| Summary: | 碩士 === 華梵大學 === 工業工程與經營資訊學系碩士班 === 94 === The purpose of this study is to evaluate the effect of handle angle design of materiel container on maximum voluntary isometric contaction (MVC), power grip, wrist deviation, electromyography (EMG), ratings of perceived exertion (RPE) and heart rate (HR). In this experiment, six Taiwanese subject (3 male and 3 female) were recruited to participate from Huafan University. A nested-split plot design was employed, in which the independent variables included gender, subject (nested within gender), handle angle (0°,15°,30°,45°,60°,75°and 90°), box width (30cm , 40 cm and 50 cm) and lifting height (knee and shoulder). Each subject needed to perform 42 experiment combination (7 handle angle × 3 box width × 2 lifting height). Dependent variables included MVC, left/right hand wrist deviation, left/right hand power grip, EMG, RPEs and HR. The results showed that deltoid and erector spine NEMG, left/right hand power grip, left/right wrist deviation were significantly affected by handle angle. Box width significantly influenced the erector spine NEMG. In addition, MVC, wrist and whole body RPE, flexor digitorum superficialis NEMG, flexor carpi radialis NEMG, biceps brachii NEMG, left/right hand power grip, wrist deviation were significantly affected by lifting height. The interaction of MVC and right hand radial deviation were significantly affected by handle angle and lifting height. The interaction of gender and lifting height had significant influeace on MVC, wrist RPE and whole body RPE, flexor digitorum superficialis NEMG, flexor carpi radialis NEMG, deltoid NEMG, left hand power grip, left/right hand wrist deviation (P<0.01). The interaction of left/right hand wrist deviation were significantly affected by gender and box width.
Furthermore, with the increase of the handle angle from 0˚ to 90˚, the left/right hand power grip increased gradually, but deltoid and erector spinae NEMG decreased. The handle angle increasing from 0˚ to 30˚ caused the wrist ulnar deviation decreasing; the handle angle increasing over 30˚ to 90˚ induced the wrist radial deviation increasing. For the wrist and whole body RPE, the greatest RPEs appeared at 90˚, the smallest RPEs at 30˚. For improving wrist posture and decreasing the needed power grip, the handle angle from 30˚ to 45˚ was recommended.
The MVC, flexor digitorum superficialis NEMG, flexor carpi radialis NEMG and whole body RPE at knee height were greater than that at shoulder height. On contrary, the lower left/right hand power grip, left/right wrist deviations, deltoid NEMG, appeared at knee height. In addition, the 40-cm container width induced the greatest erector spinae NEMG; the smallest appeared at 50 cm.
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