重复性作业前臂肌肉疲劳及危险因素的表面肌电分析

Experimental Study on Forearm Muscles Fatigue and Risk Factors in Repetitive Work with Surface Electromyography

目的用表面肌电(surface electromyogram,SEMG)频域分析指标中位频率(median frequency,MF)和平均功率频率(mean power frequency,MPF)评价和预测重复性作业中前臂伸肌及其拮抗肌的负荷和危险因素。方法16名男性受试者按照规定的频率(8次/min和33.3次/min)、重量(1.96N和4.9N)和角度(45°和90°)负荷各做8组伸腕作业,各组作业结束后,均立即做20%最大随意收缩(maximum voluntarycontraction,MVC)的静态收缩,测定并分析其SEMG。结果指伸肌(extensor digitorium,ED)、桡侧腕屈肌(flexor carpi radialis,FCR)和尺侧腕屈肌(flexor carpi ulnaris,FCU)的MPF和MF在频率负荷高剂量组较低剂量组降低,组间比较,差异有显者性(P<0.05,P<0.01);ED的MPF和MF在频率、角度和重量负荷高剂量组均较低剂量组低,组间比较,差异有显著性(P<0.05,P<0.01);角度是主动肌尺侧腕伸肌(extensor carpi ulnaris,ECU)、ED和拮抗肌FCR疲劳的首位危险因素。结论各肌肉疲劳程度不同,ED最明显,ECU疲劳最轻,拮抗肌同样出现疲劳;伸腕的角度是主动肌(伸肌)疲劳的首位危险因素,也是拮抗肌(屈肌)疲劳的首位影响因素。

Objective Using the frequency domain indexes of surface electromyography （SEMG） such as mean power frequency （MPF） and median frequency （MF） to evaluate and predict the work load and their risk factors of the forearm agonistic and antagonistic muscles in repetitive work. Methods 16 male volunteers performed 8 wrist extending tasks respectively under determined frequency （8 times/min, 33.3 times/min）, weight （1.96N, 4.9N） and angle （45°, 90°） loads. Static contractions were performed after each task at level of 20% maximum voluntary contraction （MVC） immediately, and the SEMG signal was recorded and analyzed. Results The MPF and MF of extensor digitorium （ED）, flexor carpi radialis （FCR） and flexor carpi ulnaris （FCU） were lower at higher dose levels of frequency, the difference were significant （P〈0. 01, P〈0.05）. MPF and MF of ED were lower at higher dose levels of frequency, angle and weight, the difference was significant（P〈0.05,P〈0.01）. Angle was the first risk factor of fatigue of extensor carpi ulnaris （ECU）, ED and FCR. Conclusions The fatigue degrees of muscles were different, the highest in ED and the lowest in ECU. And the antagonistic muscle also fatigued in this experiment, angle is the first risk factor of fatigue of forearm agonistic extensor muscle and antagonistic flexor muscle.