Effect of upper limb postures on discomfort by repetitive isometric gripping

The objective of this study was to investigate the effect of upper limb postures on discomfort by repetitive gripping tasks. In the present experiment, the three levels of the upperarm abduction angle (0 degrees, 45 degrees, and 90 degrees) with three levels of the elbow flexion angle (45 degrees, 90 degrees, and 135 degrees) were taken as independent variables to find the effect on discomfort by repetitive gripping (150N+5N) at 15 exertions per minute. Eighteen (participants) x three (upper arm abduction angles) x three (elbow flexion angles) custom design of the experiment was used for the analysis of variances (ANOVA). The perceived discomfort score on 10 degrees mm visual analogue scale was recorded as a dependent variable. The results showed that there was significant effect of elbow flexion angle on discomfort for repetitive gripping task (p<0.001). However there was not significant difference in discomfort for the similar task for 90 degrees compared with 1350 flexion of elbow joint (p>0.05). The EMG recording of FCR muscle showed that the reduction in the mean Median Frequency was more for 450 elbow flexion angle, but the comparatively less difference was noticed for the 900 and 1350 elbow flexion angles. In conclusion, elbow flexion angle has a significant effect on discomfort by repetitive gripping tasks.