A study of upper limb muscle activity on light assembly task at two different work rates

Electronic industry is the leading industry in manufacturing sectors and one of the largest employers in Malaysia. A cross sectional survey in electronic (semi conductor) industry shows that assembly line workers had the highest prevalence of neck/shoulder and upper back pain. This study aims to elucidate the effect of cycle time reduction on upper limb muscle in a light assembly task using LEGO¿ construction block. Eight subjects (4 males and 4 females) were participated in this study. Electromyography (EMG) activity of brachiroadialis, biceps brachii, anterior deltoid and upper trapezius muscle was recorded for one hour experiment. Subjects used dominant hand to pick the pieces of LEGO¿ and assembled with the plate. The experiments were done twice (in separate day) in different work rate (20 movements/minute and 12 movements/minute). Root Mean Square (RMS) of EMG data was analyzed using SPSS v.15. Independent sample t test was used to know the significant effect of work rate to the muscle activity. The result shows that there is a significant effect of reduction cycle time on bracioradialis, biceps brachii, anterior deltoid and upper trapezius muscle in a light assembly task.