Farooq Mohd, Khan Abid Ali
Department of Mechanical Engineering, Aligarh Muslim University, Aligarh, UP, India.
Work. 2012;43(3):263-78. doi: 10.3233/WOR-2012-1391.
To investigate the effects of upper limb postures on discomfort score for repetitive gripping task.
Eighteen right handed male participants volunteered in the experimental investigations.
The present study was divided into two experiments. A Full factorial design of 2 (Two shoulder rotation angles) × 3 (Three elbow flexion angles) × 3 (Three upper arm rotation angles) was used. The effect of postures on MVC grip strength, Grip endurance and on discomfort score, for a repetitive task at 150 N ± 5 N with exertions 15 per minute was recorded. In a supplementary experiment, the EMG recordings were also taken for validating the effect of elbow flexion angle.
ANOVA showed that the main effects of postures were not significant on MVC grip, except elbow flexion (p < 0.001). The endurance time was also significant (p=0.0100) for elbow flexion and there was no effect of other postures. The second experiment showed that the effect of shoulder rotation, elbow flexion and forearm rotation was significant (p <0.001) on discomfort score. The EMG activity of the muscles also showed that FDP and ECRB muscles had maximum reduction in median frequencies of the EMG signals of the respective muscles at 45° elbow flexion angle.
The main effects of elbow flexion angle, shoulder rotation and forearm rotation were significant on discomfort score for the repetitive gripping task of the present study.
研究上肢姿势对重复性抓握任务不适评分的影响。
18名右利手男性参与者自愿参与实验研究。
本研究分为两个实验。采用2（两个肩部旋转角度）×3（三个肘部屈曲角度）×3（三个上臂旋转角度）的全因子设计。记录在150 N±5 N、每分钟15次用力的重复性任务中，姿势对最大自主收缩握力、握力耐力和不适评分的影响。在一个补充实验中，还进行了肌电图记录以验证肘部屈曲角度的影响。
方差分析表明，除肘部屈曲外（p<0.001），姿势对最大自主收缩握力的主要影响不显著。肘部屈曲的耐力时间也具有显著性（p = 0.0100），其他姿势无影响。第二个实验表明，肩部旋转、肘部屈曲和前臂旋转对不适评分有显著影响（p<0.001）。肌肉的肌电图活动还表明，在肘部屈曲角度为45°时，指深屈肌和桡侧腕短伸肌的肌电图信号中位频率下降最大。
在本研究的重复性抓握任务中，肘部屈曲角度、肩部旋转和前臂旋转对不适评分有显著的主要影响。
