An electromyographic study of maximum torques and upper extremity muscle activity in simulated screwdriving tasks

Autor: Katharyn A. Grant, Daniel J. Habes
Rok vydání: 1997
Předmět:
Zdroj: International Journal of Industrial Ergonomics. 20:339-346
ISSN: 0169-8141
DOI: 10.1016/s0169-8141(96)00069-8
Popis: The effects of workstation and tool handle design on strength and upper extremity muscle activity during a simulated manual screwdriving task were examined. Fifteen male participants performed maximal (100%) and submaximal (75% and 50%) exertions with a screwdriver using postures frequently observed in industry. Investigators varied handle height, reach distance, handle diameter, and handle orientation during the experiment. The activity of the anterior deltoid, triceps brachii, biceps, extensor digitorum, flexor digitorum superficialis and flexor pollicis longus was monitored using surface electromyography (EMG). The ratio of normalized EMG activity to torque produced during the exertion was computed for each muscle under each condition. The results indicated that increased torque capability was associated with the use of a larger (3.7 cm), vertically oriented handle. EMG/torque ratio generally increased as handle height was increased, reach distance and handle diameter were reduced, and the handle orientation was changed from vertical to horizontal. This study supports the premise that workstations and tools can be configured to maximize worker capabilities while minimizing the potential for muscle strain and fatigue. These data may be useful to job analysts for assessing the relative demands of construction and assembly work. Relevance to industry These data can be used by job analysts to grade the level of muscle activity required by screwdriving tasks (relative to similar exertions in different postures), and to justify workstation changes to reduce muscular stress on the upper extremities.
Databáze: OpenAIRE
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