| Summary: | 碩士 === 朝陽科技大學 === 工業工程與管理系碩士班 === 98 === For industrial tasks involving manual operations, the workers need to generate sutiable grip strength to hold the object or to safely and effectively control and use the hand tools. Previous studies related to grip strength focused on exploring the maximum and submaximum grip strength or maximum enduration time for gripping exertions for bare and gloved hands. However, no literatures were found investigating suitable duration for sampling of consecutive maximum grip strength without fatigue and at the same time acceptable by the subjects.
This study use grip dynamometer and electromyography (EMG) module to collect EMG signals for four forearm muscles when performing consecutive maximum gripping exertions for bare and gloved hands using two or four minutes rest period between gripping efforts. Ten males and eight females participated in this experiment. The suitable sampling duration will be the time that 90% of males and 75% of females can perform consecutive MVC gripping exertions without fatigue. Borg 10-point scale was also used to measure the discomfort level during the consecutive maximum gripping exertions.
The results show that there were statistically significant differences in maximum grip strength between gloving condition, rest time, and gender. Muscle activities in extensor carpi radialis longus (ECR), extensor digitorum (ED) were also differed significantly between two and four minutes rest period. Based on Joint analysis of EMG spectrum and amplitude (JASA), the subjects can follow the recovery time of 2 minutes of Caldwell’s regimen between consecutive grip exertions for all four gripping conditions without fatigue. However, the average grip strength during the sampling period for 4 minutes rests test are 2.6 ± 0.6 Kg higher than the 2 minutes rest tests.
In this study, the suitable sampling duration is defined as the time that the subject can maintain 80% of the maximum grip strength during consecutive maxumum gripping exertions. For each of the four different gripping conditions (bare hand-2 minutes rest, gloved hand-2 minutes rest, bare hand-4 minutes rest, gloved hand-4 minutes rest), the results show that the suitable sampling duration that 90% of males and 75% of females can perform consecutive MVC gripping exertions without fatigue were 17、8、48、38 minutes and 47、32、98、58 minutes, respectively.
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