) were recorded by sEMG. The Mean Amplitude (MA) served as an index to evaluate the changes in skeletal muscle fatigue.
The scores of Borg were 15.6, 15.9 and 15.2 for 3 loads of 10%-1RM, 50%-1RM and 90%-1RM, respectively (P > 0.05). The mean amplitudes (MAs) of Upper Trapezius, Lower Trapezius, Anterior Deltoid and Serratus Anterior in shoulders increased obviously. Under the load intensity of 10%-1RM, the MAs of Upper Trapezius and Anterior Deltoid increased significantly (P < 0.05), which were 0.898 and 0.736, respectively. After the exhaustion, the contribution of mean amplitude in shoulder muscle did not change significantly (P > 0.05).
The low-load action for long time can induce easily the fatigue of upper trapezius and anterior deltoid.
采用表面肌电图（sEMG）分析和评估不同举重负荷引起的肩部骨骼肌疲劳。
根据1次重复最大负荷（1RM）的负荷标准，10名男性志愿者进行3项上肢屈曲任务，即10%、50%和90%-1RM。在动作过程中，通过sEMG记录斜方肌上束（UT）、斜方肌下束（LT）、前锯肌（SA）和三角肌前束（AD）的信号。平均振幅（MA）作为评估骨骼肌疲劳变化的指标。
10%-1RM、50%-1RM和90%-1RM这3种负荷下的Borg评分分别为15.6、15.9和15.2（P>0.05）。肩部斜方肌上束、斜方肌下束、三角肌前束和前锯肌的平均振幅（MAs）明显增加。在10%-1RM的负荷强度下，斜方肌上束和三角肌前束的MAs显著增加（P<0.05），分别为0.898和0.736。力竭后，肩部肌肉平均振幅的贡献率无明显变化（P>0.05）。
长时间低负荷动作容易诱发斜方肌上束和三角肌前束的疲劳。
