Psychophysical and EMG correlates of force exertion in manual work.
Grant KA; Habes DJ; Putz-Anderson V
Int J Ind Ergon 1994 Feb; 13(1):31-39
The use of electromyography (EMG) and psychophysical rating of perceived exertion (RPE) as predictors of grip force in dynamic tasks was examined and compared. The subjects were 45 males ages 18 to 30, who were all right handed and did not have any musculoskeletal impairments. Subjects performed two work tasks. The first was a material transfer task in which a 3.8 centimeter diameter cylindrical handle was grasped and moved from one side of a circular platform to another side. In this task, the mass and shape of the handle was altered. The second task was an assembly operation task, in which a cylindrical handle suspended from a rope was griped and pulled downward. In this experiment, the rope tension and handle shape were altered. Right forearm EMG were monitored using surface electrodes placed over the flexor pollicis longus, flexor digitorum superficialis, and extensor digitorum muscles using a Therapeutics Unlimited model 544 EMG system. Grip force was measured using a strain gage mounted in the handle. The Borg CR/10 rating scale was used to access perceived exertion. The results indicated that in all experiments, EMG and RPE correlated strongly and positively with grip force. Neither EMG or RPE alone was a consistently better predictor of grip force. The authors conclude that psychophysical rating methods such as the RPE may be suitable alternatives to EMG measurements for estimating force in manual work because of its simplicity and convenience.
Electrophysiological-measurements; Work-analysis; Psychological-testing; Men; Manual-materials-handling; Muscle-physiology; Task-performance
International Journal of Industrial Ergonomics