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Effectiveness of a handle flange for reducing manual effort during hand tool use.
Int J Ind Ergon 1993 Oct; 12(3):199-207
The effectiveness of adding a flange to handles on reducing grip force requirements when using hand tools was examined. The study group consisted of 30 right handed male volunteers, 18 to 30 years old, free of musculoskeletal problems. Half of the subjects grasped and lifted 2.5 by 1.3 by 14 centimeter rectangular aluminum bar handles with or without a flange located at the top of the handle (lifting task). The other 15 subjects grasped and pulled similar handles with or without a flange located on the bottom (pulling task). The handles in both experiments were instrumented with a strain gauge and connected to load cells. Each experiment was performed at three levels of weight (load cell resistance). Grip forces were recorded and expressed as a percentage of the maximum voluntary contractile (MVC) forces which were measured in a preliminary experiment. Electromyographic (EMG) activity recorded from the flexor pollicis longus, flexor digitorum superfacialis, and extensor digitorum muscles of the forearms was monitored. In each experiment, increased load cell resistance produced corresponding increases in force exertion. In the lifting task, average grip forces ranged from 6.6 to 19.2% of MVC and peak grip forces ranged from 12.4 to 32.7% of MVC. In the pulling task, average and peak grip forces varied from 5.1 to 11.6 and 12.6 to 21.6%, respectively. The presence of the flange did not significantly affect peak or average grip force in either experiment. The lifting task was associated with significantly higher levels of EMG activity than the pulling task. The presence of the flange did not significantly affect forearm muscle EMG activity. The authors conclude that placing a flange on the handle does not significantly reduce the grip force required to perform the examined lifting or pulling tasks.
Ergonomics; Hand-tools; Equipment-design; Manual-lifting; Task-performance; Simulation-methods; Muscle-contraction; Injury-prevention; Cumulative-trauma-disorders; Electrophysiological-measurements
Issue of Publication
International Journal of Industrial Ergonomics
Page last reviewed: April 12, 2019
Content source: National Institute for Occupational Safety and Health Education and Information Division