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目的用表面肌电描记术(surface electromyography,SEMG)评价低力量负荷下,频率、重量和运动角度3个负荷因素对重复性伸腕运动中前臂肌肉应激状态和疲劳的影响。方法16名男性志愿者在规定的重量(1．96、4．90 N)、频率(8．0、33．3次/min)和角度(45°、90°)下做8组伸腕动作各20 min,并在作业开始和结束后做20%最大随意收缩力(MVC)的静态伸腕动作2～3s,采集并分析其尺侧腕伸肌和指伸肌的表面肌电信号。结果伸腕力量负荷(1．96、4．90 N)分别约为伸肌MVC手收缩力的1．40%和3．50%。当3个负荷因素的水平升高时,肌电的平均功率频率(MPF)和中位频率(MF)均降低,其中指伸肌MPF降低的差异有统计学意义(P＜0．05或P＜0．01),其MF在角度和重量两因素中的改变差异有统计学意义(P＜0．05或P＜0．01)。随负荷水平的升高,伸肌波幅值可分3～4组,组间差异有统计学意义(P＜0．05)；逐步回归分析显示,3因素负荷水平均与肌电波幅值呈正相关．结论各作业中指伸肌均明显疲劳；伸肌疲劳的首要负荷因素是频率,其次是重量和角度；MF、MPF和波幅指标可以描述低力量负荷下前臂肌肉的应激和疲劳状况。
OBJECTIVE: To evaluate the effect of stress, fatigue and weight loss on forearm muscle during repetitive extensor arm movements by surface electromyography (SEMG). Methods Sixteen male volunteers performed 8 sets of wrist exercises under the prescribed weight (1.96,4.90 N), frequency (8.0,33.3 beats / min) and angle (45 °, 90 °) Each 20 min, and at the beginning and end of the operation to do 20% of the maximum voluntary contraction force (MVC) static wrist movements 2 ~ 3s, collecting and analyzing the ulnar wrist extensor and facial extensor surface EMG signals. Results The results of wrist force load (1.96,4.90 N) were about 1.40% and 3.50% of extensor MVC hand contractility respectively. The mean power frequency (MPF) and median frequency (MF) of myoelectricity decreased when the level of 3 stress factors increased. The difference of MPF between extensor and extensor muscle was statistically significant (P <0.05 or P <0.01). There was significant difference in the change of MF between angle and weight (P <0.05 or P <0.01). With the increase of the load level, the extensor muscle amplitude can be divided into 3 to 4 groups, the difference between the groups was statistically significant (P <0.05); stepwise regression analysis showed that the 3-factor load level and myoelectric amplitude was positive Related. CONCLUSION: The extensor muscles of middle finger were obviously fatigue. The main load factors of extensor fatigue were frequency, followed by weight and angle. The MF, MPF and amplitude indicators could describe the stress and fatigue of forearm muscles under low power load.