• Journal of the Ergonomics Society of Korea
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• v.24 no.2
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• pp.65-70
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• 2005

Evaluation of repetitiveness for upper extremity intensive tasks is essential to determine the level of risk for upper extremity musculoskeletal disorders at the workplace. However, experimental data available to establish the acceptable levels of repetitiveness for various postures and forces is lacking. The present study examined the maximum acceptable frequencies(MAFs; motions/min.) of shoulder, elbow, wrist, and index finger motions at different forces(1kgf and 4kgf for shoulder, elbow, and wrist; 0.25kgf and 1 kgf for index finger) in sitting. Seventeen right-handed males in 20s without having any history musculoskeletal disorders participated in the MAF experiment. The participants determined their MAFs for the upper extremity motions by using the self-adjustment method and their work pulse(increase in heart rate; beats/min.) and rating of perceived exertion(RPE) were measured when working at MAF. The MAFs of elbow, wrist, and index finger motions for each force level were about 2, 3, and 6 times the corresponding MAF(9 at the high force and 24 at the low force) of shoulder motion and the MAFs at the low force increased about 2 times those at the high force. The work pulses of elbow, wrist, and index finger motions for each force level were 70%, 50%, and 30% of the corresponding work pulse(17 at the high force and 12 at the low force) of shoulder motion and the work pulses at the low force were about 70 % of those at the high force. Lastly, the RPEs of the upper extremity regions were about level 3(moderate) or below.

• Proceedings of the ESK Conference
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• 1994.04a
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• pp.41-48
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• 1994

A laboratory experiment was conducted to examine the effect of varying working conditions on drilling frequendcy for females. Results of ANOVA showed that angle of wrist flexion and force had significant effects on drilling frequency. As angle ofwrist flexion and force increased drilling frequency decreased significantly. A set of 4 regression models were developed to predict maximum acceptable frequency (MAF) for drilling as a function of wrist flexion angle, force, and various physiological measures with could be applied in industrial situations