Working height and parts bin position effects on upper limb muscular strain for repetitive hand transfer

• Muscular load reduction on upper limbs for repetitive handling is a major issue in industries.
• Awkward postures and high repetitiveness were major factors affecting upper limb muscle fatigue.
• Working height should be organized at or below elbow height for upper limb repetitive tasks.

The study examines the influence of workplace layout on localized muscle fatigue in a simulated repetitive seated hand transfer task. Nine task conditions were used consisting of three working heights and three parts bin positions. Six muscles in the right upper limb were monitored bilaterally using surface electromyography. Motion range data on the upper segmental joints were collected along with subjective perception data. Results showed that awkward postures due to workstation setting and high repetitiveness were the major factors affecting upper limb muscle fatigue, especially for the trapezius and anterior deltoid. The percentage of fatigued subjects generally increased when the mean working height became greater. This study suggests that working height should be organized at or below the elbow level with the parts bin position not above the working height when a repetitive hand transfer task is performed.Relevance to industryThis experimental result should be useful in job analysis for the evaluation of muscle activities and workplace layout design for the reduction of muscular load on the upper limbs during repetitive handling of light weight in industries characterized as hand transfer.