| Summary: | 碩士 === 朝陽科技大學 === 工業工程與管理系碩士班 === 101 === Four main ergonomics factors to affect the upper limb musculoskeletal
disorders are: awkward postures, overexertion, repetition and work/rest.
However, few literatures have been emphasized on the work and rest time
arrangement for upper limb repetitive tasks.
An experiment was conducted to collect electromyographic data (EMG),
force and heart rate when a simulated repetitive task was performed in the
laboratory. Twelve young male subjects were recruited. Eight experimental
factors were included：4 different rest time periods (0.25, 0.5, 1, and 1.5 times of
work time of 9 min) and 2 different object loads (1 and 2 kg), in this study. The
Viewlog software developed was used to calculate %MVC (maximum voluntary
contraction, MVC) from electromyographic signals of tested muscles to explore
the upper limb muscle fatigue recovery.
The EMG results showed that the rest time period change might
significantly affect the tested muscles. The EMG results, on rest time period of
0.25 times work time, obtained from biceps brachii, middle deltoid, and anterior
deltoid, had the significantly different muscle fatigue recovery (p＜0.05) when
compared with the other three rest time periods (the recovery more than 90%).
The EMG results measured from triceps brachii on the rest time period of 1.5
times work time showed significantly different (p＜0.05) when compared with
the other rest time periods. It was recommended rest time should be taken at 0.5
times of the working time, and the recovery might reach between 87.3% and
98.6%.
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